Don’t do it! The only reason to set your thermostat on emergency heat is if the regular heat is not functional. A heat pump is essentially a reverse cycle air conditioner, switching  the flow of the refrigerant backwards on cold days to absorb outside heat and bring it into your home. Moving existing heat is more energy-efficient than generating new heat with an electric-resistance heat strip in the air handler (indoor unit) of the air conditioning system. 

   But the heat strip is installed to function on days when the outdoor temperature dips toward freezing and below, and there is not enough warmth in the air for the heat pump to work efficiently. An internal sensor in the system recognizes when this happens, and will switch on the heat strip automatically—which makes the “AUXILIARY HEAT” or “AUX HEAT” light on your thermostat come on, indicating that the backup system has been activated temporarily.

   When you turn on “EMERGENCY HEAT” or  “EMER HEAT,” you are turning on the heat strip and locking off the heat pump, which increases the cost of heating your home and is not a good idea.

    Also see our blog posts Why is there a burnt smell when I turn on the heat? and How long does a home thermostat last? and Will closing doors reduce my heating and cooling costs?

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  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.