Warm Your Home

How a Heat Pump Works

It’s not a furnace, but it can warm your home. And it’s not an air conditioner, but it can cool your home. How’s that possible?

By Joseph Truini

PETER STEVENS, FLICKR

Of all the mechanical systems installed in homes today, few are as mystifying as the heat pump. It’s not a furnace, but it can warm your home. And it’s not an air conditioner, but it can cool your home. How’s that possible? Will it save you money? Is it effective at any temperature? Is it better than a gas furnace?


Here’s a brief explanation of exactly what a heat pump is and how it works.

Simply stated, a heat pump is an all-in-one heating and cooling device that’s designed to keep your home comfortable all year round. It consists of two main components: an indoor air handler and an outdoor heat pump, which is similar to a central air-conditioning unit. Inside the pump is a compressor that absorbs and then releases heat. In summer, the heat pump operates much like a central air-conditioner, absorbing heat from inside your home and expelling it outdoors. In winter, the process reverses and the pump absorbs heat from the outside air and delivers it indoors to heat your home.

IF HEAT PUMPS ARE SO WONDERFUL, WHY DOESN'T EVERY HOME HAVE ONE?

The amazing thing about a heat pump is that it can extract heat from cold air, because even cold air contains some heat. For example, if you go outside in 35-degree-Fahrenheit weather, it feels cold. But, it feels a lot warmer than if the temperature is 20 degrees, right? That’s 15 degrees of heat that aren’t in the air. It’s that ability to absorb heat from air—even cold air—that makes heat pumps reliable and much more energy efficient than single-source systems that only produce either cool or warm air. A heat pump doesn’t generate heat from scratch, which requires quite a bit of energy. Instead, it simply moves heat from one place to another.

You might be wondering: If heat pumps are so wonderful, why doesn’t every home have one? Heat pumps are ideal for regions with moderate climates, but are less efficient in areas with long, frigid winters. As a general rule, heat pumps are effective at temperatures around 30 degrees or so. Any colder than that and the pump will struggle to extract heat, causing it to run much less efficiently.

However, that doesn’t mean a heat pump is never a viable option in a cold climate. In cold-weather regions that require a lot of heat, the heat pump can be coupled with a gas furnace, something known as a dual-fuel system. When the weather turns cool, the heat pump produces heat and uses the furnace to blow warm air throughout the house. In very cold weather, when the heat pump can’t extract the necessary Btu, it automatically shuts down and the furnace does all the heating.

In predominantly hot-weather regions, where heating isn’t as important, the heat pump can be paired with an air handler. In this arrangement, the heat pump heats or cools the air and the air handler circulates it throughout the house.

For a lot of people, a heat pump can be a good way to save money on heating and cooling. If you’re not sure if it’s appropriate for your home, contact a local licensed heating-and-cooling contractor.