One of the greatest advances in home water heating technology is the heat pump water heater. The water heater is the second largest energy consumer in your home, after your heating and cooling system, so it makes sense to learn about this highly efficient product.
What is a heat pump?
Simply put, a heat pump is a machine that takes thermal energy (heat) from one area and moves (pumps) it to another area. Some examples of heat pump technology are air conditioners, refrigerators, and dehumidifiers.
How does a water heater heat pump work?
A heat pump water heater works by removing heat from the air around it and efficiently transferring it to the water stored in the tank. Think of when you have a dehumidifier running in your basement during these hot humid summer months. The dehumidifier is pulling in cool humid air, removing the moisture, and exhausting warm dry air. A heat pump water heater is essentially the same technology except instead of exhausting the heat energy, it transfers it to water in a storage tank and discharges cooler air.
Heat pumps can accomplish this by using the refrigeration cycle. When liquid refrigerant is compressed it gains heat. Heat is absorbed from the air in the room which is blown across a coil by a fan. This causes the refrigerant to boil into a vapor which creates super heated vaporized refrigerant. This superheated vapor travels through tubing around the water tank. The cooler water temp absorbs the heat and condenses the refrigerant vapor back into a liquid. This process causes the water in the tank to be heated without the use of heating elements The refrigerant is reused over and over again switching from vapor to liquid.
Heat pump water heats are often referred to as hybrid water heaters because they have backup heating elements that can be used in times of high demand. This graphic below may help explain how heat pumps work.
How do heat pumps save money?
Heat pumps are over 3 times as efficient as a standalone electric water heater. They are powered by electricity and use no fossil fuels such as natural gas, propane, or oil. Rather than heat up electric heating elements that use extreme amounts of electricity, they run a small compressor that uses very little energy. The compressor is all that is needed to transfer heat from the room to the storage tank. This in turn will save significant money on your electric bill. Once the water is heated in the tank, it stays heated by means of thick foam insulation for many hours.
Heat pump water heaters installed in New Hampshire are now eligible for $750 rebate from the state. This brings the cost of installation to about the same price as a regular water heater!
Are there any other benefits?
One benefit is that when the heat pump is running, it will also work as a dehumidifier. Since water heaters are typically installed in damp basements, this is a very useful side effect. No energy is wasted because your regular dehumidifier will now run less saving you even more money on electricity.
What are the cons?
Heat pump water heaters are more expensive. They cost more to purchase and take longer to install so the total installation price is usually higher. Government rebates are available that bring the price down.
Because they remove heat from the air around them, they can cool the room they are located in by a few degrees. If the water heater is in an unfinished basement, this is typically not a problem. It is sometimes beneficial as in the summer you are essentially getting air-conditioning for free! If the air in the room is cooled too much in the winter, the water heater can always be switch over the heating elements, or use a hybrid of both heating elements and heat pump. The hybrid mode is the recommended mode as it provides the perfect blend of efficiency and performance.
Heat pump water heaters remove humidity from the air and need a place to dispose of. The condensate can be piped to a nearby drain either by gravity or with the use of condensate pump. This is usually simple to do.
If you are converting from a gas fired water heater, you will need to have a 240 volt 30 amp circuit run for the new water heater. If you need a condensate pump installed, you will also need a standard 120 Volt receptacle for the pump to plug into.
The heat pump has a filter screen on it that needs to be cleaned of dust periodically. The frequency of cleaning will depend on the amount of time the heat pump is running and the air quality in the room.
Heat pump water heaters are great options for many homes and I strongly recommend them. They come with 10 year warranties so they are built to last. Available sizes are 50, 66, and 80 gallons so there is an option for every home. They don't burn fossil fuels. There is no risk of carbon monoxide. They require no venting to the outdoors. They are great for the environment and your wallet. Contact Advanced Plumbing for a consultation to see if a heat pump water heater is right for you.