EM heat means emergency heat. On a heat-pump system, turning it on tells your thermostat to stop using the outdoor heat pump and heat your home with the backup heat instead. If you do not have a heat pump, this setting does not apply to your heating system.
EM Heat vs. Regular Heat
With your thermostat set to Heat, your heat pump uses the outdoor unit to move heat into your house. When your heat pump needs help, your thermostat brings on the backup heat automatically.
Switch to EM Heat and your backup heating source takes over. In many homes, that means electric resistance heat strips. A dual-fuel system may use a furnace for backup instead.
If you're not sure what Heat, Aux, and EM Heat mean on your thermostat, start with the thermostat options your system gives you before changing anything.
EM Heat vs. Auxiliary Heat
You do not have to turn auxiliary heat on yourself. Your system brings it in automatically when the heat pump needs help reaching the thermostat setting or during certain operating conditions.
EM heat is different because you select it manually. On many digital thermostats, you will see Aux Heat appear automatically, while EM Heat is a setting you choose.
Keep in mind, seeing Aux Heat during cold Salt Lake Valley weather does not automatically mean your heat pump is broken.
When You Should Actually Use It
Use the emergency heat setting when your heat pump has failed or is damaged and you need backup heat while you wait for service.
Do not switch to EM Heat just because the temperature outside has dropped. Your heat pump and thermostat are designed to manage normal cold-weather operation without you manually changing to emergency heat.
If your outdoor unit has stopped working or is damaged, leave it off and schedule heat pump repair.
Why EM Heat Costs So Much More
If your backup heat uses electric heat strips, running EM Heat uses more electricity than normal heat-pump operation. Your heat pump moves heat from outdoors into your house. Heat strips use electricity directly to make heat, which takes much more electricity than moving heat with the heat pump.
If your system uses a furnace as its backup source, the cost depends on the furnace, fuel, and local utility rates.
If your heat pump has failed, emergency heat can keep your house warm overnight while you wait for repair. It is not meant to replace normal heat-pump operation for the rest of the winter.
What to Do If You Find EM Heat Already On
Do not immediately change the setting if you do not know why someone turned it on. First, check your outdoor heat pump.
If the outdoor unit is damaged or not running when your thermostat is calling for heat, leave it out of normal operation and have it checked. If the heat pump appears to be operating normally and EM Heat was selected accidentally, return your thermostat to the regular Heat setting.
If electric EM Heat has been on for several days, you've been heating the house with the heat strips instead of the heat pump. That extra electricity shows up on your winter bill.
Signs Your Heat Pump Needs Service
Having your heat pump inspected before using emergency heat is the best way to prevent high electric bills and potentially costly heat pump repairs. Call for heating repair if you notice:
- Your home does not reach the thermostat setting.
- Heavy ice stays on the outdoor unit instead of clearing during defrost.
- Auxiliary heat keeps running during mild weather.
- Your heat pump repeatedly starts and stops.
- The outdoor unit does not run when your thermostat calls for heat.
If you are asking when to use emergency heat because your heat pump keeps having one of these problems, the next step is finding out what is wrong with the equipment rather than leaving EM Heat on.
Heat Pump Service in the Salt Lake Valley
Scott Hale Plumbing, Heating & Air has served Salt Lake City, Utah County, and surrounding communities since 1984. Our technicians work on heat pumps throughout Murray and the Salt Lake Valley.
If your heat pump is not keeping your home warm or your thermostat keeps relying on backup heat, we will check the system and find the cause. If the equipment needs replacement, ask about available financing options. Schedule an appointment online or by calling us today.
Schedule online
