Ready to take your home heating electric? Answering your heat pump questions

June 28, 2023 | 5 minute read

Heat pumps can both heat and cool your home. They use less energy than oil or propane furnaces, or window air conditioners. And there are incentives and offers that can make heat pumps more affordable.   

You can check to see if a heat pump is right for you. But like any new technology, understanding heat pumps leads to some frequently asked questions. 

For answers, we turn to Phil Bickel, a program manager at Efficiency Vermont. Phil (right) specializes in heat pumps. And to Jake Marin, who works for Efficiency Vermont on emerging energy technology. Jake (left) helped develop Vermont’s first heat pump program nearly a decade ago.  

How do heat pumps work?

Phil Bickel: The short answer is, like a refrigerator, but in reverse!  

Jake Marin: All heat pumps do is extract heat from one location and move it to another. A refrigerator extracts heat from the inside—where the food is—and dumps it outside, into your kitchen.  

PB: Heat pumps extract heat from the outdoor air, and then deliver that heat indoors. They can also switch direction, and cool your home in the summer.

Can a heat pump really “extract heat” from the air during a cold winter day?

JM: Yes. But to understand how, let’s explain heat pumps in more detail. 

Heat pumps contain a substance called a “refrigerant”. The refrigerant travels in pipes between the indoor and outdoor unit. By moving the refrigerant around, we’re “pumping” heat energy in a useful direction.  

The refrigerant in cold climate heat pumps is very sensitive to heat. This unique characteristic enables it to absorb heat from the outside air, even when it’s very cold out. This heat is then pumped inside the building and converted into useful heat to warm up our homes.  

Heat pumps also use a compressor to add pressure to the refrigerant, and an expansion valve to relieve pressure. By controlling that pressure, heat pumps can gather more heat from the outdoors and bring that heat inside a building. 

PB: When it's cold outside, there's not as much heat in the outside air. So, the compressor has to work harder to collect the heat and compress it down to deliver it inside. That's why heat pumps use more energy to run as the temperature drops. And at very cold temperatures, they reach a limit of how much heat they can provide. Even below 0°F, the refrigerant absorbs heat, and carries that heat back into the house. Then the process repeats, in a closed loop system, over and over again.  That’s how they add heat to the inside of a house even on a cold winter day.

What does heating a home with a heat pump “feel” like?

PB: We’re used to heating where an appliance pushes warm air out into the room, or out through the floorboards. Heat pumps work the same way. But they deliver warm air that’s not as hot as what you might be used to. Sometimes heat pumps only put out 90°F air. This may sound warm, but moving air feels cooler, so this air doesn’t feel hot.  

JM: Heat pumps get the temperature up to what’s set on your thermostat, and then maintain steady temperatures in the space. It’s what they're designed to do. They make a space comfortable because there aren’t as many fluctuations between warm and cold, as you might find with traditional heating systems. But if you stand near a heat pump and feel the air coming out, it does not feel hot, which sometimes throws people off.

Do I need a backup heating system if I go with a heat pump? 

PB: It depends! We've heard stories where people say, “I didn't have to turn on my backup heat system all winter.” We have also heard the opposite. We've heard stories where someone says, “I need a backup heat system. A heat pump alone did not work well in my home."

JM: Heat pumps are a no-brainer in smaller, tighter, well-insulated homes. That’s where they can provide 100% of your heating and cooling. It’s usually possible to heat 100% of your home with heat pumps, but it may not be cost-effective. Especially if you have an older or leaky home. That’s why many people opt to combine weatherization of their home with heat pumps. This can meet 80% of their heating needs. That may be the most cost-effective solution for most people.

PB: There’s nothing that says “this house does or does not need a backup system.” It’s a difficult thing to answer. It depends on your goals for your home, and your home’s unique characteristics. 

It’s best to talk to a professional. Efficiency Vermont’s participating HVAC contractors can help figure out any backup heating system you may need. They’ll also help you take advantage of incentives and rebates from electric utilities. And your heat pump may also qualify for federal tax credits and other rebates.  

Why should I use a heat pump instead of what I've always used to heat my home?

PB: First, there are cost savings. Most people will save money heating their homes with a heat pump versus fossil fuels. A heat pump is three times more efficient than a furnace or boiler running on propane, oil, or kerosene. And remember, the costs of those fossil fuels go up and down over time. Electricity prices are more predictable.  

JMThere’s also the decarbonization aspect. Vermont’s electricity supply is fairly low carbon. So, when we use electricity to heat our homes, it’s less carbon-intensive than burning fossil fuels. 

PB: Then there’s the cooling aspect. Heat pumps can also cool your home. An air conditioner and a heat pump are identical. Except heat pumps can also run in reverse. So, adding a heat pump is also adding cooling to any space. 

JM: Heat pumps are also an easy way to add heating and cooling to a space that doesn't already have it. They can heat or cool a room you’re fixing up, or a new addition to your home. They can also bring heating and cooling to underserved parts of your home. Places where your existing heating system doesn't really work well.  

How long do heat pumps last? 

JM: We estimate 15 years. But like any heating equipment, the better you take care of it, the longer it's going to last. Warranties on heat pumps are usually 7 to 10 years. 

PB: We’ve had more than 53,000 heat pumps installed in Vermont. We have not heard about many failing prematurely. So, only a handful of people had really bad experiences where the heat pump just stopped working. Most of these were covered under warranty.