Myth: Heat Pumps are not efficient in cold weather

We have been conditioned to expect our appliances to cycle. The refrigerator turns off and on. The basement sump pump cycles. The clothes dryer runs until the clothes are dry and then turns off with a friendly melody letting you know that it has completed its job. If any of these machines did not cycle off as we expect, we would naturally think something is wrong. So when the weather gets cold and your heat pump runs constantly, myths are born. Like, “A heat pump is not efficient in cold weather” or “Turn off the heat pump when it gets cold” or “Heat pumps are not designed for cold weather climates.” All myths! Hopefully you have only heard these misunderstood rants from neighbors or the “expert know-it-all” at work. But if you’re hearing any of these myths from your heating contractor, you have some additional problems. If you’re hearing these profound “truths” from your spouse, then they are absolutely true, but you might accidentally leave this blog open on the home PC.

Here’s the truth. Heat pumps are tremendously efficient, even in cold weather. True, the efficiency does decline slightly as the temperature goes down, but even at very cold, single digit temps, heat pump efficiency is impressive and always better than any other setting on your thermostat. Do not turn the heat pump off by switching to Em. Ht. (Emergency Heat). Assuming your heat pump is working properly, never listen to any service technician who suggests “giving the heat pump a rest” unless you want to pay two or three times the cost on your electric bill.

So if heat pumps are so efficient, then why do they run all the time? Here is a blog from the past with more information on this.

But what if my heat pump really is broke and running non-stop? How will I know if I need service? Here are some tips to keep you from calling for service every time it gets cold.

But hold on! Not only does my heat pump run all day and all night, but when it does get cold outside, my home feels colder! What about that Mr. Heat Pump Expert?!

Great question. Here’s why. Your thermostat prioritizes the heat pump run time to maximize the cheap heat. The auxiliary heat (electric resistance heat, or back-up heat) is minimized since it is more expensive. Here’s how it works. Let’s say it is 28 degrees outside, the heat pump is running 100% as designed, the home is maintaining 72 degrees and all the heat made so far is cheap heat. Now let’s say it cools to 26 degrees outside. If the home temperature goes down one, or sometimes two degrees, this causes the thermostat to bring on the auxiliary heat for a very short boost to supplement the heat pump. The home temperature raises to a point just short of the thermostat set point and then the auxiliary heat turns off as soon as possible. Meanwhile the heat pump has been running non-stop throughout this time to maximize the cheap heat. So in cold temperatures, the heat pump runs non stop to maximize your cheap heat but your home may remain a degree or two below your thermostat setting.

What should you do, suffer? NO! The heat pump is very efficient so make it do its thing. Simply turn up the thermostat a degree or two in cold weather so you are comfortable. Do not suffer and submit yourself to the old myth that heat pump homes are cold. (I’ve heard service techs poorly advise customers, “Sorry, you will just have to get used to it”.) Remember, you are not really splurging or abusing the environment by adding one or two degrees. In very cold weather, adjusting a heat pump thermostat to 73 may be necessary to provide the 72 degree comfort you were initially looking for.

One tip that is not a myth. Resist cranking your heat pump thermostat by more than two degrees at a time. If you do this frequently, you will be calling up the expensive heat to accommodate the fast blast of heat. This will not hurt your heating system but it can raise your bill if you do this often.

More questions? Call Precision Comfort Systems. We’re the honest ones with much more precise information on your comfort systems.

Ed Kittle

General Manager Ed Kittle joined Precision Comfort Systems in 2020, bringing nearly four decades of industry experience. A past president and current Indiana ACCA chapter board member, Ed is also a licensed HVAC contractor and serves on the City of Indianapolis Licensing Board. He is certified by the Air Conditioning Contractors of America (ACCA) in heat loss, heat gain, and duct design.

Updated: July 27, 2024

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