Frequently Asked Questions 

Frequently asked questions on refrigerant “FREON”

Frequently asked questions on heat pumps

Frequently asked questions about humidity

Frequently asked questions on filtration

Frequently asked questions on air purifiers

General frequently asked questions

Frequently asked questions on Indoor Air Quality

Frequently asked questions on UV-C

Frequently asked questions on ductwork

Frequently asked questions on performance

Frequently asked questions on refrigerant “FREON”

What Is The Difference Between R-22 And R-410A Refrigerants?

Refrigerants are what make air conditioning possible. Contained within the coils of an air conditioner, these liquid agents cool and dehumidify indoor air. For years, the most common refrigerant used in air-conditioning systems was R-22.

In response to growing environmental concerns, production of systems using R-22 refrigerant is being phased out. Systems are now being manufactured with chlorine-free R-410A refrigerant. Because R-410A contains no chlorine, it is considered ozone friendly.

Why is “Freon” being phased out?

“Freon” is a trademark name that has been used to refer to several different refrigerants, including chlorofluorocarbons (CFCs) such as R-12, and hydro chlorofluorocarbons (HCFCs) such as R-22, Under the U.S. Clean Air Act and the Montreal Protocol on Substances that Deplete the Ozone Layer, the United States phased out CFCs in the 1990s, and is currently phasing out HCFCs.

These chemicals eventually reach the stratosphere where they deplete the stratospheric ozone layer. The ozone layer helps protect us from harmful ultraviolet (UV) radiation that can cause skin cancer and cataracts. Phasing out ozone-depleting substances globally under the Montreal Protocol is expected to avoid more than 280 million cases of skin cancer, approximately 1.6 million skin cancer deaths, and more than 45 million cases of cataracts in the United States among individuals born between 1890 and 2100.  Increased UV radiation caused by depletion of the ozone layer also harms plants, crops, marine ecosystems and various materials like plastics and paint. Get more information on the health and environmental effects of ozone layer depletion.

What does this mean for people with air conditioners that use R-22?

People can continue to use air-conditioning (AC) equipment that uses R-22, whether it is a window unit or a central cooling system. EPA does not require homeowners to replace their existing equipment. As of January 1, 2020, no new R-22 will be made or imported into the United States, but used R-22 that is cleaned up to the same specifications as new refrigerant will continue to be available.

The most important thing an equipment owner can do is to maintain their AC unit properly, because appropriate servicing minimizes potential environmental damage and prolongs the life of the system. When selecting a technician, make sure he/she has the required EPA Section 608 certification needed to service equipment containing R-22. Homeowners should also request that service technicians locate and repair leaks instead of “topping off” leaking systems to protect the environment, minimize future service calls and repair costs, and reduce equipment operation costs by improving performance. It is also illegal to intentionally release any refrigerant when maintaining, servicing, repairing or disposing of AC equipment

Will retrofitting my system effect my energy use?

Air conditioning equipment generally runs most efficiently on the type of refrigerant it was designed for, but when the time does come to replace or retrofit your system, there are many non-ozone-depleting alternatives available. There is no EPA requirement to convert existing R-22 units for use with a non-ozone-depleting substitute refrigerant. Such conversions, called “retrofits,” are allowed if the alternative has been found acceptable under EPA’s Significant New Alternatives Policy (SNAP) program for that type of use. There are no “drop in” replacements for R-22. Alternative refrigerants will not work well without making changes to system components. As a result, service technicians who repair leaks to the system will most often continue to charge R-22 into the system as part of that repair. If a homeowner chooses to have their appliance retrofitted to another type of refrigerant it is important to ensure a technician with Section 608 certification recovers any remaining R-22 in the system before adding the non-ozone depleting alternative and explains how the conversion to a different refrigerant might affect the system’s performance and energy use.

How can I find out what kind of refrigerant my home air conditioner contains?

The refrigerant used in your home air conditioner is typically listed on the unit’s nameplate. For central air conditioners, the nameplate is usually on the outdoor condenser. If there is no nameplate, check your owner’s manual or contact the person or company that sold or services your air conditioner. If you know the manufacturer and model number, you could also call the manufacturer or check its website.

Can I still purchase a home air conditioner that contains R-22?

You can no longer purchase a central AC unit that uses R-22. However, you can continue to service your existing R-22 system. You can also purchase a “self-contained” system (typically, a window unit) if it is second-hand and/or was produced prior to 2010. 

Will there be enough R-22 available to continue to service my system?

R-22 that is recovered and reclaimed, along with R-22 produced prior to 2020, will help meet the needs of owners of existing R-22 systems well beyond the phaseout date. Continuing to service a unit with R-22 may not always be the most practical due to increase in price and availability. This is going to vary greatly on your area.

Are refrigerants available for home air conditioners that do not harm the ozone layer?

Yes, a number of ozone-friendly refrigerants are available and widely used today. The most common alternative in new AC systems is R-410A. While R-410A is a blend of two hydrofluorocarbons. Like the ozone depleting refrigerants being replaced, most HFCs are potent greenhouse gases and also must be handled consistent with EPA’s Refrigerant Management Program requirements. EPA maintains a full list of acceptable substitutes for residential and light commercial AC.

Is R-22a or 22a refrigerant the same as R-22?

No. R-22a or 22a refrigerant has been falsely marketed as R-22 or an R-22 replacement, but it is a hydrocarbon refrigerant blend whose primary components include flammable substances such as propane and butane. In some cases, it may also contain small amounts of other hydrocarbons or a pine-scented odorant.

This refrigerant is highly flammable and not an acceptable alternative for your residential AC system. Because R-22a is flammable and an R-22 AC system does not have safety features to address flammability, it can burn or explode if there is enough product concentrated in one space and the refrigerant comes in contact with an ignition source.

“R-22a” has been sold under the names Blue Sky 22a, Coolant Express 22a, DURACOOL-22a, EC-22, Ecofreeze EF-22a, Enviro-safe 22a, ES-22a, Frost 22a, Maxi-Fridge, MX-22a, Oz-Chill 22a, Priority Cool, and RED TEK 22a.

Can I replace the condensing unit (i.e., outdoor unit) on a home air conditioner that contains R-22?

It depends.  EPA regulations allow owners of existing R-22 home air conditioners to replace their condensing unit with a new one if it breaks or is damaged. However, the R-22 condensing units must meet regional efficiency standards when tested in accordance with DOE’s test procedure.

I own a home air conditioner that contains R-22. How can I minimize its impacts on the ozone layer and the climate system?

The most important step you can take is to maintain your unit properly. Major leaks rarely develop in properly installed and regularly maintained units. If your air conditioner leaks, ask your service technicians to locate and repair the leak instead of “topping it off.” Repairing leaks will keep your system operating at its best, while reducing refrigerant emissions and energy use. You can also save money by avoiding additional repairs in the future.

How should I select an appropriate technician?

Work with reputable dealers that employ service technicians who are EPA-certified to handle refrigerants used in air conditioners. Technicians often call this certification “Section 608 certification,” which refers to a portion of the Clean Air Act. When speaking with an AC service company, ask if their technicians are Section 608-certified. You can also ask a service technician to show you his/her certification card. If your air conditioner contains alternative refrigerants, the service technician should be trained in their use. Under Section 608 of the Clean Air Act, EPA prohibits individuals from knowingly venting refrigerants containing ozone-depleting refrigerants (including R-22) as well as their substitutes (such as HFCs, including R-410A), while maintaining, servicing, repairing, or disposing of AC and refrigeration equipment. Report a potential violation here.

What are questions homeowners should be asking their heating, ventilation, and air-conditioning (HVAC) contractor?

