What to expect during a Premier HVAC system Installation Process

We aren’t going to lie, the installation process for a new HVAC system is complicated. When customers ask me what’s involved in the process, they’re often shocked to learn how much goes into it.

It’s easy to cut corners so that a HVAC system runs “good enough.” But “good enough” often means losing thousands of dollars in energy costs over the life of your system, decreased comfort for you and your family, and frequency in breakdowns and repairs. This is unacceptable.

In this article, we are going to cover our entire air conditioner installation process in detail, from start to finish! If you’re committed to getting the most from your HVAC system, read on. By the end, you’ll have the peace of mind that comes with understanding each step.

There’s a large amount of work that goes into each and every HVAC system installation we complete—and this work contributes to not only your comfort and the efficiency of your system, but also your safety! This is particularly true if it’s a gas-powered system in question.

This is NOT a DIY guide. HVAC system installation should always be handled by a licensed professional. Once you read each step involved, it should be easy to see why.

*this process covers a change out of a conventional split system. The process might vary a little depending on your particular situation and equipment being installed.

Planning the Replacement or New Installation of Your Central Air Conditioner

Most existing HVAC systems that are replaced today are between the ages of eight to 30 years old.

Modern air conditioners are 20-50% larger in height, length, and width. This allows for a larger coil which, in turn, makes the air conditioner more efficient. Because of the larger size of modern air conditioners, the current location of your existing air conditioner may not accommodate the new one. Sometimes the air conditioner must be relocated, particularly if there are state or manufacturer regulations on space clearances surrounding your unit. Others require that unit to be within a certain distance to the utility meter. In some cases, this creates additional costs.

This is the first consideration for a homeowner, because it may require moving equipment or modifying your home’s ductwork.

Collecting A/C Information During the Home Consultation

During your initial in-home visit, the advisor has the responsibility of reviewing the existing air conditioning system. Important information such as a proper load calculation needs to be collected so they can provide you an accurate proposal. This information is then passed to the installation team. The advisor will also go over equipment options and add-ons that are tailor fit to your needs as well as explain finance options.

Depending on the job, specialized equipment may be needed, which the installation team can bring with them because of this step.

Having the proper information before the day of installation increases the chances of the job being completed successfully and promptly.

We will schedule the installation date during this process on whatever day works best for you.


At Premier Heating and Cooling, we believe in doing things right the first time – and that means pulling permits. Your city, municipality and/or subdivision may have different restrictions and requirements. But regardless of your location, an HVAC installation requires a permit.

Alterations that require permits are typically more permanent. For example, you need a permit to install or remove a furnace or air conditioner. But you don’t need a permit for a new stove if you don’t have to move gas lines.

Permits are required by law. Before work can begin, contractors must obtain, or “pull,” a permit.

This ensures that the job will be inspected by a third-party inspector, a city building inspector checks that the installation follows local and state building codes as well as manufacturer specifications. Your permit fees cover the cost of an inspection. These fees can be anywhere from $75 – $500

Pulling permits adds cost to the job, but knowing the job was done right and safely provides peace of mind to our clients and protects their investment.

The Arrival of the Install Team, Review, and Safety

Before your highly qualified, NATE Certified installation team arrives, you should receive a call or text letting you know they’re on their way.

We will also send pictures accompanied by bios of the installation team that will be working at your home ahead of time. This is an additional safety and comfort factor before a stranger enters your home. Premier Heating and Cooling performs extensive criminal background and drug screens of every employee.

Once they arrive, the lead installer will share and review the job information with you. This is often included in a packet that includes details of the job. This packet contains the equipment information, accessories to be installed, and any special instructions given by you to the advisor.

It’s important to allow a few moments for this review. This will prevent costly and aggravating mistakes from happening during the installation. Communication is a key component to a successful installation.

While you are reviewing the job details with the lead installer, the other member(s) on the team will use this time to start laying down floor protection and getting tools and equipment in place. They will also start a safety process that includes turning off electrical circuits and gas supply to the existing HVAC equipment.

Removing Your Existing Central HVAC unit

Your existing air conditioner contains a refrigerant that needs to be removed before a new one can be installed. According to the EPA standards, it is unlawful to openly vent this refrigerant into the atmosphere.

A device known as a recovery machine must be used along with a recovery tank to safely and legally remove the refrigerant in the existing central air conditioner system. This is the only process that allows for the safe removal and proper handling of the refrigerant.

