There are plenty of reasons to install your own:
- Depending on the complexity of the job, you’ll save anywhere from $500 to $750 versus having an installer do the work.
- The tools and materials you’ll need can all be found at your local hardware store. No special tools or license is required.
- You can do it on your own time. After gathering your permit and materials, you’ll need about half a day, or 4–5 hours, including draining and filling the tank.
- This guide will walk you through every step of the process, with visual guidance and tips from the pros.
- And don’t worry; if you get stuck and need assistance, there are plenty of installers nearby that can help!
This guide will walk you through each step of replacing an electric tank water heater with a heat pump water heater. Make sure your current water heater is electric and verify that you have a 30 amp circuit breaker and at least 10-gauge wire.
Before you begin, read through this guide and your heat pump water heater’s installation manual. This will give you a sense of what you need and the type of work that will be involved.
Find an installation manual:
Get Your Permit
Most city codes or ordinances allow homeowners to install their own water heaters provided they have obtained a permit and submit to a post-installation safety inspection. Check with your city or county for permit requirements before you begin the installation process.
Where to Install Your Water Heater
In the Northwest, heat pump water heaters work well in most semi-conditioned, unconditioned spaces like garages and basements. If your existing electric water heater is in one of these areas, replacing it should be relatively easy — you’ll just want to be sure of a couple of things:
- The air temperature around the water heater shouldn’t drop below freezing. Generally, heat pump heaters will deliver hot water most efficiently in temperatures above 37 °F. Check your unit’s product specifications for more information about operation in low temperatures.
- You’ll need some space. Your new heat pump water heater will most likely be taller than the unit you’re replacing and, unlike conventional electric water heaters, it will require at least 750 cubic feet (about 8.5’ x 9’ x 10’) of surrounding air space to operate effectively.
Measure for the location for your new water heater and check the installation manual for all requirements. Check that you will be able to get the heat pump heater to the installation area and make sure to have the heater on-site before you start disassembly.
If you want to install your heat pump water heater in a tight space or in a living area, we recommend working with a contractor who can advise about the possible need for ducting, noise mitigation, and louvered doors (you may need to replace or put vents in your door).
What You'll Need
- Pipe cutter or hacksaw
- Measuring tape
- Plumbers pipe wrench
- Electrical current tester or voltmeter
- Socket wrench
- Crescent wrench
- Garden hose to drain existing tank
- Hand truck
- Electrical tape
- Wire nuts
- Teflon thread tape
- Water supply pipes
- Push-to-fit connectors do not require soldering; verify compliance with local code
- In Oregon, you may use up to 96” of approved flexible water lines to run from the supply line to the hybrid water heater’s inlet and outlet
- Pipe and fittings for temperature/pressure relief valve
- Shutoff valve
- PVC pipe and accessories for condensate lines
- PVC connectors, threaded for condensate outlet connection (both 45˚ and 90˚ elbows)
- Pipe hangers
- PVC glue
- Pipe insulation
- Earthquake straps (recommended if not required by local code)
- Condensate pump (optional)
- Clear vinyl tubing, sized for condensate pump and of sufficient length to reach drain or clear vinyl tubing and fittings to tie into existing condensate line (optional)
- Tubing hangers (optional)
- Drain pan to sit beneath unit (new unit may have a larger circumference than the existing tank, optional)
- Thermal expansion tank (required for closed plumbing systems and/or local code)
- Stand (if required by local code)
- Strut channel or wood blocking (for wall clearance if required by manufacturer; check installation instructions)
- Foam insulation pad (you can make your own out of 1.5” rigid foam)
- Foam pipe insulation sleeves
- Rags or old towels to wipe up any water spills
1. Remove Your Existing Heater
Measure the temperature of the hot water from your current water heater by running the sink or shower for into a bucket 3 minutes and taking the temperature with a low temperature cooking thermometer. You’ll want to use this as the setpoint for your heat pump water heater.
