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Installing an air source heat pump

Last updated 5/27/2022

The installation process for air source heat pumps in your building will depend on the type of air source heat pump you're installing, whether your system will include mini splits or a central packaged system, and whether your system is ducted or ductless. We spoke with some homeowners who recently installed air source heat pumps in their homes to help compile the following details and tips about the process.

Before the installation: understanding your heating and cooling needs

It's good to speak with several and compare quotes before selecting the contractor for your air source heat pump installation. Once you decide on the contractor, heat pump equipment, and financing, you'll sign a contract and prepare for your heat pump installation.

Sizing and design of an efficient heat pump system

Before starting an air source heat pump installation, your contractor will usually visit your home to assess your heating and cooling needs. They'll also review the layout, existing equipment, ductwork, and any nuances about your home that would impact your heat pump system's design, setup, and configuration. They may have one to two site visits to your home to take measurements, develop the design, and ensure your heat pump system will meet your heating and cooling needs. Your air pump contractor may also perform a "Manual J" calculation, which gives them information about heating and cooling loads for your home.

What is a Manual J? It is the only procedure recognized by the American National Standards Institute (ANSI) and required by residential building codes. A Manual J is also frequently necessary for you to be eligible for any state and local incentives.

If you're looking at a ducted system, your contractor will also inspect any existing ductwork to ensure it's efficient and well-sealed. During the visit, contractors will also ask questions about your current heating and cooling systems and your heat pump project goals. For example, are you looking to only heat and cool a specific area or new addition to your home? Or do you want to cover as much living area as possible with air source heat pumps? Your answers will determine the air source heat pump system they recommend installing.

Financing your air source heat pump installation

If you're planning to finance your heat pumps, you may need to take additional steps before installation, especially if you're leveraging a state or local program to get a heat pump loan or rebate. Work closely with your contractor and lender to follow any guidelines. Some of the various state program websites are available here for reference:

You will likely need to allow some additional time to process your heat pump financing, especially if you leverage a state or local incentive for your purchase. Work with your contractor and lender to coordinate the steps. In most cases, you'll need to pay a deposit to initiate the installation to cover the hard costs associated with equipment and have your installer book time.


Preparing for your air source heat pump installation

There are a few things you'll want to make sure to confirm with your HVAC contractor or heat pump installer before your installation, including:

  • Confirm HOA rules: If you have a homeowners association (HOA), check your by-laws or find out from them if there are any rules or regulations for the placement of outdoor equipment outside or on the roof. You may need approval, and you'll want to confirm that ahead of time so as not to delay anything mid-installation.
  • Check to see what space you need for equipment: When the various equipment arrives at your home for your heat pump installation, you'll need somewhere to store it. You may be able to leverage a basement or storage space but may also need to rearrange some other rooms.
  • Verify your timeline: You'll want to confirm how many days the installation will take. While usually, they'll be doing work in specific areas, there will still be some disruption to your day-to-day life as there would be any significant work on your home. It's likely not as disruptive as a kitchen renovation, but it's more than getting a new refrigerator hooked up.
  • Be prepared for a bit of downtime: While the installation is in progress, you may have one day or night when you don't have heat or air conditioning. So, you may have a space heater or wall A/C unit that could come in handy.
  • Supply chain issues may impact your installation process: Like solar and other industries relying on manufacturing products and technology, there are some supply chain delays with heat pump equipment. Certain brands may be more available than others, so you can work with your contractor to learn about the different manufacturers of heat pumps and their specific products.
  • Just ask questions: If you don't understand why your installer suggests a particular piece of equipment goes in a specific location, ask your contractor. There are often multiple ways to make a heat pump system design work and if you prefer something other than what your heat pump contractor suggests, ask if your preference is possible. It may not always be or require more time and money to configure, but you usually have options.

Even the most prepared contractor and well-laid-out plan may have surprises once the contractor arrives at your home for the heat pump installation. You'll like want to be available to answer any last-minute questions that pop up during your installation.

6 steps of installing an air source heat pump

Ductless heat pump systems are easier and faster to install than ducted systems, with most taking between two to five days. Systems with multiple units or those that use ductwork will have a longer, more involved installation process. Whether ducted or ductless, most air source heat pump installations will follow these six basic steps:

  1. Getting equipment delivered and installing indoor units
  2. Creating access points inside of the home
  3. Connecting outside pipe to the indoor units
  4. Installing outdoor unit
  5. Connecting wiring & electricity
  6. Finishing touches and quality assurance/testing

Step 1: Equipment delivery and installation of indoor units

On the first day, the various equipment pieces will usually get delivered. Most air pump installers will start by setting up the indoor unit for your air source heat pump. If you've chosen to install a ductless system, the contractor will locate a free place on the wall inside the zone to place the unit. They will install a mounting plate to hold up the indoor unit and then secure the indoor unit to it.

If you've chosen a ducted system, your installer will also need access to your ductwork so that they can connect the indoor unit to the ductwork (whether in the attic, basement, or elsewhere). If you have existing ductwork that the contractors will use, they may also take this time to do any necessary repairs to maximize the efficiency of your new heat pump system. If you don't have existing ductwork in your home, installing ductwork to circulate the air will be one of the first steps they take.

Step 2: Create an access point in wall for connection

For your heat pump system to circulate air, you need an access point between the indoor unit or air handler and the outdoor condenser. Your installer will drill a hole in the wall to run piping and lines, providing an outlet for the refrigerant lines and electrical lines and a condensate drain line that will transport water from the indoor unit to the outside. The installer will use a hole saw on the exterior of your home and the room where the indoor unit is installed for a mini split system. In a ducted system, the access point will be near the indoor air handler (most often in an attic or basement).

Step 3: Connect the pipes to the indoor unit(s)

Next, your air source heat pump contractor will connect the refrigerant line and the condensate line to the indoor units. The refrigerant lines allow refrigerant to cycle through the indoor and outdoor condensers. Depending on whether your air source heat pumps are heating or cooling, the lines will transport warm or cool liquid to the indoor units, forcing it as air into the zone.

Step 4: Install outdoor unit

Once the indoor setup is complete, your contractor will install the outdoor unit. Installers will typically put a concrete slab on the ground to hold the outdoor condenser for larger packaged or central systems. If yours is a mini split system or a smaller air source heat pump system, they will often mount it to the side of your home. This mount will typically be lifted above the ground, especially in colder areas where your installer will ideally mount the system above possible snow lines.

Either during this step or the next one, your contractor may bring in an electrician to help with ensuring the electrical components are working correctly within the overall heat pump system.

Step 5: Connect wiring and electricity

After installing the indoor and outdoor units, your heat pump contractor will connect them through the refrigerant line and electrical wires. Installers will insulate the lines or run them through conduits on the side of your home to protect the wiring from the elements. They will also install a drain line outside your home to bring condensation from the unit out.

Step 6: Finishing touches

A few finishing touches will complete the installation process. One is to affix the pipes to the sides of your home, so they're secure. Another is to install sensors, as many air source heat pumps will come with sensor technology to communicate the temperature in different zones to your thermostat. Many air source heat pumps also come with wireless remotes to adjust the temperature and enable monitoring or adjustments via an internet connection on your computer, tablet, or phone.

Your contractor will also ensure patches to drywall and painting are complete, finishing the look. If necessary, some heat pump contractors handle the removal of your old system, like a furnace. You'll want to confirm if the disposal is included in your installation (and the quote) with them.


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