Any individual handling any refrigerant or equipment containing refrigerant must have an individual EPA certification. An EPA certification only certifies the name listed on the certification. Therefore, each member of the installation team, service team, or anyone who might handle refrigerant or equipment containing refrigerant are required by law to have their own individual EPA certification.

Once the refrigerant is recovered properly, electrical wiring is disconnected, and refrigerant lines are disconnected, the condenser is ready to be removed.

The indoor evaporator coil is the other half of your air-conditioning system that sits above (next to, or below) the furnace. The sheet metal plenum must be disconnected before the new coil and/or furnace can be installed. This process can be complicated when access to the coil is restricted. The most common restrictions are rooms built around the system such as closets or finished basements. This prevents access to all sides of the coil or plenum. An additional charge may be added to the cost of the job based on difficulty.

Additional prep work to the supply plenum may be required before the new coil can be installed

If your replacing the furnace also, which is highly recommended to do during this process because of how labor intensive the project would be after the fact, you would begin disconnecting the high and low voltages from the furnace, return ductwork, flue pipe, gas line and anything else mounted onto the furnace. In some cases the furnace will need to be dismantled into smaller sections to allow the proper clearance to be removed off site.

Next, the existing refrigerant line set can be removed. This is a set of two copper lines through which the refrigerant travels from the outdoor condenser, then back into the indoor evaporator coil.

Sometimes the line set is concealed by a ceiling or in a wall, or it is buried underground or in concrete. Sometimes providing access is not an option or possible. In these cases, you have the option of finding a new location to run a new line set or reusing the existing line set remains. If the existing line set must be reused, it must be flushed and cleaned properly, then pressure tested. It is never recommended to keep an existing line set if it can be replaced.

Preparing the Area for the New Central Air Conditioner

Now that all the old equipment is out of the way it’s time to prep the outdoor and indoor areas for installation.

In most cases, the existing location of the air conditioner will require some prep work before the new air conditioner can be set in place. This prep work includes replacing the pad that the new air conditioner will set on. Before the new pad can be set, the ground must be leveled. Good HVAC companies use a gravel base to level out or build up the area where the new air conditioner will be placed on top of a composite pad. Composite pads are purposely designed to be outside and last the lifetime of the new air conditioner. Additionally, it’s often better equipped than concrete to absorb vibrations from the machine, which can reduce noise and shaking.

Now, the secondary drain pan, which incase of flooding would shut the system down using a wet switch, should be set and level. This is done at the indoor unit and is highly recommended and even code in some municipalities. This could potentially save you thousands in water damage if your A/C drain ever backed up and leaked into the home. 

It is now time to install your new central HVAC system per local building code and manufacture specifications.

Installation of new central HVAC system

New line set
The new refrigerant line set is a combination of two individual copper lines. One line is always bigger than the other and is insulated. The bigger line is called the suction line, and the little one is called the liquid line. 

The key is installing the line with as few bends and turns as possible. When these bends are necessary, the soft copper can be bent by hand or a tubing bender. It’s common to install the line set as close to your home’s beams and ductwork as possible. It’s also recommended that you secure the line every 4-6 feet. Plastic or copper strapping is common. If you don’t properly protect the line, it can corrode. Galvanic corrosion (also called bimetallic corrosion) is the breakdown of metal when two dissimilar metals come into contact,  if allowed to occur, it could eventually reduce the integrity of the copper refrigerant line over time until it causes a leak.

There is a hole drilled through the band board of the house to the outside, near the air conditioner. The hole size will be between 2-2.5” in diameter, depending on the type of line set being used. Enough of the line is pushed out to reach the service valve of the air conditioner. Eventually, the installer will connect this line to the air conditioner itself.

Setting the new outdoor unit (condenser)
So far, we’ve set the pad, leveled it, and our refrigeration lines and electrical disconnect are ready to be wired into the new air conditioner condenser. Uncrating the new air conditioner and setting it on the pad is step one. After uncrating the unit, a good installer will inspect for any damage. Sometimes panels or coils will get damaged in transit. Any damage should be reported to you immediately.

Premier Heating and Cooling runs multiple inspections on equipment, both when it arrives and when it’s installed, to ensure it is in working order.

