Heat Pump Installation Process
December 1, 2025
In recent decades, heat pumps have been gaining momentum as comprehensive heating and cooling solutions for modern American homes. However, these systems are complex. When installing a new system for your home, it’s not as simple as installing a standard HVAC component.
Given the intricacy of these systems, it’s always best practice to work with professionals for the installation. However, HVAC teams may not always apply the correct steps, leading to malfunctioning units or shorter lifespans. New AC Unit shares the complete installation process so you, the homeowner, will be aware of the step-by-step procedure and can determine whether your installer is doing it right. Keep reading to learn more!
The Complexity of Pump Installation
Heat pumps are dual-function systems that require precise technical integration and system matching for optimized performance year-round. Plus, they are powered entirely by electricity. No natural gas is used to create heat, unlike more conventional HVAC systems. Because of these factors, pump installation is complex.
For many HVAC teams accustomed to traditional units like the Trane 3 ton, pumps are a completely new configuration. It’s more likely for them to install pumps with the wrong size or disorganized wiring.
You can avoid this issue, even without the technical know-how, if you know how the installation process works. With the resource we shared, you’ll gain peace of mind knowing that your investment is installed as intended. Note that this is not a DIY guide. Heat pump installation must always be done by experienced professionals.
Typical Length of an Installation
How long is the entire installation? On average, it takes eight hours from start to finish. Any shorter, and this could be a red flag. However, factors such as weather, air duct alterations, or unforeseen electrical challenges can lengthen or shorten installation time. What happens during the eight hours? Here’s a detailed explanation.
1. Assessing Your Heating Needs
The installation process begins well before the HVAC team arrives at your doorstep. Before anything else, the most important thing is to determine whether the pump system you’re buying will meet your needs. In HVAC terms, the pump must have the right “size” or capacity to adequately heat or cool your interiors.
How do you know your home’s HVAC needs? A Manual J load calculation is the most accurate way to measure and determine the best-sized equipment for your needs. There are various factors to this calculation, and it’s not just the square footage of your interiors.
- Quality and thickness of insulation
- Number and size of windows and doors
- Number of regular occupants
- Total square footage or area of the space
- Square footage of floor over crawl space
- Square footage of the floor over the basement
- Number of rooms without ducts that need heating
- Ceiling height
- And various other factors
In other words, there’s a complex calculation needed that a sales representative can’t do in a single sitting. If they try to sell you a pump system and claim that your home needs a specific British thermal units (BTUs) to heat or cool your property, then they’re most likely trying to make a sale. Assessing your heating needs takes longer, and a visit by an HVAC expert is necessary to make an accurate calculation.
2. Setting Expectations During Installation Day
After working with an HVAC expert, you’ll schedule the installation day. It’s finally here, so what should you do? Given how the process can take all morning and afternoon, it’s best to prepare yourself and your home for the job.
Your installation team should send a message about their arrival, along with images of the team members arriving at your home. Clear, consistent communication is key to your safety and comfort, especially since you’re letting strangers into your home.
Once they’re finally at your doorstep, the lead installer should share and review the project details with you. Review the equipment information and confirm it matches the model you ordered. Make sure additional accessories are available, and clarify whether they’re aware of any special instructions you’ve provided, especially regarding the layout or features of your property. Once everything is ironed out, the team should begin the process, laying down floor protection and setting up their equipment.
3. Complying With Refrigerant Removal Standards
If you have an old pump that needs to be removed first, this step is necessary. The EPA sets strict standards regarding the proper removal of appliances with refrigerants, helping avoid their leak into the atmosphere. If you’re replacing an old pump, the installers must have a recovery machine and a recovery tank to safely and legally remove the refrigerant.
After recovering the refrigerant, the next step is to remove the electrical wiring and disconnect the old unit. The old heat pump will have two main power components: the whip and the disconnect box. A reliable installer must replace both electrical safety systems, especially since they are exposed to the elements. Plus, they may be older units that cannot keep up with the demands of newer heat pump systems.
When your installer replaces the whip and disconnect box, they ensure the electrical infrastructure is safe and correctly sized. Only after can the existing outdoor heat pump unit be actually removed from the location.
4. Area Preparation
Heat pumps come in two parts: the outdoor and indoor units. More often than not, the site where the outdoor component will stand must be prepared before installing the new unit. This step is necessary to ensure that the pad is level, stable, and elevated.
- Pad Replacement and Ground Prep: The existing pad must be replaced, and the ground leveled. A gravel base is the gold standard for ensuring a uniform surface throughout.
- Pad Material: In areas like AZ and TX, a composite pad material is ideal. It can withstand the fluctuating temperatures.
- Elevation Requirements: The heat pump needs to be elevated by about 3 inches to help protect against standing water, moisture, and ground debris. However, in practice, some installers can raise the unit by up to 6 inches. In Phoenix, Houston or Dallas and TX areas that receive regular snowfall, the elevation can reach 18 inches for snow clearance.
5. Uninstalling the Indoor Evaporator Coil
The other half of the heat pump system is the indoor evaporator coil, which you’ll find above the furnace and connected to the outdoor unit by refrigerant lines. If you have an old unit, the process will involve removing the old coil before the installers can fix the new one on units like the Trane 3.5 ton.