If your HVAC equipment is more than 10 years old or not keeping your house comfortable, EPA recommends that you have it evaluated by a professional HVAC contractor. If it is not performing efficiently or needs upgrading, consider replacing it with a system that has earned the ENERGY STAR label to save energy, save money and help protect the environment.

May I purchase my own refrigerant to recharge my appliance?

Section 608 Certification is required to recharge appliances. Refrigerant for stationary appliances is only sold to certified technicians or the companies that employ them.

How should I dispose of appliances containing refrigerants?

You have a number of options. If you purchase a new appliance, such as a refrigerator or freezer, the retailer will likely offer to remove the old one. Many governments and private organizations also can arrange for curbside pickup of appliances. Do not tamper with an appliance before it is disposed of, such as cutting refrigerant lines or removing compressors. The Clean Air Act prohibits the knowing release of most types of refrigerant during appliance disposal. Partners in EPA’s RAD program commit to collecting used refrigerated appliances and implementing best practices for the recycling/disposal of these units that go beyond federal laws. RAD Partners recover appliance foam, ensure compliance with laws on the recovery of refrigerant, used oil, mercury, and polychlorinated biphenyls (PCBs), and promote recycling of durable goods and the permanent retirement of old, inefficient appliances to save energy.

Frequently asked questions on heat pumps

What is Emergency Heat?

The Emergency Heat switch on a Heat Pump thermostat confuses many people. The fact of the matter is that most people don’t seem to understand exactly what Emergency Heat is and when they need to use it. Many people think that Heat Pumps don’t work in cold weather and they are supposed to use the Emergency Heat whenever it gets really cold, that is NOT the case.
Simply put, all Heat Pumps in northern climates (below 35 degrees) need a supplemental heating source. Usually it is in the form of electric resistance heating – at the indoor unit. This is an all-electric Heat Pump, but it could also be a gas, oil, or hot-water back-up system as well. The supplemental heat is also referred to as second-stage or back-up heating, with first-stage being the Heat Pump only. Emergency Heat is when you use your supplemental heat (2nd stage) by itself, without the use of your heat pump (1st stage heat).

Different systems and thermostats have different ways of determining when the second-stage heat comes on to assist the heat pump, but it is always done automatically. The two stages will work together in the colder months, and it is not necessary to switch your thermostat to Emergency Heat. So now we know that Emergency Heat is basically when you use your supplemental heat by itself.

When should I use Emergency Heat?

As the name implies, it is only used in emergency situations. It is used when there is something wrong with first-stage heating (the Heat Pump itself). In other words, if you notice your house is cold and it isn’t heating properly and you went outside and noticed that a tree fell and crushed your heat pump, that would be a good time to switch to Emergency Heat. 

Or if you look at the picture below; this Heat Pump turned into a block of ice due to a malfunction. At this point, it isn’t capable of providing any heat. Simply turn the thermostat to Emergency Heat and call for service.

What does Emergency Heat do?
When switching to Emergency Heat, the red indicator light will go on. And it will stay on until you stop using the Emergency Heat. This just lets you know you are in emergency mode. On a call for heat, no signal will be sent to the outdoor Heat Pump. Only the indoor unit and the back-up heat will run. On all-electric systems, this will provide enough heat to keep you going until the Heat Pump can be fixed. Gas/Oil/Hot-water system should provide plenty of heat.
Is Emergency Heat more expensive to run?

If you have an all-electric heat pump, then the answer is a definite YES! It is much more expensive to run your heat pump on Emergency Heat. And as the name implies, should only be run in an emergency until your heat pump can be repaired. Now if you have Gas or Oil heat for your backup system, then the answer isn’t so clear. It depends on the cost of your fuel, the efficiency of your heating system, compared to your electric rate and so on. But it is safe to say that the price increase won’t be as much as an all-electric system.

Why is the Emergency Heat light on?

As explained earlier, the Emergency Heat light will be on whenever your thermostat is set to Emergency Heat. But if your thermostat is not set to emergency heat and the light is on, then that usually indicates a problem with your heat pump. For more on this issue, see: Thermostat red light flashing or stays on.

Frequently asked questions about humidity

I’m noticing humidity or condensation issues in my home. What should I do?
The ideal relative humidity in a home should be between 30 to 50 percent. Humidity levels that are above or below that threaten to cause mold or other health issues. There are options, such as a modulating system or humidifier, to help monitor and regulate in-home humidity.
How often should I change my humidifier filter?
You should replace your humidifier filter at least once a year. Excess build-up of minerals, dirt, and pollutants can cause wear and damage to your humidifier, as well as making it operate less efficiently.
When should I turn my humidifier off and on?
Turn your humidifier on in the fall and turn it off in the spring.
What is the proper indoor humidity level?
Well, the optimum indoor range is around 35% relative humidity, but 30% to 40% tends to work best for many homes. If you go above this level, condensation on the windows can occur, breeding mold that leads to allergy and respiratory problems.
Is too much humidity a bad thing?
Dust mites, the leading cause of allergies, thrive in as little as 50% relative humidity. Allergens like molds thrive in relative humidity conditions above 60%, leading to a variety of aliments including asthma, allergies and respiratory infections.
Is too little humidity a bad thing?
Too little humidity on the other hand, can lead to dry nose and throat, dry skin, and static electricity, which can also ruin electronic devices such as computers, VCR’s, and DVD players. 

Maintaining proper and consistent humidity is also important for the wood inside your home; flooring, doors, and even pianos can shrink, crack, and warp if not properly humidified.
Why do I need a humidifier?
Energy savings is another benefit of keeping the proper humidity level. You will actually feel warmer and more comfortable in humidified air, so you can turn your thermostat down about 2 degrees (saving money), and still feel just as warm. Seriously, it works!

Frequently asked questions on filtration

How often should I check my air filter?

We suggest checking filters monthly. If you have a disposable type filter, (these usually have a cardboard edge), and if it is dirty, just replace it. Don’t attempt to clean it. Some higher efficiency pleated air filters can go up to three months before needing replacement. But in the higher-use seasons, it’s better to check more often.

Where is my HVAC system air filter located?

Different systems have different filter locations. If you don’t know where your filter is located, now would be a good time to learn! Usually, there is a removable filter access door in the return air duct next to the furnace or indoor unit. This can be in a basement, crawl-space, utility closet, garage, or attic. Sometimes, especially with older systems, the filter is located inside the furnace itself, next to the blower motor. And some systems have a central filter grille installed in a wall or ceiling. The grille swings open, revealing the air filter.

What can happen if I don’t change my air filter regularly?

Air filters have a relatively simple function, but they can’t do their job effectively if they are not clean. Many different problems can arise from a dirty air filter, such as:

• Dust and other airborne particulates build up on the mechanical components (i.e. fan blade and motor).

• Allergens and dirt accumulate on the duct work walls.

• Dirt can block or clog the HVAC coils.

• The same coils can freeze due to lack of air flow.

• The HVAC system cannot perform efficiently and increase your monthly energy bills.

• A filter that doesn’t fit right allows dirt to bypass the filter.

How do air filters affect IAQ (Indoor Air Quality)?

Air filters primary job is to screen out any particles, even microscopic ones, from going through the HVAC system. Home-air pollutants can be particulate matter or even gas. There are many things that affect your home’s IAQ including:
• Dust
• Dust Mites
• Spores
• Mold
• Viruses
• Pollen
• Pet Dander
• Hair
• Bug Parts
• Lint
• Ash
• Pesticides
• Tobacco, wood, or food smoke
• Paint or other vapors
• Cleaning product fumes

Do you use the same filter for Heat and Air Conditioning?

Yes. The term HVAC stands for Heating, Ventilation, and Air Conditioning meaning it serves as a furnace and AC unit. The most common systems have hot and cold air that travels through the same ducts so they use the same filter, even though you may hear them called furnace filters or air conditioning filters. Filters can be found between the duct work and the mechanical components where the air travels in the air handler/exchange system.