If there is a dent, that doesn’t necessarily mean there is any damage that will affect performance. However, you always have the right as a customer to not accept the damaged unit and ask for another one.

The line set that was installed in the previous step is then formed and fitted to the appropriate service valve on the new air conditioner. After the line set is fitted to the service valves, they must be brazed in. Brazing, a form of welding, is a process using two gases (oxygen and acetylene) and a filler rod made of an alloy metal and silver to join the copper line set and service valves. The valves are heated to a minimum of 1200 degrees Fahrenheit or until the filler rod will flow to weld the connection.

If this process is completed properly, the copper line set, the filler rod, and the service valve are all melted together for a tight, leak-free connection.

Indoor coil and/or furnace
Dependent on your situation. The next step is to install the new furnace on the secondary drain pan that was previously leveled.  Our technicians will connect the system to the components needed for its operation.

This includes your ventilation system, or, your ductwork. Ductwork must be hooked up to the furnace correctly in order to avoid damaging them. Air ducts often have to be adjusted and shifted during this process, and this is where mistakes can happen if not handled carefully.

Next, our techs hook your furnace up to its power source. We have your safety to contend with when it comes to gas-powered furnaces. Any connections to your gas line require an experienced and specially licensed professional to manage and ensure proper installation.

Now comes the line set and filter dryer installation. Filter driers are a key component in the refrigerant system. They serve two main functions. The most important function of a filter drier is to absorb moisture. The second is to provide physical filtration. Most new air conditioner condensers come with a liquid line filter drier for you to install. Any time a refrigerant line is open to the atmosphere, it is vital to install a new filter drier. This is true of installations as well as service repairs.

Manufacturers recommend the filter drier be installed close to the expansion valve (TXV) at the indoor coil, as often as possible. This keeps the TXV protected and keeps the filter drier from being exposed to weather where it could rust.

This brazing process is the same for connection to the indoor evaporator coil. This, again, involves open flames and should only be performed by a trained professional. The gases used in the process are explosive. There is an open flame outside and inside the home. It can be dangerous to the installer, the homeowner, and the home, causing permanent damage without proper training. Following manufacturer and safety guidelines is key. All good HVAC companies have strict processes in place for their install teams to prevent failure as much as possible and have all the tools needed to install a system professionally and thoroughly.

Both service valves and  metering devices called an expansion valve that will be damaged if not protected from the heat during brazing. If these get too hot, or any contaminants are introduced, they will be compromised and fail to operate.

The HVAC industry requires brazing with nitrogen every time to prevent this damage. A tank containing dry gas called nitrogen is hooked up to a regulator and possibly a manifold gauge set. This allows the nitrogen to be purged while brazing. The nitrogen protects the inside of the copper tubing from oxidizing during brazing. The damage will not always be present immediately. Brazing with nitrogen, when done properly, will give the system maximum opportunity for performance, reliability, and dependability. After the system is brazed in both the indoor and the outdoor components, the system must be checked for leaks.

Leak check
After the system is brazed in, it must be checked for leaks using the same dry nitrogen used to braze, up to a specific amount of pressure. Using the dry nitrogen to pressure test the system achieves three things:

• It’s a preliminary leak test.

• The dry nitrogen will pick up moisture.

• It will also purge some contaminants out of the system upon its release.

It is very important to verify with the installation manual provided by the manufacturer what they recommend for pressure. Most systems are designed for 150 PSI when testing.If the preliminary leak test with nitrogen holds for a minimum of 10 minutes, then it’s time to move on to the next crucial step: vacuuming the system.

Vacuum and holding test
Typically a system is vacuumed to a minimum of 500 microns. The manufacturer’s recommended vacuum is found in the installation manual. Refrigeration systems are designed to operate with only oil and refrigerant flowing through them.

Our atmosphere is made up of oxygen, nitrogen, and moisture. These are enemies to the system’s operation and may enter the system during installation or servicing. Removal of these, along with air or other non-condensable products, is required. This is achieved through the vacuum process when installing the air conditioner. The vacuum process can take no less than 30 minutes and up to an hour or more depending on the size of equipment coils and length of line set.

Failure to provide a dry, moisture-free atmosphere before introducing the refrigerant into the rest of the system will in all cases promote an inconsistent operation, and eventually permanent failure of the system.