Start by turning off the power to the existing water heater at the breaker box. Double-check by removing the water heater’s junction box cover plate and holding a voltage meter next to the wire connections. If it does not light up, the circuit has been properly shut off.
Now it’s time to drain the old water heater. Hook up a hose to the water heater drain and open the valve, leaving the cold water supply open to flush out any debris. Then, shut off and disconnect the cold water supply and let the tank drain completely.
Draining the tank can take time and may require cleaning out sediment in the drain valve and/or the hose. If gravity alone isn’t enough to clear the tank, you may need a small pump designed to move water.
When the tank is empty, remove the flex supply lines and disconnect the power. If flex lines are already connected to the supply, there should be plenty of pipe to which you can connect the new fittings. Otherwise, be sure to leave 3–5 inches of pipe for the new connections.
Remove the temperature/pressure relief valve plumbing, and if reusable, save it for reinstallation on the new water heater. Remove the electrical wire nuts, but don’t cut the length of wire until you know what is needed for the new heater installation.
Remove the old water heater.
Before you take your old water heater to the landfill, check to see if your waste management provider has an appliance recycling program.
2. Clean Up
Clean up your working space to prepare for installing the heat pump water heater.
Inspect all remaining fittings to make sure they are sound and functional. If they need to be replaced, now is a great time to do it. If you are replacing the cold water valve, you will need to shut off water to the whole house.
3. Prepare The Plumbing
Materials: Water supply pipes; Shutoff valve; Pipe for temperature and pressure relief valve; Teflon tape; Mixing or anti-scald device (optional); Pressure reducing valve (optional); Thermal expansion tank (optional); Construction channel or wood blocking (optional)
Your new heat pump water heater may require a couple of changes to the location and plumbing. First, it may have a larger diameter than your old water heater, and six inches of clearance from the wall is recommended. Refer to the installation manual for clearance requirements around the exhaust fan.
Use construction channel or wood blocking to space the heat pump water heater away from the wall. This can help secure seismic strapping and reduce vibration transferring from the straps to the wall.
Second, unlike the old water heater, the water inlet and outlet lines on some heat pump hybrid water heaters may be located on the side of the unit instead of on top. You will need longer supply lines to reach the inlet and outlet. Use solid pipe and flexible pipe connections if they are permissible according to local code. These do not require soldering, clamps, unions, or glue. Use Teflon tape on all threaded connections.
Do not reuse the old piping — it’s not worth the risk of leaks.
If you are installing your water heater in a closed water system, which lets water in through the supply line and doesn’t let it back out except through drains and sewer lines, you will need to install a thermal expansion tank to prevent problems resulting from pressure buildup. Install the temperature and pressure relief valve and a discharge line per the manufacturer’s instructions and local code.
Install a shutoff valve in the cold water inlet line near the water heater. If you are not using flex connectors, use unions in the hot and cold water supply lines to make removal of the water heater easier for service or replacement. If required by local code, install a mixing valve or anti-scald device in the domestic hot water line and a pressure reducing valve in the cold water inlet line.
4. Position The Hybrid Water Heater
Materials: Drain pan; Rigid insulation foam pad; Seismic strapping; Shims (optional); Stand (optional)
Place the rigid foam pad and drain pan for the heat pump heater on the floor, or if local code requires, place the drain pan atop a stand. Move the water heater onto the drain pan. Ensure that the control panel is facing outward for easy access. Level the unit using shims, if necessary.
If required by local code, install seismic strapping.
5. Connect Water Pipes
Materials: Pipe insulation (optional)
With the heat pump water heater in place, connect the supply lines to the cold water inlet and hot water outlet.
Insulate the hot water supply line with a polyethylene or neoprene foam pipe sleeve. This reduces heat loss and can raise water temperature 2–4 °F hotter than uninsulated pipes can deliver. You also won't have to wait as long for hot water when you turn on a faucet or showerhead, which helps conserve water and maximize energy savings.