Which filter is best for my home and family?
Selecting the right filter for your home and family takes a little self- assessment. Consider asking yourself the following questions to guide your decision. Any of the answers to them might affect which filter you decide to purchase – as well as how often you will change it. 

• How many people currently reside in the house? 

• Is the house cleaned on a regular basis (especially dusting and vacuuming)? 

• Are you in an area with open fields, roads, or other dusty areas? 

• Are there fur-babies in the house? 

• Does anyone in the house smoke? 

• Are you or other family members allergy sufferers? 

• How do you feel about the air quality in your home in general?
How do I change air filters?
It is just as important to correctly install your filter as it is to change it. It is easiest to change your filter if your unit isn’t active, if it is, turn it off. After locating the air filter housing, look at how it is sitting in the slot and make note of the direction the arrow is pointing. You may even want to consider marking the arrow direction on the frame of the housing with a permanent marker to make sure you always put it in the correct air-flow direction. Then, pull the old filter out, match up the arrows on the frame and the clean filter and slide the new air filter into the housing. That’s it!
What size filter should I get?
In addition to the directional arrow on the air filter, you will also see numbers denoting the filters width, length, and thickness. This is the air filter size your HVAC unit takes and should be the size you always order. Using the correct-sized filter is also important so your filter can do its job properly and not allow dirt and debris to bypass the filter. It should fit in the slot snugly, with no major gaps on the size and you should never have to force it into the housing.
Do air filters help me save money?
Yes, they do! The Department of Energy reports that replacing dirty filters with clean air filters can reduce your energy consumption up to 15%. When you combine that with the fact that your HVAC system is responsible for nearly half your energy usage, there is a potential savings of 7.5% each month. So, if your energy bill is $100/month, you could save $7.50 on each monthly bill just by changing your air filter! Is your energy bill in the $200, $300, $400 range? You’re looking at even more savings – upwards of $30 every month.
What are the different types of furnace filters?

Furnace filters come in many shapes and sizes so you can find the best solution for your air quality needs that fits your HVAC system. Filters protect delicate system components from airborne contaminants that could cause mechanical failures. By removing these contaminants from your indoor air supply, they also work to improve air quality.

The different types of furnace filters include:

Fiberglass/Synthetic Filters

Fiberglass or synthetic filters are a cheap and disposable option for your furnace. They catch up to 80% of particles 50 microns and larger and 25% of particles between 3 to 10 microns. Considered minimum protection, fiberglass/synthetic filters prevent dust and dirt from building up on heat exchangers, fan motors, and other surfaces. The larger particles are trapped and eliminated, so your furnace components remain clean. They allow your system to have maximum airflow but don’t filter harmful contaminants affecting your health.

Polyester Filters

Polyester filters are made using the highest quality materials available and are median-sized. They trap and eliminate 80% to 95% of particles 5 microns or larger. A polyester filter costs fours time more than the average fiberglass/synthetic filter, but it offers more protection against pollutants that cause health issues.

Electrostatic Filters

Electrostatic filters use self-charging fibers to attract particles out of your air. You can purchase disposable or washable electrostatic filters depending on the requirements of your furnace. Washable versions offer a MERV rating between 4 and 10 and last considerably longer than the average filter. Maintenance on a washable filter requires soap and water to wash the filter and letting it completely dry before reinstalling it. If you install it before it completely dries, you run the risk of mildew and mold growth.

Pleated Filters

A pleated filter offers high-efficiency results by trapping particulates 0.3 micron in size, such as bacteria and viruses. Pleated filters are more efficient and last longer compared to fiberglass/synthetic filters. They eliminate more pollutants from your air without sacrificing airflow within your system.

HEPA Filters

High efficiency particulate air, or HEPA, filters provide high-end filtration by trapping up to 99% of particles 0.3 microns or larger. Even though they are excellent at eliminating indoor pollutants and create a healthier environment in your home, they can drastically reduce your system’s airflow, costing more money in energy usage.

How can I tell if my air filter needs changing?

Air filters need to be changed on a regular basis to be effective. The manufacturer will recommend the frequency the filter should be replaced, but other factors may warrant a change sooner. Watch for these signs that your furnace filter needs changing:
• The filter is noticeably gray in color, and you can see dirt and dust built up on the filter media.
• Your home is dustier than usual.
• Your heating or cooling system is cycling longer than it usually does.
• Your current filter has been in use longer than the manufacturer’s recommendation (anywhere from one to six months, depending on your filter)

What are MERV ratings?

Minimum Efficiency Reporting Value (MERV) ratings indicate how effective air filters are at trapping airborne particulates, such as dust, dirt and pollen. The higher the MERV rating, the fewer particles are able to pass through. Listed below is an explanation of the various MERV ratings and the effectiveness of the filters that fall into each category:

• 1 to 4 — Air filters with MERV ratings between 1 and 4 are entry-level filters, and are typically made of spun fiberglass. Washable filters that come bundled with HVAC systems are typically rated at 4. These filters are sufficient only for catching pet hair, carpet fibers and similar debris.

• 5 to 8 — Filters with this rating offer improved filtration, and are capable of trapping particulates between 3 and 10 microns. This includes mold spores, pet dander and certain types of pollen.

• 9 to 12 — Filters in this range are considered to provide superior filtration, and can trap particles between 1 and 3 microns, which includes lead dust and vehicle emissions.

• 13 to 20 — These top-grade filters are rated to trap very small particles such as tobacco smoke, bacteria and particles that are less than 0.30 microns in size.

Does a higher MERV rating affect airflow?

Generally, a filter with a higher MERV rating will reduce airflow. However, there are many other factors at play such as the size of the filter and the type of blower motor in your HVAC system.

Filters for central HVAC systems are usually the primary form of particle removal for residential and commercial buildings.

Much attention is giving to the filter’s efficiency at removing particles and cleaning the air. But using a filter also introduces a barrier that can cause reductions in airflow.

Could using stronger filters lead to inadequate airflow? It seems obvious that a stronger air filter will reduce the airflow in your HVAC system. However, considering the airflow reduction caused by a high MERV filter is usually an afterthought for most homeowners.

Even if high MERV filters are used, will it substantially affect your system? One study found that while there is a link between using high-efficiency filters and increased energy use, for most residential systems the impact is not significant.

When it comes to air filters affecting airflow, there are three factors at play:

• The size of the air filter. The size of the air filter has a huge impact on how much airflow goes through your HVAC system. This is mainly because a filter with a large face area will minimize pressure drops.

• The efficiency of the air filter. The MERV rating has an indirect impact on airflow. Generally, filters with higher MERV values will have less airflow.

• Blower motor type. Whether you have a PSC or ECM blower motor has implications on airflow.

When faced with filter pressure drops PSC motors will maintain less airflow but use the same amount of energy.

ECMs will maintain the same airflow but use more energy.

This is very important because if your system has an ECM blower motor, then you will see likely see minimal airflow impact when using a high MERV rated filter. Instead, your blower motor will use more energy to maintain airflow.

How does filter size affects airflow?

The size of your air filter has a huge effect on the airflow through your HVAC system. Assuming all else is equal, the larger the filter, the more airflow through your HVAC system.

This applies to both the length, width, as well as depth of the filter.

In a pleated filter, the deeper the filter, the longer its pleats. The surface area of the filter that is used for filtering air is called the face area.

A filter with more face area is effectively a larger filter size. So this means that the filter will produce less pressure drop.

How does a filter's MERV rating affect pressure drop?

The pressure drop across an air filter will determine how negatively the filter affects airflow. Higher pressure drop = less airflow.  

The Air Conditioning Contractors of America assumes that the pressure drop across a filter is 0.10 in. w.c. However, one study found that actual pressure drops in home installations were on average 0.28 in. w.c. 

