a blue tesla model 3 on the left with a rheem hybrid heat pump water heater on the right in a garage

Are you looking into heat pump hot water heaters? Heat pumps are an excellent choice for homeowners looking to save energy and to cut their energy bill. Why are these hybrid water heaters quickly becoming popular?

Heat pump water heaters (HPWHs) are highly efficient. They use thermodynamics and electricity to extract heat from the surrounding air and transfer it to your hot water tank. Unlike gas and fossil fuel heaters, heat pumps use ambient temperature to heat water, saving 70% or more on energy costs.

This article will provide you with everything you need to know when installing a HPWH in the garage. So, keep reading to learn how to get the most out of your heating unit so you can rely on it for years to come.

Can You Install Heat Pump Water Heaters in the Garage?

Yes, in most cases, garages are an excellent place to install heat pump water heaters. Garages keep the unit protected, it’s out of the living space (because the heat pump makes noise), and it’s generally closer or easier to reach electrical and plumbing, among other benefits.

Before installing a heat pump water heater in your garage, here are a few factors to consider:

  • The size and power rating of the unit – heat pumps are sized much like conventional water heater tanks. We have a whole article on this, but it depends on your usage needs of your household, among other factors.
  • The size of your garage – The other sizing requirements is to make sure your room is big enough (has enough cubic feet of ambient air) to supply the heat pump unit sitting on top of the tank. For both of my heat pump water heat renovation installs, the 40 and 50 gallon tanks needed above 700 cubic feet of space (room size) to adequately supply the heat pump with air. You must check the manufacturer’s install guidelines for its individual specs.
a closeup of the heat pump water heater unit on top of the hybrid water heater tank with a green graphic indicating efficiency and money savings
A heat pump water heater in the garage of one of our net-zero Florida solar renovation home projects.
  • Your garage’s ambient temperature – water heaters work best in higher temperatures. Since warm air contains more heat, the system becomes more efficient. If your garage is cold, it may take longer for the water heater to reach a high enough temperature. This works great in southern states like Florida, Texas, Georgia, etc, but you’ll have to check for the northern states. Many manufacturers now carry cold climate heat pump water heaters so you can use them way up north.
  • Temperature fluctuations – garage temperatures fluctuate depending on the season and when the garage door is left open for vehicles to enter and exit. Temperature fluctuations can affect how long it takes to operate efficiently (which uses more energy as well). The good news is, these are called hybrid water heaters because they still contain the elements of a conventional water heater. So you can switch between heat pump only, hybrid (it uses both), or only the conventional coils (fastest heat up time but more energy costs).

Pros and Cons of Heat Pump Water Heaters

It’s a good idea to weigh the advantages and disadvantages of heat pump technology in general. Your own home and your own garage will have unique conditions and aspects to it that will determine whether heat pumps will be a good idea or not.

In general though (in my own opinion), I personally believe that garages are a perfect place to have them installed. If you’re up north and have a cold climate unit, that’ll solve that problem. But I’ve installed my heat pump water heaters in the garages when I do these these netzero home projects.

a blue tesla model 3 on the left with a rheem hybrid heat pump water heater on the right in a garage
The yearly savings (About $400 per year) from just swapping to a heat pump water heater vs. a conventional one actually powers the Tesla Model 3 for an entire year! Now that’s some crazy efficiency.

Heat Pump Water Heater Pros

  • Energy-efficiency – air source heat pump efficiency can go as high as 300%, cutting your energy spent on water heating by 70% or more vs. a conventional water heater.
  • Eco-friendliness – unlike conventional gas and oil water heaters, HPWHs do not add harmful greenhouse gases to the atmosphere. They expel no emissions unless you have a dual-fuel system that runs on electricity and gas. The only “emissions” they really have is colder are coming off the fan exhaust side (can cool down your garage – excellent in hot climates), and water from the condenser drain line.
  • Low running costs – heat pump water heaters run on electricity, which costs less than fossil fuel. The manufacturers usually provide a longer warranty period vs. regular conventional water heaters. Both of my A.O. Smith and Rheem units have a 10 year warranty, for example.
  • Dual function – heat pump water heaters can simultaneously function as a heating and cooling unit. The outdoor unit contains the heat exchanger, expansion valve, and compressor. The outdoor unit’s role can sometimes be reversed to expel the excess heat in your home to the outside environment.
two men installing a heat pump water heater in a garage
Installing the A.O. Smith unit in our first netzero solar home renovation.

Heat Pump Water Heater Cons

  • High up-front costs – heat pump water systems are a great choice, but the high up-front cost might be off-putting. On average, plan to maybe spend double for the unit itself vs. a conventional hot water heater. The install should be nearly the same. The only real difference is the condenser drain line, because the heat pump unit will dehumidify and produce water, much like your regular HVAC system.
  • It can take longer to heat water – with HPWHs, you’ll have to wait for hot water longer than you would with your old water heater. Also, pushing the unit too hard too fast can significantly reduce its lifespan. The good news is, the computers inside these units can detect your water needs to hybrid/auto-switch between the conventional coil heaters and the heat pump unit. My A.O. Smith one does this really well, and has provided constant hot water for long periods of time. The outside ambient water temperature probably has to be fairly warm already though (I’m in Florida).
  • Decreased performance in extremely cold climates – unlike furnace water heating systems, heat pumps rely on ambient temperature, which can affect their efficiency. Extremely cold weather significantly minimizes your unit’s efficiency.

We recommend checking the manufacturer’s ratings, such as the unit’s energy and seasonal performance factors. The energy factor measures how much hot water your model produces per unit of fuel. The higher the number, the more efficient the system.

The seasonal performance factor is another measure that describes how efficiently an air conditioner performs. It’s an average ratio of the output energy over the electrical input energy. 

The greater the seasonal performance factor, the more efficient your unit is, because your heat pump water heater is producing a proportionately large amount of heat energy relative to the electricity it uses.

Will an HPWH Cool Your Garage?

Heat pump water heaters can “reverse” their function and work like an air conditioner by pulling warm air from inside your garage and replacing it with cooler air. This is actually a massive benefit in the summer and hotter climates in general. However, since they are designed primarily for heating hot water, they may not perform as well for cooling the space. 

It can be challenging to keep your garage warm if you live in an area with a frigid climate. It would be best if you switched to a standard water heater instead. 

A standard water heater is a great way to maintain a comfortable temperature without spending so much energy. Traditional water heaters do not remove the heat (air) from your garage, making them sometimes more efficient and cost-effective when used in areas with lower temperatures.

However, if your garage becomes too hot in the summer, you may want to install a heat pump water heater. Doing so will help keep the garage at an ideal temperature during the summer months. 

Do Heat Pump Water Heaters Make Noise?

These units make noise. This is why I would highly recommend not installing these in any living space you normally hang out in. Check out this article, and the YouTube video below, where I actually measure the decibels of both the A.O. Smith model (from Lowes), and the Rheem from Home Depot. For me anyway – neither of these units bother me when they’re in the garage and you can’t hear them from inside the house.


Using a heat pump water heater in your garage is a cost-effective and environmentally-friendly choice. The unit may be noisy sometimes, but it’s more energy-efficient than boilers and conventional water heaters. To make the most out of your HPWH, use it in areas with moderate heat and sun exposure.

Personally, I love these in the garage. If you have good conditions for a heat pump unit, I say go for it!


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