To achieve a successful vacuum on an air conditioning system there are several key tools and equipment that must be used:

• A reliable vacuum pump

• A micron gauge

• Manifold and hoses

• Vacuum rated core removal tool

The vacuum must achieve 500 microns or less in the system and hold the vacuum for this to be successful. This is also the second and final leak test. If a system does not hold a vacuum, then there is a leak somewhere.

Once a proper vacuum is achieved and has proven to hold, the system is ready to have refrigerant introduced to it. Refrigerant is the only product that can “break” the vacuum.

With the hoses still connected to the service valves of the air conditioner, the refrigerant is released into the system, breaking the vacuum by opening the suction-side service valve first followed by the liquid side second.

New High- and Low-Voltage Wiring
Good HVAC companies replace the disconnect and the whip when replacing a HVAC system, to ensure system safety. In cases where an old system lacks a disconnect box, a new one is required by safety codes to be installed with the new air conditioner. There are specific installation guidelines for sizing and wiring the disconnect properly. The service disconnect is required by state and local code requirements. All the electrical connections should be made according to the NEC (National Electrical Code).

The low and high voltage wire is connected directly into the condenser and furnace at the proper locations according to the installation instructions.

Condensate drain line
The moisture removed from the home during the cooling process travels down a plastic PVC pipe. It must be connected to the primary side of the evaporator coil. The evaporator coil has a primary and a secondary drain location. The primary condensate drain line will travel from the indoor evaporator coil to an appropriate floor drain or condensation pump.

A condensation pump is used where a proper floor drain does not exist in the home. There are also other reasons where a condensate pump is required or is beneficial to install. The important thing to remember if a condensate pump is used is that it must be serviced a minimum of twice a year to maintain proper performance.

Any condensate tubing or piping should be secured and glued with the proper cement. A trap and an overflow safety switch must also be installed in the condensate system. This is to protect the equipment and the area from flooding due to a restriction. The safety overflow switch is connected to the secondary port on the indoor evaporator coil and wired into the furnace control to shut down the system when it is tripped.

Filtration and add-ons
Filtration is not only important the longevity of system components, its vital to our health and quality of life. A properly designed HVAC system should be able to run an allergy filter without a problem.  Unfortunately, many systems have been installed and are being installed that have inadequate return air. At the very minimum we recommend a high surface area ( low resistance to airflow ), high MERV rating, 4″ pleated air filter,
This improves indoor air quality without an impact on the air flow of an HVAC system. 4-inch filters have larger pleats. That means they have more surface area to catch particles, making them last 3–5 times longer than 1-inch filters. A thinner 1-inch filter with a high MERV rating would clog very quickly (compared to a 4-inch pleated filter) since there is less surface area available to trap contaminants. Most HVAC technicians recommend changing 1-inch air filters every 30 days, while 4-inch filters can be changed every 3–6 months. Some 4-inch filters can even last up to a year.

If your system calls for a 1-inch filter, you’ll need a professional to alter your duct system to accommodate a 4-inch filter. This process may require additional time and labor discussed previously during the consultation.

Minimum Efficiency Reporting Value (MERV).  The MERV system is a useful tool in selecting filters to improve indoor air quality. 

Going with a 4-inch filter would mean you’d get a filter with at least a MERV 8 rating, which would remove contaminants down to 3 microns (a unit of measurement), including dust mites and some types of pollen. (For context, a human hair is 50 microns.) But if you have allergy or asthma sufferers in your home, you might want to go with a MERV 13. A MERV 13 filter will effectively remove allergenic contaminants down to .3 microns, like:

• Pet dander

• Bacteria

• Tobacco smoke

• Dust

• Pollen

Improving indoor air quality through filtration is not as simple as a purchase of a high efficiency allergen filter at the home improvement store.  It takes some analysis to select the right filter for each application. 

You can take it a step further and go with a HEPA bypass that continuously filters a portion of your homes return air. HEPA filters are the gold standard for filtration because they remove not only inorganic dust, but microorganisms such as mold spores, bacteria, pollen, dust mites, odor, microscopic allergens and many viruses.

Find out more about add-ons we offer here.

Start up and commissioning process

The startup and commissioning (testing) process is done after the system is completely installed and ready to operate. The system is turned on and must run for 15-20 minutes. This will allow the refrigerant to flow through the system and start the air conditioning process.