Even though stronger filters produce higher pressure drops, there are some ways that airflow can be maximized while using high MERV-rated filters. 

In fact, even filters with high MERV ratings can be used in some systems with a minimal pressure drop. The trick is that the filter’s face area needs to be maximized in order to obtain the lowest filter pressure drop as possible. 

There are a couple of different ways to maximize your air filters’ face area: 

• Increase the size (width) of your air filters. This includes maximizing the cross-sectional area of the slot that you put your air filter in. 

For instance, if an air filter’s slot is in the return register of an HVAC system, some homeowners might elect to modify the return register to a larger size to accommodate a larger filter. 

• Use an air filter with a larger depth. For instance, a 2-in. pleated air filter will have a larger face area than a 1-in. pleated air filter. 

The air filter slot on your home’s HVAC system determines the depth of the air filter that you can use. In order to use a deeper air filter, your air filter’s slot will need to be large enough to accommodate the filter.

How does Total External Static Pressure (TESP) affects airflow?

The total external static pressure or TESP is the pressure difference across your entire HVAC system. The total external static pressure is measured by taking the difference of the pressure between the supply and return registers.  

Why is TESP important? It is an indicator of how much airflow is going through your system. Generally, higher TESP = more airflow.

How do air filters contribute to total external static pressure?

Air filters contribute to TESP by reducing the total external static pressure in the system. This means that using an air filter will reduce the amount of airflow in your HVAC system. 

Most residential homes are designed to have no less than 0.5 in. w.c. of TESP. Since the air filters in many residential homes contribute to more than half of that pressure, it is clear that air filters are responsible for a large part of the pressure drop in an HVAC system.

Since using an air filter is not optional, you’ll need to find a filter that meets both your air filtration needs and airflow requirements. 

The diagram below shows a typical pressure distribution of a residential HVAC system.

How different types of blower motors affect airflow?

The type of blower that you have in your furnace or air conditioner will largely determine if there will be a reduction of airflow in the system.

Permanent Split Capacitor (PSC) Motor

Permanent split capacitor (PSC) motors are used in most standard, economy-priced furnaces. In the presence of airflow restriction, PSC motors will consume relatively the same amount of power but provide less airflow.

Even though the amount of power that a PSC consumes remains unaffected, the reduction in airflow can cause an overall increase in energy use. This is due to increased runtimes from the reduction of heating/cooling capacity.

When using a high MERV rated filter, you will likely see a slight reduction of airflow when using a PSC motor. As the filter gets dirty and more airflow is restricted, the PSC motor will deliver even less airflow.

Electrically Commutated Motor (ECM)

Electrically Commutated Motors (ECM) are newer and more energy-efficient than PSC motors. ECMs consist of a brushless DC motor combined with a microprocessor to control its speed.

The result is that when airflow restriction is introduced, the ECM will speed up to maintain the same amount of airflow. Doing so increases the energy use of an ECM.

However, ECMs are already very energy-efficient, so they will on average use less energy than a PSC, even with a dirty filter.

What is an activated carbon filter?
An activated carbon air filter consists of a bed of carbon encased in a cloth or mesh-like material. These filters remove gaseous compounds from the air. Molecules such as odors and volatile organic compounds (VOCs) are extremely tiny and will slip right through a normal air filter. Activated carbon filters trap these molecules and remove them from the air in your home.
How does an activated carbon filter work?

The activated carbon in carbon air filters is an extremely porous substance. In fact, it is so porous, that typical activated carbon has a surface area of 1000m2 per gram. That’s one square kilometer for every gram of material!

Why is the surface area of activated carbon so important? The more surface area that it has, the better chance that the activated carbon will have to capture molecules.

Activated carbon air filters remove gases from the air by trapping them in a lattice of carbon molecules. This process is called adsorption.

Carbon air filters and the adsorption process

As air flows through a carbon filter, all the molecules in the air flow through the filter as well. As the molecules flow through the filter, they pass through the activated carbon. Some of the molecules become trapped in the carbon due to the process of adsorption.

Adsorption happens when a particle gets stuck to the surface of a material. This is an important concept to understand for carbon filters. The more surface area that is available, the better chance that a particle will have to get stuck to the carbon filter.

Adsorption is like absorption, but there is one distinct difference. Adsorption happens when a particle gets stuck to the surface of a material. Absorption happens when a particle gets stuck inside of a material.

What MPR filter do you need?

For most residential homes, a filter with an MPR 600 rating will be sufficient to filter out most dust, pollen, and mold. 

If you’re familiar with the MERV rating scale, then an MPR 600 filter is roughly equivalent to a MERV 7 air filter. However, an MPR 600 air filter exceeds the requirements of MERV 7 air filters since they are tested to filter out more micro particles than a standard MERV 7 filter.

Frequently asked questions on air purifiers

Do air purifiers remove odors?
An activated carbon filter is very effective at removing odors. They can eliminate smells from smoke, pets, food, garbage, and even baby diapers. Other types of filters, such as HEPA filters, are not as effective in removing odors as they are in eliminating pollution particles.
Will an air purifiers cure my asthma or allergies?
No. Air purifiers prevent asthma symptoms and allergies by filtering out airborne allergens like pollen, dust, and animal dander. However, they do not cure asthma and allergies. Purifiers are more of a preventive measure; not a cure.
What is the best air purifier for someone with asthma?
The best air purifier for someone with asthma is one with both a HEPA filter and an activated carbon filter. An air purifier with both filter types will remove particles and gaseous pollutants that can cause asthma.
Are there side effects to an air purifier?
Generally speaking, there are no side effects. However, there are a few purifiers on the market that use electrostatic precipitators and ionizers; these *may* emit small levels of ozone. Before buying an air purifier, make sure to check the product specifications.
How much does it cost to operate an air purifier?
It depends on a few things. For example, although electricity is a secondary cost associated with running an air purifier, the energy efficiencies of the device will impact how much it costs to operate. You’ll also need to buy new filters from time to time. If you invest in a high-quality HEPA filter, you will have to change it every 3-5 years. There are cheaper filters available, but they’ve been proven to be less effective and need to be replaced more often.
How do I know if my air purifier is working?

Allergies acting up? That could be a sign that your air purifier isn’t working at full speed. 

Check the assembly for any dust or dirt in the pre-filter after cleaning it. If you don’t see anything obvious that could be causing a problem, that may be a sign that there’s a more significant issue with your air purifier. For a clearer understanding of its effectiveness, you may need an air quality monitor. 

The lifespan of an the filters varies, depending on where you live and the frequency of use. In reality, there is no “one size fits all” when it comes to knowing when to replace an air purifier. We’ve put together a simple tutorial that will help you determine if you’re air purifier is working properly: 

Will an air purifier protect my entire house?
Sometimes. The packaging will tell you the maximum area (per square foot) that the air purifier can protect. Comparing this square footage to that of your home should help you better understand what’s needed.
Can I open my windows in a room where an air purifier is running?
In short, yes. Opening or closing a window doesn’t matter—an air purifier is going to purify the air regardless. That said, keeping the doors and windows closed will help your air purifier to maximize its effectiveness since external pollutants aren’t able to come in.
Where should I put my air purifier?
Place your air purifier in a room where you spend a lot of time, like your bedroom. Make sure that there is no obstruction in the airflow of the air purifier. There shouldn’t be anything placed in front that would obstruct the indoor air to pass through it. 
How often should I run my air purifier?
For larger spaces, you’ll need to run the purifier for more extended periods. Smaller rooms generally take less time to clean. We recommend that you run the purifier at regular intervals so that lingering pollutants don’t accumulate. To get the best results from your air purifier, consider pairing it with an air quality monitor.
Do air purifiers make noise?
For any air purifier to be effective, it has to move the air. As such, there is no way to do this silently (despite what’s been advertised). However, with most air purifiers, there’s a noise level setting that can be adjusted based on preference.