Removing the Existing Coil
- The installers first locate the coil location. The unit usually sits inside a sheet metal plenum, where the refrigerant ends.
- To access the coil, the metal plenum must be disconnected first. This step might get complicated if access to the area is restricted.
- The existing refrigerant line set is then removed.
- Once the old coil is free from the lines and ductwork, the technician can slide it out of the location.
Installing the New Coil
There are two options for new evaporator coils: cased and uncased. Here’s what you need to know.
Cased
- Cased coils are pre-installed in an insulated cabinet.
- The installer needs to let it sit directly on top of the furnace. Modifications are rarely required.
- The technician only needs to connect and seal it to the existing sheet metal plenum. This ease of installation makes it the preferred option.
Uncased
- An uncased coil doesn’t have an insulated cabinet.
- There are more installation requirements, resulting in longer prep time.
- When installed properly, this variation will provide the same comfort and efficiency as a cased coil.
6. Removing Line Sets and Additional Wires
After the outdoor and indoor components are removed, the next step is to take off the existing wires connecting both units. There are various lines and wires your technician will need to handle. First is the refrigerant line, which is a set of two copper lines. These tubes are where the refrigerant flows through to reach the outdoor condenser and back to the internal evaporator coil.
- Suction Line: The bigger line that returns the refrigerant to the condenser
- Liquid Line: The smaller line that brings the refrigerant back to the evaporator coil
Together, these two lines create the loop that allows the whole system to continuously heat or cool an indoor space.
Aside from the refrigerant lines, your technician will also remove the control wire. It’s another line that runs from the furnace along the line set to the condenser. This wire transmits the low-voltage signal from the thermostat (via the furnace) to the heat pump, indicating when it should turn on or off for heating or cooling.
The pump also requires knowledge of outdoor temperature to operate effectively. This feature is necessary because the system uses a reversing valve to switch modes. With an outdoor sensor, the pump can gain temperature data. Plus, it will know when to activate the auxiliary heating (using heat strips).
Brazing is the final and most critical step for this phase. This is when the technician permanently connects the new line set to the pump’s service valves. Your installer will use two gases and a filler rod, then heat the components to 1,200°F to let the rod melt and flow into the joint. This process creates a tight, leak-free connection that maintains system integrity. Like we said: not ideal for DIY!
7. Installing New Wiring
Once the new refrigerant lines, the outdoor condenser, and the internal evaporator coil are all set in place, the next step is to install and connect the new wiring. There are two sets: high-voltage and low-voltage wiring.
High-Voltage Wiring
The high-voltage set powers the entire pump system. Your technician will mount a new disconnect box to the exterior of your house, near the outdoor unit. The box will need to connect to your existing power supply. Once installed, the disconnect box will serve as the safety shut-off for the outdoor unit.
Low-Voltage Wiring
Meanwhile, the low-voltage wiring provides power for the communication between the outdoor and indoor units. The wire runs from the thermostat to the control board inside the furnace, continuing out to the heat pump condenser at designated terminals. The wire transmits the signals when the thermostat calls for heating or cooling, allowing the heat pump system to cycle based on the set temperature and humidity in your home.
After installing the high- and low-voltage wiring, your installer must program the thermostat and control board to manage the system’s operational boundaries. In particular, they will set parameters to determine when the heat pump must stop operating, and backup heat strips will take over. Plus, this step allows the installer to determine the temperatures at which the system initiates defrost mode. Otherwise, the pump will continue to run even if it freezes.
8. The Commissioning Stage
Connecting the wiring is the last step of the actual installation process. The next step is to test the newly installed system and determine whether anything needs to be addressed. This phase is called the commissioning stage. As the homeowner, you should expect the following.
- The technicians must turn on the entire system and run it for 15 to 20 minutes.
- The next step is commissioning the pump, during which the technician tests the heating, cooling, and defrosting mechanisms. This step should last for 45 minutes to two hours.
- A knowledgeable technician will also evaluate thermostat operation, system sequence of operation, and various other functions. They should be able to communicate with you about how well the system is working and if there are any additional things you’ll need to know.
The commissioning stage does require additional time and labor, but it’s necessary for your peace of mind. A reliable installation team must take the time to show you that the heat pump is working as it should and not rush to leave your property.
9. Closing and Cleanup
Once the commissioning stage is over, the crew will begin the cleanup. Tools, equipment, and old components must be loaded and removed from the premises. Lastly, the floor protection must ensure that debris doesn’t scatter around your home. If needed, the team must sweep and clean up any material, leaving your spaces as clean as they found them.
As part of the closing process, your technician must provide a walkthrough of the new system and go over matters like safety, maintenance, and warranty. Most importantly, they should teach you how to toggle your thermostat between heat and emergency heat, especially when temperatures fall below 35°F. Owner education is critical at this stage to ensure proper functioning and longevity of the system.
Work With Trusted HVAC and Heat Pump Experts
Heat pumps are a significant investment, and the installation process can be intricate, with plenty of room for error. Looking for a team you can trust? New AC Unit is an established AZ and TX company with years of experience in the HVAC industry. We omit the middleman and work directly with manufacturers to reduce prices. Then, we assign an experienced and licensed technician to complete the installation of the new system at your own schedule.
Ready to enjoy the benefits of heat pump systems without the hassles of incorrect installations? Contact us today to get started!