FAQs - Heat Pumps

Heat Pump Water Heaters

What is a Hybrid Water Heater?

Electric heat pump water heaters are often called Hybrid water heaters which refers to the fact that they have a heat pump system and also electric resistance coils for emergency or high demand heating.

Will it affect how much hot water I have or how hot the water is?

No - if you choose the correct size tank, a good quality Hybrid water heater will give you all the hot water you need when you need it. You can adjust the temperature to suit your needs.

How does an electric Heat Pump Water Heater work?

Here is a great video that explains how heat pumps work. A heat pump water heater looks pretty much just like a regular water heater except that it will have a blower that sucks air from the room and blows it back out. The air that comes out of the blower will be cool because the heat pump pulls the heat out of the air to transfer to the water. This is just the opposite of a refrigerator that blows out warm air to keep the inside cool. Most HP water heaters have multiple modes that you can select - the most energy saving is Heat Pump only mode. Hybrid mode will activate a resistance electric heater if the unit is struggling to keep up with the demand (several people showering at once for instance). Since they are electric and digital, most come with apps which allow you to turn it off or adjust the temperature remotely - this comes in handy if you forget to do that and then remember while you are on vacation.

Where can I install a Heat Pump Water Heater?

They can go anywhere, but since they cool the space they are in, it is best if they are in a garage or basement or large utility room that doesn’t need to stay warm. They will de-humidify the air so they are great for slightly damp basements.

How much will a Heat Pump Water Heater Cost?

This will depend somewhat on the brand and the size - they typically come in 50, 65 or 80 gallon tank sizes and vary from $1,000 - $1,800. If you are replacing a conventional electric water heater, you may be eligible for a rebate or incentive from your local utility. Ask your installer about this.

Who makes the best Heat Pump Water Heaters?

Many brands make heat pump models, but the highest energy efficiency rated models according to this website - EnergyStar.gov - are the models from Rheem and AO Smith. They are also consistently among the top contenders in the Best Heat Pump Water Heater reviews. The fans in the units make some noise - much less than a power vent gas model, but if your existing unit does not have a blower this will be a new experience. If the unit is in the basement or garage, you will hardly notice it. Some models are quieter than others. The Rheem Prestige models are the quietest on the market, but you can find the decibel ratings in the product specs if you are interested.

How do I get a Heat Pump Water Heater installed?

Most brands do not recommend doing this yourself, but if you are a qualified plumber - go for it! Go to Angies List to find a highly rated water heater installer in your area and call them to make sure they install Heat Pump models. If you have a gas water heater now, be prepared that some installers may tell you that you are crazy to switch to a heat pump. That may be because they are more comfortable installing gas models and that is a clue not to work with that installer. Call around until you find an installer that is enthusiastic about heat pumps. If you know what brand you want to install, go to their website and they will recommend certified installers in your area.

How much will I save per year in operating costs?

This will depend on what type of water heater you have now, how much gas and electricity costs in your area, and how much hot water you use. You can get a pretty good idea by doing the following. Look for the yellow energy guide sticker on your current water heater. It will give you a dollar value for the Estimated Yearly Energy Cost. Then go to this website - AHRIdirectory.org - and find the same information for the model you are planning to install. Select the brand from the “Brand name” drop down menu, choose “heat pump with tank” from the “select energy type” drop down menu, choose “storage” from the “select heater type” drop down then hit “search.” When the models populate select the model you are interested in then click on the yellow Energy Guide label at the right. Most likely, you will save over one hundred dollars per year. The best gas models will have Estimated Yearly Energy costs of over $200 and a good heat pump model will be in the low $100 range.

Heat Pump Furnaces

Isn’t Electric Heating expensive and bad for the environment?

Many years ago when electricity was primarily generated from burning coal, electric heating was not a great alternative to natural gas heating. But now the grid is much cleaner and is getting cleaner every day. It is important to choose efficient electric heating devices however. Electric resistance heating is the technology that is used in toasters and some small electric heaters. It has also been used for electric baseboard heating in some older homes. It is convenient because a lot of heat can be generated in a relatively small device, but it is expensive because it takes a lot of electricity to generate the amount of heat that is required for a whole home. This type of electric heating should be avoided. Electric heat pumps are 3- 5 times more efficient than electric resistance heating, so it takes much less electricity and money for the same amount of heat. Because of this amazing efficiency, heat pumps are cheaper to operate and much better for the environment than electric resistance heating and even better than gas heating. These are the systems you want.

How does a Heat Pump Furnace work?