General frequently asked questions

Can I install an R-410A mini-split unit?

No. Section 608 Technician Certification is required for activities that could reasonably be expected to violate the integrity of the refrigeration circuit. Adding or removing refrigerant from a mini-split as part of installation, and/or connecting or disconnecting hoses or pre-charged lines requires a Section 608 technician certification. Activities reasonably expected to violate the integrity of the refrigerant circuit include but are not limited to: attaching or detaching hoses and gauges to and from the appliance; adding or removing refrigerant; adding or removing components; and cutting the refrigerant line.

How can I troubleshoot my own system?

Nobody wants to pay for unnecessary service calls. If your heating or cooling system isn’t working, or isn’t performing as it should, start by performing a few simple checks yourself – you might just save time and money. 

• Are all on/off switches in the correct position? Check indoors for heating systems, outdoors for air conditioners.
• Are any fuses or circuit breakers blown?
• Are your thermostat settings correct? For cooling, ensure that your system switch is in the COOL position; for heating, make sure it is set to HEAT or Auto.
• Are the batteries in your thermostat replaced?

Why is preventative maintenance important?

Your furnace, air conditioner, and heat pump are precision-engineered, heavy duty systems which undergo long periods of intensive operation. No matter how well built, they can be expected to wear over time – and the lack of regular maintenance can accelerate that process. By changing filters, performing cleanings, and conducting other recommended regular maintenance as required, you extend the life of your systems and increase their efficiency.

How often should I change my thermostat batteries?
Change your thermostat batteries at least once per year, or more often if you notice any problems with inconsistent operation. Note that low batteries can cause your furnace or air conditioner to operate inconsistently, or not at all.
How do I clean my exterior air conditioning unit?
Clean your air conditioner’s outdoor unit as needed, but it is a good rule of thumb to clean it both at the beginning and the end of the operating season. With the unit switched off, use a garden hose to clean the exterior surface. For extremely dirty units or if dirt has collected in the air conditioner coils, contact Premier to schedule maintenance.
What would void my manufacturer's warranty?

There are a number of circumstances that can void a manufacturer’s warranty:

• Failure to perform inspections, maintenance, and cleaning as required
• Use of counterfeit, non-standard, or non-authorized parts or accessories
• Installation of any system or component by anyone other than a licensed, certified contractor
• Relocation of heating/cooling equipment from its original position in your home 

Your manufacturer’s warranty provides important protection for you in the event of a breakdown. If you are unsure about any aspect of repair, maintenance, inspection, or installation of your system, contact Premier for a consultation.

What type of fuel should I use to heat and cool my home?

Your primary options include natural gas, oil, and electricity. We’ll help you select the best solution for your needs and budget. 

Gas furnaces are the most popular fuel for home heating in the United States. If you have the infrastructure in place, natural gas is delivered to your home through pipes. This fuel is cleaner, more convenient, and often more cost effective than oil. 

Still, oil is a viable option if you don’t have natural gas lines hooked up. Oil produces heat faster than gas, has no carbon monoxide risks, and keeps your home comfortable all winter. 

Electricity is the most versatile option. A heat pump, ductless mini-split, or geothermal system allows you to heat and cool your home with a single piece of equipment. These options also open the door to solar-powered home heating and cooling to help you do your part for the environment.

Will my home warranty cover my HVAC system?
While the homeowner policy typically covers the actual structure of your home, there is often an additional home warranty available that will cover appliances such as those needed for your heating and cooling system. Some research into the specifics of the home warranty that your realtor is offering will be key in making the right decision.
Do I need to replace my HVAC system?

Most HVAC systems have a “life expectancy” of 14-16 years. Repairing a system is certainly an option, but it’s recommended that you spend less than 50 percent of the cost of a new system on repairing the old one. Considering the Seasonal Energy Efficiency Ratio (SEER), or energy efficiency, of your system will also help you make the right decision. 

How long will my HVAC system last?

A heating or cooling system is a significant investment, and it only makes sense to get as much use out of it as possible. In general, most HVAC systems will last from 15 to 25 years, but depending on the type of system and other contributing factors, that estimate can be highly variable. Even with HVAC maintenance and regular repairs, eventually even the best boilers, furnaces, heat pumps, and air conditioners today will run their course over time.

How often do I truly need to maintain my HVAC system?
Like most other things, your HVAC system will perform better and last longer with regular maintenance. We recommend making a habit of booking an bi annual maintenance appointments ahead of the heating and cooling seasons where your contractor can inspect your heating and air conditioning systems and address indoor air quality.
I'm ready to upgrade my HVAC system. Where can I find the rebates available in my area?

As you consider your options, keep in mind that high-efficiency units typically have a higher upfront cost but lower operating costs, and may qualify for additional rebates. Find out more at

Do bigger air conditioning units perform better?

Not necessarily. It is important to purchase an air conditioner that is the right size for your home. If you buy an AC unit that’s too big, it will cool your home faster, but it will also be less efficient and will not eliminate humidity well enough. It will have short run cycles. While it will cool the air quickly, it will shut off before it blows enough air across the indoor coil to drain water from your system. This will leave too much moisture in the air, which can lead to mold and mildew in your home. 

Your system starting and stopping more often will cause it to use more energy and wear down faster. Longer run cycles are more efficient.

What size heating/cooling system do I need?

A system that is too large will cool or heat your house quickly, but you may not feel comfortable. That’s because it will satisfy the thermostat before it can adequately remove sufficient moisture from the air during the cooling mode, leaving you feeling sticky and humid. This could even lead to moisture and mold problems. And, the stress of short-cycling (too many starts and stops) will shorten the life of your equipment and increase your heating and cooling bills. 

On the other hand, a system that is too small just cannot get the job done, especially in extreme weather conditions. The air conditioner will run constantly in the Summer and the furnace will do the same in the Winter. 

But a correctly sized system isn’t just based on the size of the structure. Many factors go into determining the size of the system. Including type of house and walls, type and size of windows, insulation, basement and attic conditions, house orientation, and so on. A comfort consultant must visit the house and take detailed measurements and notes while conducting the survey.

Frequently asked questions on IAQ

Why is Indoor Air Quality an issue?
According to the National Safety Council, people, on average, spend about 90 percent of their time indoors. Of that 90 percent, 65 is spent at home and to make matters worse, those who are most susceptible to indoor air pollution are the ones who are home the most: children, pregnant women, the elderly, and those with chronic illnesses. Children breathe in 50 percent more air per pound of body weight than adults do. EPA studies have found that pollutant levels inside can be two to five times higher than outdoors. After some activities, indoor air pollution levels can be 100 times higher than outdoors.
Can the air inside our homes be bad for us?

In an attempt to conserve energy, buildings are increasingly being constructed more and more airtight.  Specific to homes, storm windows, insulation, caulking and weather stripping cracks are a few ways we have managed to keep air, hot or cold, from escaping.  Unfortunately when air is trapped in a building, pollutants are also trapped. 

What are the sources of pollutants?
According to the National Safety Council, there are many sources of pollutants in the home. Obvious ones are chemicals, cleaning products, and pesticides. Less obvious are pollutants caused by such simple tasks as cooking, bathing, or heating the home. Fortunately, there are easy steps that everyone can take to reduce the potential for indoor air pollution and to improve the quality of the air they breathe.
What are the different types of pollutants?
There are three different types of indoor air pollutants.  Particulates: dust, pollen, dust mites, animal dander, carpet fibers, and lint.  Micro-organisms: mold, influenza, fungi, viruses, bacteria, and germs.  Toxins (gases):  benzene chemical vapors, formaldehyde, carbon monoxide, paint, pesticides, carpet fumes, pet odors, ozone, cleaning vapors, and smoke.
How to know if the air inside your home is dangerous to your health?