Upon initial startup of the new air conditioning system, the house should be very warm or have a “load” with a warm enough temperature inside the home to allow for the minimum potential to charge the system accurately. A temperature above 75 degrees Fahrenheit is recommended in most cases. This allows the components in the air conditioning system to be in full operation to allow maximum cooling potential during charging.

A good installer will check the thermostat operation, system sequence of operation, and multiple other areas. While the system is operating, the following data is important to collect to ensure proper operation within manufacturers’ specifications:

• Suction and liquid line pressure

• Suction and liquid line temperature

• Superheat

• Sub cooling

• Outdoor ambient dry bulb temperature

• Indoor ambient dry bulb temperature

• Indoor wet bulb temperature

• Return air temperature

• Supply air temperature

• Static pressure from return side, supply-side, and total static readings

• Temperature drop calculated

• High voltage current reading

• Amperage on the blower motor, outdoor fan motor, and compressor

• Low voltage current reading

• Line set length

• Amount of refrigerant, if any, added to the system

• Distance above or below the outdoor unit is in relation to the indoor coil

• Blower speed tap/CFM recorded

This is the basic list of the proper data that should be known and recorded. This is the only way to know for sure how the system is operating and if it is within manufacturing specifications. If any of these do not fall within manufacturer specifications, your system may not be warrantied by the manufacturer.

Commissioning is important for several reasons. For you, the peace of mind that you are receiving a properly set up and adjusted system for maximum comfort, efficiency, and dependability. It also ensures the manufacturer’s warranty will be in full effect. The benefit to the company installing the system is that it gives a baseline of operational performance in case any issues arise later.

It also gives the installing team confidence that before they leave, your system is in perfect operation. It is very common for systems to be installed and started up without much consideration for proper commissioning.

Proper commissioning is a specific process that requires training and special equipment to perform the process correctly. It also requires additional time and labor. Commissioning is the only way to know for sure exactly how well your system is operating.

A good HVAC contractor will have trained installation teams that will properly commission your air conditioner before they leave the job.

Clean up and Closing Process

The cleanup process is comparatively simple. All material and old equipment should be loaded up and taken away from the home. The floor protection should be rolled up last, keeping all debris from the installation inside the drop cloth and out of your home.

All areas should be swept and free of any materials or debris. You should expect to see the area in the same condition in which it was found.

A walkthrough of what was done during the installation should be completed with you. Going over safety, maintenance, warranty, and all special instructions are expected.

A visual inspection of the work completed should also be offered. Finally, we also take the time to go over warranties and guarantees. After the final walkthrough, final signatures and payments are collected.

How long did all this take?
Generally, for a full system, we would be at your home all day (normally 8:00AM – 6:00PM) , but can vary depending on your particular situation and equipment.


Now that the job is complete, an inspector will  check that the installation aligns with the manufacturer’s specifications as well as local and state building codes. We work with you past the completion of the installation and will help out with coordinating the inspection. We do not need to be in the home for this process. As long as the inspector passes the job, your all set to sit back and enjoy your new home comfort system.

We recommend that our customers get the installation inspected as soon as they can. We want to make sure everything’s right. Even knowledgeable, licensed contractors can miss things every now and then. If we did, we would quickly make any corrections required, and get the inspection process completed at no extra cost to you.

Did you know your equipment comes with a limited Manufacturer’s Warranty?

Most manufacturer’s of HVAC equipment, require any new equipment to be registered in order to receive the full, limited warranty. Whether you have a brand new heat pump, central air system or a new motor installed, the part needs to be registered with the manufacturer.  This ensures that any licensed HVAC contractor can perform warranty service if that part goes out. For new homes, the limited warranty date starts at closing. These limited warranties can be filed and looked up online.

It pays to make sure the limited warranty for equipment is filed in a timely manner. Premier Heating and Cooling always files warranties online on-site as part of our regular service to ensure it is done correctly and on time. We take care of all the paperwork for you.

Find the Best HVAC Company For You

Are you looking for a good HVAC company to install your new air conditioner system? We hope this article has given you some tools to assist in selecting one that meets your needs.

At Premier Heating and Cooling, we take pride in our installation process and hold our technicians to high standards to ensure the performance of your system. We believe in doing it right the first time.

Are you in the Worcester area and ready to take the next step with one of our experienced professionals? Contact us today to schedule a no obligation consultation. We’d love to be the ones to help install your next home comfort system!