A heat pump furnace system works in the same way that a household air conditioner works except that it can both cool and heat your home. It is essentially like an air conditioner that can run one way to cool, and then run the other way to heat. In some ways thats all you really need to know, but if you want more info…. it starts with a compressor/fan unit that is located outside your house. It looks just like the compressor/fan for an air conditioning system but it is typically a little bit larger. That unit extracts heat from the outside air by blowing air across coils that contain a “refrigerant" that has been cooled through a mechanism of adjusting the pressure in the refrigerant lines that I won’t try to explain because it is a little complicated. But the bottom line is that this fluid is so cold that it is warmed up even by cold air outside the house in the winter. Then the fluid is pressurized which raises the temperature significantly, and pumped into the furnace unit that is located in your basement or utility room. The furnace warms air by blowing it across coils with the hot fluid inside and the warm air is then blown through your house to heat the rooms. This cools the refrigerant which is then de-pressurized which cools it further so it can be re-warmed outside. I hope that makes some kind of sense because it is a little bit magic.

Why is it so efficient?

Because the heat pump is only moving heat from outside, rather than creating heat, it is a very efficient process that utilizes existing heat to concentrate it in one place. The only energy required is to run the pumps and the fan which require very low amounts of energy. The efficiency of heat pumps has been increasing steadily as the technology improves because manufacturers have found ways to pressurize the fluid more effectively with higher efficiency pumps etc.

What happens if it gets really cold outside?

At lower temperatures, the heat pump has to work harder to heat your home. At some point - usually between 10 - 25 Degrees F depending on how efficient your heat pump is - the heat pump can not do all the work on its own and needs the help of resistance electric heat strips. Because resistance heat is much less efficient, the system should be designed to avoid the use of the heat strips as much as possible. They will typically only come on in very cold conditions and for very short periods or when the system is asked to warm the house after it has been left cold for a long time. Even in this situation, they are still more efficient than most other systems. If you think about it, there are very few days per year that are really really cold - the rest of the time it is more moderate and in those times the heat pump will need no additional resistant heat.

What if my house is not well insulated?

The first thing to do whenever you are thinking to upgrade your home heating is to make sure your house is well insulated. You will save money and be more comfortable whatever heating solution you use. Heat pumps are more sensitive to poorly insulated homes because they do not have the brute force of a gas system. A gas furnace can supply very high heat to compensate for poor insulation, although that is a terrible waste of money and energy. Maker sure your home is well insulated before installing a heat pump furnace.

I have heard that heat pumps make the house feel colder - is that true?

This should not be the case. The difference with heat pumps is that they do not provide really hot air out of the vents like a gas furnace does. The gas furnace will turn on and supply intense heat for a short time to warm the house, then turn off to let the house cool and then turn back on etc. This means that the house temperature is continually fluctuating as much as 5 degrees and it means that the air out of the registers is always really warm. A heat pump furnace will run much more continually and supply just enough heat to maintain the temperature, so the air out of the vents will not feel as warm. But, the house will typically stay very near the exact temperature you set on the thermostat with very little fluctuation. The additional air flow from the more continuous operation means you will have very clean air in the house due to the constant filtration. With a modern heat pump furnace it is common to feel an improvement in comfort compared to the gas furnace that was replaced.

What is a Ground Source Heat Pump or Geothermal Heat Pump?

The heat pump technology we were discussing above takes heat out of the ambient air outside your home and pumps it into your house. Those are air source heat pumps. The other source of warmth is the ground outside your home. A ground source heat pump is very similar to the air source heat pump but instead of blowing air across tubes containing refrigerant in the condenser unit outside your house, those tubes are buried in the ground. Ground source heat pumps are even more efficient typically than air source heat pumps because the ground temperature a few feet below the surface is pretty much 55 degrees all year round. If your home is in a suitable location with access to a space where coils can be buried, these systems can be an excellent solution with very low operating costs. Here is a website with more info and a good video that explains geothermal heat pumps.

What’s the story with air filtration systems?

Because a heat pump will operate with nearly continuous air flow to maintain a comfortable temperature, the air in your home will run through the filter more often. This will result in nicely filtered indoor air. Air quality around the US is surprisingly bad - especially in larger cities. A good quality 4” filter will take care of most fine particles, dust, allergens etc. Many installers will try to sell you an expensive UV or chemical air filtration system, but be sure you research them thoroughly before you buy. I think there is very good reason to be skeptical of those expensive systems when a high quality 4” filter is more than adequate for most needs. 1” filters are not very effective.