Heat pump water heaters are quickly growing in popularity as a more efficient and more eco-friendly alternative to traditional storage tank water heaters. Compared to traditional water heaters, heat pump units have some significant advantages in certain areas. They’re also not without their downsides, which is why it’s important that you weigh the pros and cons if you’re considering a heat pump water heater for your home.
How Heat Pump Water Heaters Work
Heat pump water heaters work by using electricity to capture heat from the surrounding air and transfer it to the water inside a storage tank. Refrigerant is pumped through a closed loop. The refrigerant is initially extremely cold, allowing it to absorb heat from the air. It is then compressed before getting pumped through the coils inside the storage tank, which causes it to boil and become superheated. As it moves through the coils, all of the stored heat naturally flows out of the refrigerant into the water.
This process is essentially the same way that HVAC heat pumps heat (and cool) the air inside a building. There are also integrated heat pumps that can be used for both space heating/cooling and water heating, but they aren’t yet all that common in the US. Most of these units are designed to work with hydronic or radiant heating systems, although some can work with central forced-air heating systems.
Almost all stand-alone heat pump water heaters are hybrid units that also have electric heating elements like a standard electric tank water heater. The heating elements will usually come on whenever you’ve used up most of the stored hot water and work alongside the heat pump to bring the water back up to temperature faster. They will also turn on if the surrounding area is ever too cold for the heat pump to work effectively.
On most units, you have the option to run it in heat pump-only mode so that the electric heating elements never turn on. This is useful for saving energy, but it can present major challenges if your household has a high hot water demand. If the unit is in heat pump-only mode, you’ll have to wait at least several hours for the water to heat again after you’ve used most of it.
For a heat pump water heater to work properly, the surrounding air must constantly be between 40 and 90 degrees Fahrenheit. If the temperature is below 40 degrees, the unit won’t be able to keep the water hot enough since there is insufficient heat in the air for it to capture and transfer. If the air is too hot, the refrigerant won’t get cold enough to capture much heat.
Pros of Heat Pump Water Heaters
The biggest advantage of heat pump water heaters is their efficiency. Most heat pump water heaters are around three times more energy efficient than traditional electric water heaters, allowing you to significantly reduce your water heating costs. Heat pump units also have much lower energy demands than electric tankless water heaters. If you currently have a traditional electric water heater, you’ll typically save between $100 and $300 a year in electricity costs by switching to a heat pump unit.
Heat pump water heaters are technically much more efficient than gas tankless units. However, your water heating costs will often still be lower with a tankless unit than they would be with a heat pump. One reason is that tankless units heat on demand, which eliminates the additional energy needed to constantly keep a large volume of water hot. The other reason is that natural gas rates in most places tend to be quite a bit lower than electricity.
Another advantage of heat pump water heaters is that they have a significantly smaller carbon footprint, making them a more environmentally friendly option. The fact that they’re all electric means that they don’t directly produce carbon emissions like gas water heaters. The higher efficiency and lower energy demands also make them a more eco-friendly alternative to traditional and tankless electric water heaters.
Heat pump water heaters also don’t need as much maintenance and typically last a few years longer than traditional units. However, they still don’t compare to the average life expectancy of tankless water heaters. A properly maintained heat pump water heater will usually last around 15 years, whereas tankless water heaters have an average life expectancy of 20-25 years.
Cons of Heater Pump Water Heaters
Heat pump water heaters have two primary drawbacks: the amount of space they require and the fact that they continually cool the surrounding area when they run. For the unit to work effectively, it needs a minimum of 1,000 cubic feet of open air space around it. That means you can’t install it in a utility closet like a traditional water heater.
If your house has standard 8-foot ceilings, you’d need to have close to a 12-foot-by-12-foot space for a heat pump water heater to work effectively. If the space is too small, the electric heating elements will have to do most of the work, negating the benefits of the heat pump.
Many homes in Nebraska have their water heater in the basement. The fact that the heat pump continually pulls heat out of the air as it runs can result in the surrounding area getting quite cold and uncomfortable. You usually won’t notice much of an issue during the winter if your furnace is also in the basement and near the water heater, but it can be a problem in the winter when you have the AC on.
Another potential drawback of heat pump water heaters is the high cost. You can usually expect to pay somewhere between $800 and $1,600 for a traditional water heater. Electric units cost less than gas and are typically toward the lower end of this range. The average cost to purchase and install a heat pump water heater is around $3,500. However, some people end up paying closer to $6,000 or $7,000. If you currently have a gas water heater, the cost to switch to a heat pump unit will be higher due to the additional electrical work that’s required. The cost will also be higher if your existing water heater is in a location that won’t work for the heat pump unit, as then you’ll need to pay to have your plumbing redone.
The labor costs for installing a heat pump water heater are often higher than they are for traditional water heaters as well. It usually only takes an experienced plumber to disconnect and remove a traditional water heater and then install a replacement. Heat pump water heaters can sometimes take four to eight hours to install and set up.
Even though heat pump water heaters are more expensive, they can be more cost-effective than traditional units in the long run due to their energy efficiency. The amount you save on your energy bills with a heat pump unit will often eventually offset the higher initial cost. This is especially the case if you currently have a traditional electric unit.
John Henry's Plumbing, Heating, Air, and Electrical is a leading provider of professional water heater services in Lincoln and Omaha. We offer flat-rate pricing and free estimates, and our experts can handle all of your installation and repair needs. If you need to replace your old water heater, we carry a range of options to meet the needs of any size home. For more information or to schedule service, contact us today.