According to the National Safety Council, it is difficult to determine which pollutant or pollutants are the sources of a person’s ill health, or even if indoor air pollution is the problem. Many indoor air pollutants cannot be detected by our senses (e.g., smell) and the symptoms they produce can be vague and sometimes similar, making it hard to attribute them to a specific cause. Some symptoms may not show up until years later, making it even harder to discover the cause. Common symptoms of exposure to indoor air pollutants include: headaches, tiredness, dizziness, nausea, itchy nose, and scratchy throat. More serious effects are asthma and other breathing disorders and cancer. 

How does this affect children?
According to the National Safety Council, children may be more susceptible to environmental exposures than adults and, because of their developing systems, particularly vulnerable to their effects. Asthma is a case in point. About 4.2 million children in the United States, and more than 12.4 million people total, are affected by asthma each year. A recent study, published in the American Journal of Respiratory and Critical Care Medicine concluded that 65 percent of asthma cases among elementary school-age children could be prevented by controlling exposure to indoor allergens and environmental tobacco smoke (ETS). By controlling biological contaminants (e.g., dust mites and cat allergens), asthma cases could be reduced by 55 to 60 percent.
How can I find an Indoor Air Quality system that's right for my home?
Here at Premier Heating and Cooling, we have an entire team dedicated to improve the quality of life for our customers starting with the air you breathe.  We offer a variety of solutions to suit your individual needs to improve your indoor air quality.  Our process consists of addressing your concerns, in home consultation and installation.   A phone call is all that stands between you and improved home indoor air quality.  Give us a call today and breathe easier tomorrow!
What would be involved in an Indoor Air Quality consultation?
At your schedule appointment time, our IAQ Consultant will arrive at your home, driving a clearly marked Premier Heating and Cooling vehicle, with a fully displayed identification badge. Our IAQ Consultant will walk with you throughout your home to observe existing conditions while listening to your experiences and concerns about your indoor air quality needs. We use current State of the Art Technology Sensor Equipment to determine the particulate count of various pollutants that are in your indoor atmosphere. Our IAQ Consultant can then provide you with information based on the Micron Size of the pollutants, not only what volume of these exist but also what type of pollutants, such as Pollen, Dirt, Dust, Viruses, and Bacteria as well as Carbon Monoxide. Our IAQ Consultant will sit with you to prepare the proposal based on the needs you have expressed. This proposal will state the products and the exact cost figures of each.  At this time, you will have the opportunity to sign the agreement, and you will be given a date of installation based on your schedule.
What would be involved in the installation of Indoor Air Quality products?

You will receive a reminder phone call from our office the night before your appointment, if we are unable to reach you, we will leave you a message. Our Installation Team will arrive at your home in uniform, driving a clearly marked Premier Heating and Cooling vehicle and introduce themselves to you. The Installation Team will begin the process of installing your IAQ products. Upon completion, you will be asked to sign the service ticket and any other paperwork that is applicable to your installation. Our Installation Team will clean up and address any final questions you may have. 

How can I improve the Indoor Air Quality in my home?

Since you probably spend a majority of your time indoors, the air quality here is a major factor in determining your overall health. To help you and your family breathe easier, make an effort to improve IAQ. 

• Inspect your air filter monthly and replace it at least every six months.
• Install a whole-house humidifier to increase relative humidity during the dry winter months.
• Install an air purifier and or HEPA filtration to trap airborne contaminants.
• Install a heat recovery ventilator for fresh air without high energy bills.
• Use large surface area 4″ Media Filters
• Consider using UVC lights to combat any microbial growth
• Run the exhaust fans in the bathroom and kitchen when you shower and cook to vent moist air outside.
• Clean your air conditioner’s drip pan throughout the summer to prevent mold growth.
• Reduce your use of chemicals, artificial fragrances, and aerosol products indoors.
• Change the batteries in your smoke and carbon monoxide detectors once a year.
• Vacuum weekly with a vacuum cleaner that features a HEPA filter.
• Look for low- or no-VOC paint for home renovation projects.
• Never idle your car in the garage, even with the door wide open.

Frequently asked questions on UV-C

What is UV-C?
UV light comprises a segment of the electromagnetic spectrum between 100 and 400 nm, corresponding to photon energies from 3 to 124 eV. The UV segment has four wavelengths, labeled: UV-A (400 to 315 nm); UV-B (315 to 280 nm); very high energy and destructive UV-C (280 to 200 nm); and vacuum UV (200 to 100 nm). 

UVC’s germicidal or germ-killing effects are well proven. The 253.7 nm electromagnetic waveform is well absorbed by DNA and RNA (the genetic code for all lifeforms), changing its structure. This damage inhibits the ability of the affected cells to reproduce, meaning that they cannot infect and are no longer dangerous.

Is UV-C harmful?

We’re exposed to parts of the UV spectrum while outdoors. Generally, excessive UV exposure can produce adverse effects depending on wavelength, type and duration, and UV response differences between individuals. The three basic wavelengths: 

— UV-C – includes the germicidal wavelength of 253.7nm and is used for air and water disinfection. Human overexposure causes temporary skin redness and harsh eye irritation, but no permanent damage, skin cancer, or cataracts.

— UV-B – is a narrower but more dangerous band of UV. Prolonged exposure has been associated with skin cancer, skin aging, and cataracts (clouding of the lens of the eye).

— UV-A – is more predominant outdoors than the other two. It helps to tan our skin and is used in medicine to treat certain skin disorders. It is generally a harmless wavelength.
UV-A, B and C will damage collagen fibers and accelerate skin aging. Generally, UV-A is the least harmful; UV-B contributes to DNA damage and cancer. It penetrates deeply but does not cause sunburn. Because of no reddening (erythema), it cannot be measured in SPF testing. There is no good clinical measurement of UV-B blocking, but it is important that sunscreens block both UV-A and B. UV-C however, penetrates superficially and has not been associated with long-term tissue effects.

How does it affect germs?
Microorganisms are simple organic structures that readily absorb the UVC wavelength, causing photo-disassociation (destruction). A microbe’s DNA (deoxyribonucleic acid, is first to be adversely affected due to its weaker molecular bonds. 

In hundredths of a second, it suffers irreparable damage. The subsequent loss of genetic instructions causes cell death and/or the inability to replicate, rendering them harmless. Continuous exposure causes uninterrupted degradation, such as the sun does, only significantly faster.

Can UV-C save energy?
Yes, in literally thousands of controlled tests, organic materials build-up on coils was removed with UVC to provide two eventual results: 1. the pressure drop across a coil declines to increase airflow. 2. the leaving air wet-bulb temperature differential increases. Energy savings are therefore through increased heat absorption (transfer), reduced air horsepower (or increased air volume) and/or reduced run time, including at a condenser. These reductions and increases always manifest themselves in some form of energy-saving work.
Does UV-C kill microbial growth and pathogens?

The CDC [v] and ASHRAE have recommended UVC as one technology that can “reduce the risk of dissemination of infectious aerosols in buildings and transportation environments.” [vi] ASHRAE has recognized that the 253.7 nm germicidal C-band wavelength inactivates virtually all microorganisms living on HVAC/R surfaces with a kill ratio of 90 percent or higher, depending on UV-C intensity, length of exposure, lamp placement, and lamp life cycle. In fact, a CDC-funded study conducted in two hospitals found that UVC reduced the total number of colony-forming units of any pathogen in a room by 91 percent. [vii]

Science has yet to find a microorganism that is immune to the destructive effects of UVC, including superbugs and all other antibiotic-resistant microbes associated with healthcare-associated infections.