6. Address Condensate Management
Materials: PVC pipe; Condensate pump and vinyl tubing (optional)
Unlike your old water heater, the heat pump unit produces condensate that needs to be drained. If there is a nearby floor or sink drain, attach PVC pipe to the water heater’s drain port(s) and route the condensate in a downward slope.
Rather than using an elbow to connect the condensate line to the tank, use a tee fitting with an unglued cap that can be removed for easy cleaning access.
If there is not a drain nearby, a condensate pump is required. Refer to manufacturer instructions before connecting the condensate drain line into an existing drain or discharge line. Most condensate pumps can be attached to a wall hanger and plugged into a standard 120 Volt outlet. Ensure that the tubing is connected securely with hose clamps to the pump output and drains to a suitable termination point. If a drainage pipe is directed outside, make sure the pipe will not freeze by having it terminate at least 6 inches above the ground, and making sure there are no low spots in the tubing outside. Install the condensate pump per manufacturer instructions. Verify the pump is working properly by filling it slowly with water until the pump engages.
The tubing from the condensate pump may need to be routed up and over the surrounding rooms. To help pull the tubing through insulation and/or areas with limited access, attach a long PVC pipe to the tube and gently pull the tube through. Tubing and pipe hangers can be installed on condensate lines to prevent slippage and achieve a cleaner look.
7. Fill The Tank
Open the cold water valve slowly at first to make sure there are no leaks. Then, fill the heat pump water heater. Meanwhile, turn on the highest hot water faucet in the house to allow air to escape as the tank is filled and double-check the piping for leaks. Don’t worry if some rusty water gets pushed through. When the hot water faucet in your house has a steady stream, you’ll know the tank is full. Run the faucet for 3 minutes after a constant flow has been achieved before turning it off.
8. Complete Electrical Connection
When the tank is full, connect to the electrical supply according to the manufacturer’s instructions. Use new properly sized wire nuts to connect the wires. Then, turn on the power to the heat pump water heater at the breaker. Use a voltage meter to verify proper voltage. Make sure all cover plates are properly installed.
9. Start The Hybrid Water Heater
Most water heaters will go through a self-check and verify that the tank is full of water, that it has sufficient power, and that there aren’t any errors. This can take up to five minutes (you may hear a series of clicks and the fan may turn on and off).
The first heating may use electric resistance to deliver hot water to you as quickly as possible, even if the unit is set to Hybrid or Heat Pump mode. The compressor and fan will not operate until the water has reached a certain temperature. Your hybrid water heater will default to Hybrid mode. This setting is ideal for daily use because it uses the heat pump primarily, activating the less-efficient electric heating elements only when demand is high. Refer to the manufacturer’s instructions for information on other operating modes.
Using the digital controls on the heat pump water heater, set the water to the temperature you measured in the beginning.
Congratulations! You’ve successfully installed your new heat pump water heater, and you’re set to enjoy years of reliable hot water and savings.
- Perform preventative maintenance on your heat pump water heater as directed by the manufacturer’s instructions. This may involve:
- Cleaning your heat pump water heater’s air filters by wiping them with a damp cloth, rinsing them underwater, and allowing them to air dry.
- Manually operating the temperature and pressure relief valve to ensure it is working properly.
- Draining and flushing the tank to remove any sediment that has built up. Do this once a year, unless your house is supplied by a high-sediment well.
- Inspecting and cleaning the drain pan and condensate drain lines. (Your water heater will sound an alarm and notify you if these are necessary.)
Write down the purchase date, model, and serial numbers of your heat pump water heater, as well as the date of each filter cleaning.
If you’re stuck, or if things don’t seem right after you’ve installed your heat pump water heater, don’t panic. All installation guides have troubleshooting sections to help you through challenges, and water heater manufacturers have customer service lines to walk you through each step. (Keep in mind that not all manufacturers have weekend hours.) Assuming you’ve already double-checked the manufacturer’s instructions, contact a knowledgeable installer who can lend you a hand.