The Case for Heat Pump Water Heaters
Almost everyone has heard of a heat pump that provides home heating and cooling, even if they aren’t quite sure how a heat pump actually works. But heat pump water heaters? Yeah, it’s actually a thing.
While a heat pump used to condition air in the house can also heat water, a separate dedicated heat pump water heater installed in a conventional home heating and cooling system is a relatively new technology. So why would you want to consider having a heat pump water heater?
Given that water heating accounts for roughly 15 percent of your total utility costs, or somewhere around $600 annually for an average home, a heat pump water heater is well worth considering. However, as with any home plumbing system project, your individual mileage will vary and this particular appliance is not suitable for just any home or budget.
In this post we take a look at:
- How a heat pump works
- Heat pump advantages and disadvantages
- How a heat pump water heater works
- Heat pump water heater costs
- How to select a heat pump water heater
- Heat pump water heater installation and maintenance
How a Heat Pump Works
Heat pumps transfer heat, as opposed to a gas or electric furnace that generates heat. The most common type of heat pump for home heating uses electricity and refrigerants to absorb heat energy from outside air and transfers it to indoor air. To cool the house, the transfer works in the opposite direction: heat is removed from indoor air (thus cooling the space) and released outside.
To perform this transfer, a heat pump uses an outside unit that works in conjunction with an indoor air handler to distribute conditioned air to the interior spaces of your home. There’s a bit more involved technically, but that’s the basic idea.
Heat Pump Advantages and Disadvantages
Heat pump water heaters on the whole are two to three times more energy efficient than conventional gas or electric combustion units. And because electricity powers heat pumps, it’s an ideal application if you have solar panels, as it can further increase your energy efficiency. As Charles Cormany, Executive Director of Efficiency First California points out, “Anything that removes a combustion appliance is a good idea…they are a perfect solution in regions with small heating loads like most of California.”
In addition, there’s a little less hassle with a water pump water heater. There’s no pilot to light, and there’s no danger of a gas leak. Also, since the heat pump water heater unit doesn’t generate heat, and therefore isn’t hot to the touch on the outside, it’s a safer alternative if you have young children and/or pets likely to come into contact with it.
Nothing is ever perfect, however, and there are some downsides of heat pump water heaters to consider. These include:
- Sticker shock: much higher initial cost than conventional units.
- The compressor is noisy; if you insulate to reduce the noise, you reduce the amount of warm air for the unit’s use, which is counterproductive. So you either have to put up with the noise or place the unit far enough from living spaces that you won’t notice the noise.
- Because the unit generates cold air while in operation, it can make the house heating system work harder, which reduces overall energy efficiency and cost-reduction.
- Unit size requires larger space than conventional water heaters.
- Slower recovery than conventional units during periods of high hot water demand.
How a Heat Pump Water Heater Works
As you might expect, heat pump water heaters work under the same principle as a house heat pump, relying on electricity to transfer heat rather than to generate heat. A standalone heat pump water heater absorbs heat from surrounding air and transfers it at a higher temperature to water in a storage tank. There are limits to how much heat it can transfer, so electric strips are used to provide supplemental back-up heat.
A heat pump water heater works best when placed in an already warm space. The warmer the space, such as next to a conventional furnace, the higher the efficiency.
You can buy a heat pump that is integrated with a storage tank, or you can retrofit it to an existing conventional water heater. If you are renovating an existing HVAC system with a heat pump, or building a new construction, you can also install a heat pump that combines hot water heating with home heating and cooling.
Geothermal Heat Pump Water Heaters
While electricity is the most common fuel source for a heat pump water heater, homes with geothermal heat pumps, which draw heat from the ground in winter and from indoor spaces for air conditioning, have a different option to heat water called a desuperheater. Basically a desuperheater exchanges heat by using superheated gases from the heat pump compressor to heat the water.
Geothermal heat pump systems are much more expensive, several times more than a conventional home heating and cooling system. However, the return on investment is five to ten years due to considerable energy savings. Of course, heating water isn’t the primary concern here, but if you were to install a geothermal heat pump for home conditioning, it can be equipped to heat water as well.
Heat Pump Water Heater Cost
Generally speaking, heat pump water heaters are more expensive than conventional water heaters, roughly about twice as much. The trade-off, however, is heat pump water heaters are more efficient and have lower operating costs. They are also more energy efficient if properly installed and maintained.
According to Energy Star, a certified heat pump water heater can save a family of four about $350 annually in utility bills compared to a standard electric water heater. This adds up to a potential savings of $3750 and more over the lifetime of the heat pump water heater.
How to Select a Heat Pump Water Heater
Today many heat pump water heaters are available on the market. The selection criteria for a heat pump water heater best for you and your family is basically the same as a conventional water heater. These include:
- The size of your household and the number of showers and appliances likely to run hot water at the same time to guarantee adequate hot water and maximum efficiency.
- Overall cost, in addition to up-front purchase, including installation and yearly operating expense estimates.
- Warranties on parts and the unit itself.
Note that while heat pump technology dates back to the 1940s, heat pump water heaters are relatively new. They also require specific conditions to operate properly. If you do not have sufficient space, at least 1,000 cubic feet, and a temperature in that space that remains within 40º–90º Farenheit, a heat pump water heater does not operate efficiently. Garages are a popular location for heat pump water heaters because there is plenty of air and space.
Consequently, this is not a “take a trip to your local big box appliance store” sort of project. If you are considering a heat pump water heater, consult a certified plumber with experience in water heater appliances.
Installation and Maintenance
Because heat pump water heaters are taller than conventional water heaters and the compressor and control are usually top-mounted, plumbing is often routed differently. Some heat pump water heaters offer the option of ducting air from another space to provide sufficient air flow around the unit. Heat pump water heaters also require installation of a condensation drain or pump. Unfortunately, these requirements are at the very least problematic for smaller homes, and in most cases aren’t the wisest investment.
Just as a decision to purchase a heat pump water heater is best made in consultation with an HVAC (Heating Ventilation Air Conditioning) contractor, it is equally important to employ a knowledgeable professional to install and maintain the unit. If improperly installed, a heat pump water heater can fail to achieve the energy efficiencies you want. Perhaps even more annoying are the cold showers you and your family will endure after buying an expensive heat pump water heater, all because it wasn’t installed correctly in the right kind of space.
Also keep in mind that, like any large appliance, periodic maintenance is of major importance to prevent problems, extend working lifespan and maintain high levels of energy efficiency. When properly maintained, the average heat pump water heater can last anywhere from 10 to 15 years.
Ongaro and Sons — Your Water Heater Experts
Ongaro and Sons plumbers are knowledgeable in all the latest water heater technology and installation techniques. If you are considering a heat pump water heater, Ongaro and Sons offers quality service from experienced plumbers.