[v] CDC. COVID-19 Employer Information for Office Buildings (September 11, 2020). Retrieved from

[vi] ASHRAE Position Document on Infectious Aerosols (April 14, 2020). Retrieved from

[vii] Anderson D. J., et. al. (2013) Decontamination of Targeted Pathogens from Patient Rooms Using an Automated Ultraviolet-C-Emitting Device.” Infection Control & Hospital Epidemiology. Retrieved from

Can UV-C Inactivate the virus that cause COVID-19?

Researchers now know that the 254 nm germicidal wavelength can inactivate the genetic material in the SARS-CoV-2 virus [i]. Moreover, when aerosolized the COVID-19 causing virus is likely to be more susceptible to UVC damage than other coronaviruses such as SARS-CoV-1 (that led to the 2003 severe acute respiratory syndrome) or MERS-CoV2 [ii] (that caused the 2012 Middle East respiratory syndrome). 

It is important to note that science has not found any microorganism that can withstand the destructive effects of the UV-C germicidal wavelength, including superbugs and other antibiotic-resistant germs. In fact, viruses and bacteria cannot develop a resistance to germicidal UV because it uses energy to kill, rather than synthetic or chemical elements. Today, there are several approaches to using this decades-old technology to reduce microbes in the air and on surfaces, including airstream disinfection (also known as in-duct) and upper-room decontamination. 

Germicidal UV-C air disinfection systems are installed in a building’s HVAC ductwork to disinfect moving airstreams before they reach employees. Kill ratios over 99 percent on a first-pass basis have been demonstrated by the Environmental Protection Agency (EPA) and the National Homeland Security Research Center. As air is re-circulated, concentrations of infectious pathogens are further reduced by each subsequent pass (“multiple dosing”). 

Upper-room UVC is the oldest disinfection application of the germicidal wavelength for airborne inactivation and is recommended for improved control of highly contagious airborne diseases such as Tuberculosis by the U.S. Centers for Disease Control and Prevention and the National Institute for Occupational Safety and Health. 

[i] National Academies of Sciences, Engineering and Medicine. Does ultraviolet light kill the coronavirus? October 2020. Retrieved from 

[ii] Environmental Protection Agency and National Homeland Security Research Center. Biological Inactivation Efficiency of HVAC In-Duct Ultraviolet Devices. Technical Brief. Washington, DC: EPA;2006. (EPA/600/S-06/034). Retrieved from

How effective are UV-C lights at getting rid of coronavirus?

Scientists know that coronaviruses are transmitted via air and direct contact [iii]. At the same time, research has shown that exposure to the UVC waveform (253.7 nm) is a practical and cost-effective method of inactivating airborne viruses, mycoplasma, bacteria, and fungi on clean surfaces. [iv] 

Because of the extended incubation period for some of these diseases, people can spread the virus before anyone knows they are contagious and, more importantly, before anyone can take precautions. Therefore, it is incumbent on facility managers to use preventative infection control measures such as germicidal UVC to mitigate the potential spread of airborne diseases.

[iii] Kowalski, W. (2015). SARS Coronavirus UV Susceptibility. Retrieved from 

[iv] Department of the Army. (2009) Safety standards for microbiological and biomedical laboratories. Retrieved from

Does UV-C replace filters?

No, a UVC fixture is an air conditioning component that is in addition to other system parts. These include the coil, heating core, fan, dampers, humidifiers, filters, etc. All are designed to do some form of work within the air handler a UVC fixture is just one of these components. 

While antibacterial UVC applications have improved indoor air quality for decades, it was the COVID-19 pandemic that took the technology’s use in the eyes of building managers from energy savings to infection mitigation. Just as no one would operate an HVAC system without air filters—the time is near when no one will operate HVAC/R systems without UVC installed.

How do you size UV-C application?
For IAQ, improved heat transfer, reduced maintenance and odor, an approach used for well over ten years is to put the lamp row centerlines on 30-inch to 45-inch centerlines. Most highly regarded manufacturers have software that can size these types of installations, and more. Only consult one of these reputable manufacturers when sizing infectious disease agent applications.
Is UV-C hard to install?

Not at all. Simple installation instructions are provided along with layout drawings populated with all the necessary dimensional specifics. Product designs are emerging that allow installation of UV-C in AHU’s in under an hour in many cases. This also includes fan-coil, unitary and rooftop units, the hardest systems to keep clean. Consult a reputable factory and then involve them in any infectious disease application. 

Is fiberglass affected by UV-C?

There are many different materials found in HVACR systems, from metal to plastic, to glass to synthetic media, and all can be impacted differently by UVC. While metal and glass are impervious to UVC energy (standard glass, in fact, blocks the UVC wavelength), plastic and synthetic media (e.g., air filters) can be affected. Applying aluminum foil tape to plastic and rubber materials (electrical wires) will protect them from direct UVC exposure (and help reflect UVC energy further into the plenum). 

Additionally, labeling wires may be wise—as they can deteriorate and become cracked or brittle when exposed to UVC—this will allow you to differentiate the yellow wire from the white. Likewise, you should not install UVC lamps near synthetic air filters typically found in residential and commercial HVACR systems to UVC energy. 

We recommend the use of “UV-Safe” or “UV-Resistant” filters, typically “glass” based filters. Finally, fiberglass insulation holds up quite well to UVC. While UVC energy will not affect the “glass” component in the insulation, it can affect the adhesive binders that hold the fiberglass together, but overall the fiberglass insulation will not degrade when left in place due to the glass content. We have had field reports of significant degradation of ArmaFlex™ tube insulation or 
closed-cell foam insulation when exposed to UVC energy. Some manufacturers provide coatings that act as a sacrificial layer between the UVC energy and the foam material (metal tape can also accomplish the same protection). 

How do you dispose of used lamps?

Currently, most users would dispose of them as they would any glass trash, such as their fluorescent lamps. Large fluorescent lamp users follow EPA and state guidelines, and UVC lamps would then fall into those same guidelines. If you have a fluorescent lamp disposal program in place, UVC lamps would simply fall into that same program. 

When do you change lamps?
For infectious disease applications, change-out should be performed using an output measurement device such as a radiometer, while following factory specifications and/or recommendations. For IAQ or mold control, large installs might benefit from a radiometer to preclude premature change-outs. Changing lamps when their output decreases by 20 percent are common, this usually occurs in about 12-15 months. So for installs with no radiometer, re-lamp at least annually and replace burn-out as soon as possible.
Can viruses spread through HVAC ducts?

Because most viruses can be transmitted via air and direct contact, it could be presumed that HVAC systems can inadvertently broadcast the infection, increasing its spread. Therefore, facility managers should consider employing both upper-room UVGI and HVAC germicidal fixtures to ensure the greatest mitigation practical for control of microbes and airborne microorganisms in communal spaces. 

Airborne droplets containing infectious agents can remain in room air for 6 minutes and longer. Upper-room UVC fixtures can destroy those microbes when they are exposed to the UVC energy in a matter of seconds. Kill ratios up to 99.9 percent on a first-pass basis have been modeled and, as air is recirculated, concentrations are further reduced by each subsequent pass (“multiple dosing”). 

Surface-cleaning UV-C systems provide 24/7 irradiation of HVAC/R components to destroy bacteria, viruses and mold that settle and proliferate on HVAC coils, air filters, ducts and drain pans. UVC prevents these areas from becoming microbial reservoirs for pathogen growth that can eventually become airborne and circulated by HVAC systems.

A system installed for HVAC surface irradiation, while not specifically designed for it, can also provide first-pass kill ratios of airborne pathogens of up to 30 percent, along with the primary benefits of restored cleanliness, heat-exchange efficiency and energy use.

Frequently asked questions on ductwork

Why are my ducts popping and banging?

One of the main causes for these loud noises are differences in pressure between the supply and return ducts. Another common cause is expansion and contraction due to changes in temperature. 

