When to use Emergency Heat on a heat pump

Emergency Heat setting can double billsEmergency Heat sounds like a wonderful feature for a heating system. It sounds comforting to push the “Power Boost” button during the blizzard. Especially in times of a winter emergency as defined by our central Indiana weather personalities on TV. I am waiting for the day I hear, “… that’s right Bob, we are bracing for our first 2 to 3.6 inches of snow tonight and we will be tracking it throughout your evening TV shows and by the way, you should be rushing to your thermostat and switching into Emergency Heat as soon as possible!

What is Emergency Heat and when should you use it? An Emergency Heat switch is found on most electric heat pump thermostats. Sometimes it is abbreviated as “Em.Ht.” and sometimes it is called Auxiliary Heat (Aux.Ht.). Gas furnaces do not have this feature. The Emergency Heat switch is very easy to understand; it simply turns off your heat pump. But you do not want to do this unless you enjoy electric bills that are twice what they should be.

Your heat pump is a very efficient means of heating your home. Read my previous blogs about heat pump efficiency. All heat pump systems in Indiana also have backup heating coils to assist the heat pump in very cold weather. The backup coils are similar to a much less efficient, portable space heater or the type of heat coils you would see in an old toaster. Electric heating coils are only about one-third as efficient as the heat pump. But fortunately they only account for about 15% to 20 % of your home’s total winter heating needs in Central Indiana. The more efficient heat pump is responsible for most (80% to 85%) of your winter heating. Unless of course you make the mistake and turn off the heat pump!

Do not turn off your heat pump! Some nasty advice is given, even from heating contractors who do not know any better, that you can use the emergency heat setting on your thermostat and “give the heat pump a break when the weather gets cold”. Well take it from me. This switch named “em. ht.” is misnamed. It has nothing to do with getting extra heating capacity or serving as a cold day setting. It should be named, “DOUBLE OR TRIPLE MY BILLS!” When you switch to “em. ht.”, you turn off your heat pump and now the more expensive backup furnace (toaster coils) are heating your home at two to three times the cost.

Don’t do this! Allow the heat pump to run and love it. New heat pumps are very efficient and they are designed to run non stop when you need it most so your heating bill is normal. Even older heat pumps are much better than the electric furnace. Heat pumps are so efficient that even if you need to raise the thermostat a degree or two on the worst winter days, you will still be better off in the normal heating mode and not switching to emergency heat.

If your heat pump is too old, then its ability to move heat may be less than what it should be. Call Precision Comfort Systems, your Central Indiana heat pump specialists, to evaluate your current heat pump. We can tune it up or eventually replace it so you are getting the most from the current heat pump technology.

When are you supposed to use this switch? If you find that your heat pump is not working (read how to test this on your own) then you can switch to emergency heat until a technician from Precision Comfort Systems can visit your home. Or perhaps a part needs to be ordered. Our technician may leave your system in the emergency heat mode for a short time until the heat pump can be repaired.

What if it is very, very cold? Cold weather is still no reason to turn off your heat pump. A heat pump is slightly less efficient in cold weather than it is in normal 20 to 30 degree winter weather, but it is never less efficient than the backup heat. So switching to Emergency Heat will always increase your bills. And most heat pumps will, in the normal heating mode, automatically use all the electric backup heat if necessary to heat your home. You do not get extra heat when switching to emergency heat. (If your heating contractor has custom wired your system to “save” some backup heat capacity solely for the Emergency Heat setting, there is no reason to do this and it should be changed back.)

Most important, be sure you have someone servicing your heat pump, that understands heat pumps. Call Precision Comfort Systems, your Central Indiana heat pump specialists, to service your heat pump.

About Energy Man Dan

Comments

2 Responses to “When to use Emergency Heat on a heat pump”
  1. Red says:

    Great advice, I’ve seen a lot of conflicting information here in Indiana and other cold regions. My issue is that when temps are below zero, the indoor temp drops about a degree a hour. I go to bed with the thermostat at 70 and wake to it at 63! I had it serviced before winter, the defrost sensor and board were replaced on the heat pump. I also wasn’t getting enough air flow, so I switched from a $25 air filter to a more basic one and sealed some air leaks around the return air duct. I’m thinking either my furnace isn’t supplementing my heat pump (but it does increase the temp in the morning when I switch to EMER HT). Or my heat pump set on 30 min defrost cycles is making a difference in the ability to keep up the temp? Thoughts?

    • Energy Man Dan says:

      Red, sorry for the delay in responding. You still have a problem but it’s hard to tell what’s wrong without a good service tech looking it over. First easy check is to make sure all banks of back-up heat are working. If they are, then I wonder if your airflow is so low that the electric heat is kicking out on a high temperature limit. Or it could be controls. If you live in our service area, call us and we can look at it. 317-867-2665.

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