With all the excitement of switching to heat pumps for space heating, many people are wondering if they should make the switch to heat pumps for domestic water heating as well. This post dives into the pros and cons of heat pump water heaters (HPWHs) so you can determine if a HPWH is the right choice for your home.
What is a Heat Pump Water Heater?
Water heating accounts for about 18% of your home’s energy use and is typically the second largest energy expense in any home. In southeast Alaska, domestic hot water is most often heated by an electric resistance tank or directly from a connection to an oil-fired boiler, with on-demand electric or propane systems common as well. A HPWH uses a heat pump to move heat from the surrounding air into the water tank, rather than using an electric coil or burning of fuel to create heat. Since HPWHs simply move heat from one location to another, they can be 3-4 times more efficient than other water heating systems.
You might hear HPWHs referred to as ‘hybrids.’ HPWHs also contain electric resistance heating elements that can be used when the hot water demand exceeds what the heat pump itself is able to supply.
Considerations
Before choosing to switch to a HPWH, there are several things that should be considered:
- Units should be installed in 10’ x 10’ or larger rooms that are warmer than 35°F.
- Basements or other non-living areas are ideal because the HPWHs make some noise and have a cooling effect due to using surrounding air to heat the water.
- HPWHs will grab heat energy from their surroundings. If your present water heater is in your home, vs your garage or basement, this may not be the ideal switch for you to make.
- If you still heat your home with an oil boiler, waste heat from that system can be an ideal energy source for your HPWH.
- The units produce condensate that will need to be drained into a drain, sink, sump pump pit, or something similar.
- Adequate air circulation is needed for maximum efficiency, so units should not be installed too close to walls or ceilings.
- The unit’s air filter will need to be rinsed on a regular basis.
- In order to minimize heat loss, insulating the first few feet of incoming and outgoing pipe is recommended.
- There are 120V and 240V HPWHs. Factors such as ease of installation, cost, household size, electrical panel and service realities, and household hot water demand play into which unit would work best. More information on these can be found at the end of this post.
HPWH Pros:
- Up to 3-4 times more efficient than other types of water heaters
- Can save households $80-$230 annually on water heating bills (according to a study by Rewiring America)
- This can vary based on climate, water usage, household size, etc.
- Savings may not be as significant in communities with lower electrical rates if switching from a traditional electric water heater to a HPWH
- Reduces carbon footprint (if switching from a fossil fuel system)
- Help dehumidify the space they are in
- Wifi controls so you can manage heating schedules and track energy usage from your phone
HPWH Cons:
- Require a large space such as a basement or garage / should not be placed in an internal closet
- Only heat water at a rate of 7 gallons/hour (GPH) in heat pump-only mode
- If in hybrid mode (heat pump and electric resistance at the same time), can heat about 27 GPH
- Cools the surrounding space by about 3-5°F
- Upfront costs
- HPWHs cost between $1,200 and $2,500, plus labor for installation, and any electrical set up that is needed
- Contractors to install and service HPWHs are limited. Alaska Heat Smart will post contractor information as it becomes available.
The Bottom Line
HPWHs can provide an energy efficient and cost-saving option for water heating, but as with most things there are some downsides. Before investing in a HPWH, be sure to research unit types, installation requirements, warranties, your home’s electrical infrastructure, and contractors who can install and provide repair services. If you have already performed simple energy efficiency upgrades in your home and have the ideal space to install a HPWH, this can be a great option to take your home’s energy efficiency to the next level.
If you want to have HPWHs stuck in your head, check out this fun HPWH music video!
Alaska Heat Smart would love to hear about your experience with HPWHs! Contact ria@akheatsmart.org to share your experience or ask any questions.
Helpful Resources:
Efficiency Maine HPWH Information