Oil Canning – When the walls of your air ducts move in and out due to pressure differences, you may hear a rumbling, popping sound. This is often referred to as “oil canning.” 

Expansion and Contraction – If you only hear the banging and popping noise when you turn on the furnace, it could be because you have warm air flowing through cold ducks, which can make the metal expand and “pop.” If you hear creaking, your ducts may be expanding near wood.

How can I reduce duct noise?

While nobody will be able to entirely get rid of the noises your HVAC system makes, there are several things you can do to reduce loud air duct noises. 


While it may cost some money, the most effective solution short of replacing your entire duct system is to clean, seal, and insulate the ductwork. This will reduce pressure differences and soften the effects of any expanding and contracting metal ducts. Contact your HVAC company about duct cleaning, sealing, and insulation solutions, such as acoustic duct liners, Aeroseal duct sealing, and fiberglass insulation. Always hire a professional for ductwork cleaning work. 


Dampers can either be open or closed. Check the dampers on the supply side of your ductwork and try opening them up one at a time to see if this reduces the popping and banging noises. You can also adjust the actuator inside of the duct dampers up or down to reduce the duct noises. If you don’t know how to do this, contact your local HVAC technician. 


A clogged airflow severely restricts airflow. By changing out your air filter you can help return proper airflow to the entire system. You should clean or replace your air filter every 30-60 days anyway for improved HVAC efficiency and better indoor air quality. 


Circular vents tend to make a lot less noise than rectangular vents. This is because the walls of rectangular vents can move in and out a lot easier. Circular vents have more support and thus are less likely to move and make noise. 


A dirty and inefficient HVAC system can cause unnecessary HVAC noise. Make sure you schedule furnace/heating maintenance every fall and air conditioning maintenance every spring. Sign up for a home maintenance plan so you never forget this important home maintenance task. 


You can get rid of noisy air ducts entirely by installing an HVAC system that doesn’t need them in the first place. Learn about ductless mini-split HVAC systems.

What is the purpose of an air duct?

An often overlooked, yet significant element in your home’s heating and cooling system is your ductwork. Without air ducts, there would be no point in having a heating or air conditioning unit.

Air ducts are responsible for distributing warmed or cooled air throughout your home, and for keeping you comfortable. Improperly designed or failing ductwork can cost you a great deal of money in energy loss and in some instances, lead to a premature failure of your heating and cooling units. 

I hear that your can leak. What does this mean?

Studies have shown that leaks in your ductwork are responsible for as much as 25% of the energy loss inside your home. Air ducts require a balance in pressure to evenly distribute heated or cooled air throughout your house. Gaps, dents, or loose seals can all allow air to escape into the attic. This imbalance of air pressure can make the job of your heater or air conditioner more difficult. Your unit has to work extra hard to make your home comfortable. Anytime your heating or cooling unit has to perform overtime, you are sacrificing comfort while wasting energy and money. 

How can I tell if my ducts are leaking?

While there are several ways to tell if your air ducts are leaking, a telltale sign is often your level of comfort. If you find that you’re always running your heating or cooling unit and your home never seems to reach a desired temperature, or some rooms are more comfortable than others, your ductwork might be to blame. Homeowners are usually quick to blame their air conditioner or furnace for their comfort concerns. In many instances, it’s not the unit to blame rather, the ductwork isn’t performing to it’s fullest potential. The best way to be certain is to contact a professional to help you accurately assess the condition and performance of your ductwork. 

If my ducts are leaking, how can they be fixed?

Contrary to popular belief, the best way to seal or repair your ductwork is not by using duct tape. Cement mastic not only seals your ducts, but also keeps contaminants out. When done by a trained professional, your properly sealed air ducts can reduce energy costs significantly. 

If my ducts are sealed, why do they also need to be insulated?

Even if you have a perfectly balanced system with no leaks, your air ducts can still lose energy. Imagine how sweltering hot the air inside your attic gets in the summertime. Now imagine how effective your bare sheet metal ductwork is if it passes through your attic without insulation. All the cold, conditioned air you are trying to cool your house with is being warmed as it passes through ducts that are not insulated. Some studies have shown that the same amount of energy lost via leaks can also be lost due to a lack of insulation.

Frequently asked questions on performance

What is HVAC energy efficiency?

In basic terms, energy efficiency means that the least amount of energy is used to produce the largest effect. A higher efficiency A/C unit will cool your house more while using less electricity, while a higher efficiency furnace will use less fuel to produce the same amount of heat. 

What is Coefficient of Performance?

The term Coefficient of Performance (or COP) is used as a measure of the amount of power consumed by a system when compared to the amount power output. COP is a standard metric of efficiency, with larger numbers signifying higher efficiency. COP values for a home heating or cooling unit tend to run from 2 to 4. When you’re shopping for a new system, look for those in the higher end of the range. 

What is Energy Efficiency Ratio (EER)?
The Energy Efficiency Ratio (or EER) of an A/C unit is the ratio of output cooling energy to the input electrical energy. Cooling energy is measured in British Thermal Units (BTUs), while electrical energy is measured in Watt-hours. EER is measured over a period of time in order to determine the operating efficiency of a given cooling system. While the EER rating will be displayed on the unit, a cooling system must be periodically evaluated to ensure it is still operating at its sticker EER value. Regular HVAC service is important in making sure your cooling system operates as efficiently as it is intended to.
What is Seasonal Energy Efficiency Ratio (SEER)?

The Seasonal Energy Efficiency Ratio (or SEER) of an HVAC system has a lot in common with the EER, being the ratio of output cooling energy (in BTUs) to the input energy (in Watt-hours). SEER goes beyond EER, by taking into account how a unit will function over a season as temperatures vary. You should look for a SEER rating of 15 or higher to ensure that your HVAC system will operate at full efficiency in all temperatures, winter or summer. Systems with higher SEER ratings tend to need less HVAC service and need to be replaced less frequently, while using less energy. 

Heating Seasonal Performance Factor?
The Heating Seasonal Performance Factor (HSPF) is a measure of the efficiency of a heating unit. It is similar to the SEER rating, but covers the heating efficiency of an HVAC system. A higher HSPF means that your system will use less energy to produce more heat.
Annualized Fuel Utilization Efficiency (AFUE)?
Furnaces are rated by the Annual Fuel Utilization Efficiency (AFUE) ratio, which is the percent of heat produced for every dollar of fuel consumed. Like the miles-per-gallon rating on your automobile, the higher the AFUE rating, the lower your fuel costs. 

How does multi-stage heating work?

If you have an old furnace, you might wonder what new furnaces have that could benefit your home’s energy efficiency. Multi-stage heating is an excellent example of an innovation that helps your HVAC system work more effectively.

Single-Stage Heating 

When you have a single-stage furnace, you have two options: on and off. Like a light switch, a single-stage furnace either provides full heating power or none at all. This is considered the least expensive and generally the least efficient of furnaces, simply because it is always running full-blast, if it is running at all. Single-stage furnaces can certainly be effective at heating a home even during the coldest winters. However, the inability to tweak the power usage during the milder temperatures of the day leads to lower overall efficiency. 

Two-Stage Furnaces 

Compared to single-stage furnaces, a furnace with two stages has the option to burn fuel to generate heat at a high or low setting. This allows the furnace to tailor the amount of energy used based on need. Furnaces with more than one stage are ideal for use with programmable thermostats, because then the system can use the benefit of time to gradually increase the heat in the home to the desired temperature. Using less power translates into lower fuel consumption for the same temperature settings, which often turns into decreased energy usage and lower utility bills. 

Variable Speed Blowers 

If you are thinking about buying a furnace with two or three stages, you should also consider the speed of the blower. The blower motor delivers the heated air to the ductwork and throughout your home. With a variable speed blower, your furnace