How to Install a Hybrid Water Heater (Heat Pump) in 15 Easy Steps: DIY Instructions

Rheem Prestige heat pumpRheem Prestige heat pump

If you are planning to replace your old water heater and install a new and efficient one, consider installing a hybrid water heater.

Hybrids are advanced, ultra-efficient, and easy to install.

So, keep reading to learn more about how to install a hybrid water heater yourself.

Hybrids, also known as heat pump water heaters, are ideal for households located in warmer regions and where electricity is the only option.

They are designed to move the heat from the warm ambient air and transfer it to water inside the tank, cooling and dehumidifying the room at the same time.

Such heaters are often installed in locations such as basements, garages, and utility rooms, where they can take advantage of the warm surrounding air.

Hybrids provide cost-effective solutions helping homeowners cut their electrical usage for hot water by half or even more. This is possible because hybrids are designed to heat water with an efficiency that is more than three times higher than gas and electric models.

The heat pump installed on the top of the unit will carry most of the load, and if the demand is higher, the unit will turn on heating elements to add more power and deliver hot water at the desired temperature.

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Hybrids vs. gas water heaters

Now that we know how powerful and effective hybrids are let's walk you through 15 easy-to-use installation steps. This can also be a DIY project, but only if you are familiar with working with plumbing and electrical lines.

Be aware that according to the manufacturer, a licensed technician should install your hybrid water heater.

How to install a hybrid water heater: Installation tips

Reminder: Safety first. Never work on the electrical device with the power on. Note that improper installation can lead to electrocution, fire, or water damage.

Since hybrids are similar to electric water heaters, the installation is as simple, but you have to be aware that they are taller, wider, and might have a different location of plumbing and electrical connections.


Hybrids are designed for indoor installation only in a dry room that is not subject to freezing. The recommended ambient air temperature for the efficient operation must be above 45 F (or as required by the manufacturer).

According to the manufacturers, installers must observe required clearances around a water heater (as per some requirements, 6-7 inches is sufficient). Refer to your model installation manual for the specific data.

The floor underneath the heater must be strong enough to support its weight.

Install a suitable metal pan under the water heater to protect against damages due to water and condensate leaks.

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Air intake

The room must provide a sufficient amount of air, or if combined with the adjacent room and connected with the louvered doors. Check the manual that came with your water heater.


Your hybrid water heater may be ducted to the outdoors or some other suitable place (recommendations can be found in the manual). When installing a ductwork, make sure it is installed as straight as possible, and the maximum length is not exceeded.


Install piping that is suitable for potable water only.

Condensate drain

As an addition, the condensate line with the required slope must end in the appropriate drain and away from the water heater or other suitable spot using the condensate pump.


It is recommended to have a professional technician perform the installation.

Note: You might also need a permit for installation.

15 easy steps to install a hybrid water heater

  1. Shut the power off. Shut the power off to your existing water heater and leave it off until the new water heater is installed. Turn off the power on the main electrical panel by switching the breaker to the off position.
  2. Turn off the water supply. Use the main shut-off cold water valve to turn it off.
  3. Drain the old water heater. Empty the tank. Use one end of the garden hose and connect it to the drain valve located at the bottom of the water heater. The other end should run outside or terminate in the nearby drain. Be aware that it takes some time (a few hours) before all the water is drained.
  4. Disconnect the pipes. Disconnect the water pipes connected to the water heater. Depending on the pipe type used (copper, steel, or flexible metal braid pipe), you might have to cut it down or simply unscrew the fittings.
  5. Disconnect electrical connections. Disconnect the wires and label them to reconnect them back in the correct order easily.
  6. Put the new hybrid water heater into desired space. Place the new unit on a hard Styrofoam insulator or wooden blocks. Also, use a drain pan to collect potential dripping. Make sure a water heater is level before you proceed.
  7. Connect the fittings. The best way to connect your new hybrid to the home plumbing is by using copper pipes fittings and soldering them together. It is recommended to use unions on both the hot and cold sides so you can easily disconnect them when needed. The other option, which is much easier, is to use metal braided flexible hoses. If not sure, use the type of pipes to match the existing water line. Also, you might want to install a mixing valve to have better control of the hot water temperature and a new shut-off valve.
  8. Install a condensation drain line. Make sure that the drain line has a downward slope to allow proper drainage and away from the heater.
  9. Install a vacuum valve. If needed, install a vacuum valve near the top of the water heater to prevent potential damages to the heater.
  10. Check a TPR valve. Make sure that the temperature and pressure relief valve is installed correctly, including the discharge pipe, and both are functioning correctly with no obstruction.
  11. Expansion tank. In the case of the closed system, install an expansion tank to prevent extreme temperature and pressure increase.
  12. Fill the tank. Ensure that the drain valve is closed and open the main shut-off valve to fill the tank. Open a nearby hot water faucet for several minutes to allow the air to escape the tank.
  13. Reconnect the power. Follow the manufacturer's manual for the proper electrical connection.
  14. Turn the power on. Ensure that the water heater is full of water before turning the power on. This helps avoid dry firing and damage to the unit.
  15. Run the unit and check for leaks. After your hybrid water heater is installed correctly, air filter set, tank filled with water and connected to electrical power, press the power button to turn the unit on. Let it run a system diagnostics. Once complete, select the heating mode and temperature. The recommended temperature range is between 120 and 125 F.

Watch this video to understand better how to install a hybrid water heater yourself.

What's next?

The operating modes can be changed on the User Interface Module. Users can often select four different modes, including hybrid, electric, efficiency, and vacation modes.

The hybrid mode uses the heat pump as the primary heat source and, if needed, can engage heating elements.

The electric mode uses only heating elements and is the least efficient mode, while the efficiency mode utilizes only the heat pump making it the most efficient mode.

In order to keep your hybrid unit performing well and efficient, it is necessary to inspect, clean, maintain, and service a unit regularly.

In this article, we have provided basic instructions on how to install a hybrid water heater yourself, but if you don't have the right tools, knowledge, or have any doubts, the best is to contact a professional.

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