Do your homework on heat pump water heaters
Posted in Appliances, Climate, Energy conservation, Heating and cooling on May 27th, 2011 by Susan – Be the first to comment
Heat pump water heaters are expensive and not well suited to our winter climate. (Image courtesy energysavers.gov)
Heat pump water heaters can save you 50 percent on your water heating costs – or can they?
Recent news reports have been touting the marvels of new heat pump water heaters (HPWH) with claims of energy savings of 50 percent over standard hot water tanks. Our Conservation staff is hearing from more and more customers who are interested in purchasing one of these units. Our advice: Purchase with care and do your homework. These units can save considerably over a standard electric water heater, but they are expensive, $1,500 – $2,000, and may not perform as expected during the long, cold winters of Eastern Washington.
Heat pump water heaters work by removing heat from the air and transferring that heat to water. This makes the conditioned air cooler. That’s fine in the summer, when the air conditioner is running, but in the winter, the only air warm enough to supply a sufficient amount of heat is in the conditioned space of the home. This is air you’ve already warmed with your home’s heating system. By removing heat from your home to warm your water, you‘ll lose much of your water heating savings by having to run your heating system more.
Other requirements of a heat pump water heater that need to be addressed before you purchase are:
- Adequate physical space: Heat pump water heaters are generally larger (height, width, and/or depth) compared to standard water heaters. Limited space in your home may prevent the water heater from being installed in a desired location.
- Adequate air volume and circulation: Heat pump water heaters often require large enough areas and volume for adequate air circulation. Without this, a heat pump water heater’s performance is reduced, particularly if installed in a confined sealed space, such as a closet or a small room.
- Condensate removal: Access to a drain or to the outdoors is required for removing the heat pump water heater’s condensate, generated during operation. Often, existing water heaters will have a drain pan, but additional piping may be required for handling this.
- Noise: Heat pump water heaters hum or whir when the system operates. Depending on the model and location, the noise may be unacceptable.
- Exhaust air: Heat pump water heaters exhaust cool, dehumidified air into their surroundings, which may not be desirable in winter. This means the units will need to turn off heat pump operation to stop exhaust air. That most likely means using a back-up water heater, probably an electric resistance heater, further reducing any energy savings.
For more information on heat pump water heaters:
The Northwest Energy Efficiency Alliance has developed specifications for heat pump water heaters that will help manufacturers meet the energy efficiency requirements for customers living in northern climates.
Washington State University Energy Efficiency programs has an easy-to-read fact sheet on HPWH.




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