There's no specific timeframe for using the emergency heat setting. If you need it for a few hours, the system should be fine. Or, keep it on until the unit thaws out or is fixed.
So, to sum up everything that we just covered, emergency heat is not supposed to run the way that your regular heat setting does—and it is especially not meant to run all day and night during the long, frosty winter months.
It does not damage your unit to run it. What emergency heat is, is heat strips like are in a portable space heater. They are really inefficient at heating, they draw a lot of electricity. But they create heat and work in emergencies. Should you use it?
This heating method works incredibly efficiently until the outdoor temperature reaches about 35 degrees. At this point, the heat pump has difficulty extracting enough heat from outside to keep up with the thermostat setting. This is when many people assume it's time for switching their heat pump to emergency heat.
Is Emergency Heat more expensive to run? If you have an all-electric heat pump, then the answer is a definite Yes! It is much more expensive to run your heat pump on Emergency Heat. And as the name implies, should only be run in an emergency until your heat pump can be repaired.
Short answer: No. Switching your thermostat to emergency heat or “em heat” just because it's cold outside will just raise your energy bills like crazy.
No, heat pumps do not need to run constantly in the winter. Most heat pumps are designed to cycle on and off as needed to maintain a comfortable temperature in your home. That said, if it is very cold outside, it may need to run continuously at times to maintain warmth in your home.
High energy bills
The cost of running your home on Emergency Heat would be astronomical. Turning to this setting switches the source of your heat from the heat pump to the electric heat strip, which is significantly less efficient and more costly.
Homeowners should expect auxiliary heat to turn on during colder temperatures, especially under 40 degrees. Your heat pump is an amazing appliance that can efficiently extract warmth from the outdoor air and transform it into cozy comfort inside your home.
Most standard heat pumps will function at 100% efficiency until the outside temperature reaches about 40° F. However, when the temperature dips below this, most heat pumps are not able to maintain efficiency. They become much less effective at temperatures between 20° F to 30° F.
Auxiliary Heat – This is the secondary heat source that turns on automatically. Emergency Heat – This is when you turn on the secondary heat source.
There are a few possible reasons your heat pump might be blowing cold air: Your heat pump is in defrost mode. There's an issue with your heat pump. It's below freezing, and you need a backup heat source.
Run warm water across the sides of your heat pump to begin thawing some of the ice. Do not attempt to use any tools or objects to crack the ice, as this can damage the coil and ruin your heat pump. Your heat pump comes equipped with an automatic defrosting function but try to clear some ice before attempting.
Your thermostat should be set to around 18-21°C, which is the lowest comfortable temperature that is economical too. Not only will this lower your heating bills, it will help to lower your carbon footprint and reduce your households' environmental impact.
The auxiliary heat setting on an HVAC unit usually turns on when you need heat fast. If this secondary heating system is constantly running, it may mean that the weather outside is very cold or that the thermostat is set higher than normal. It's also possible that a part of the heat pump is malfunctioning.
There's no specific timeframe for using the emergency heat setting. If you need it for a few hours, the system should be fine. Or, keep it on until the unit thaws out or is fixed.
This is less energy-efficient and will end up costing you more money in the long run. That's why we only recommend switching to emergency heat if your heat pump is no longer working. Even though your heat pump runs longer when it's extremely cold outside, it is still cheaper to run than when you use the heat strips.
If someone is at home in the daytime, 72° F (22° C) is a good start, but aim for 68° F (20° C). If everyone is away from home in the daytime or you're asleep at night, we feel 66° F (19° C) to 62° F (17° C) is best.
A furnace that's running non-stop is not necessarily bad. During the coldest days in winter, it is normal for a furnace to run almost constantly to keep the home warm. As long as the furnace is running efficiently and not making strange noises, the constant operation is likely nothing to worry about.
Contrary to popular belief, air-source heat pumps work amazingly well in winter—even in very cold climates.
They'll run more often or for longer on hotter days (just like conventional AC), but they shouldn't run nonstop without breaks. It is important to know that turning your heat pump system off and on (or regularly changing the temperatures throughout the day) will can cause it to work harder and less efficiently.
If you choose to switch on the back-up heat manually it will be called emergency heat. Auxiliary heat will come on and off as needed, emergency heat will remain on until you deactivate the setting. Therefore, unless your heat pump is malfunctioning, there is no need to turn on the emergency heat feature.
Unless it's very cold outside, the aux heat system shouldn't need to run too long. If it's above 40 degrees and your thermostat shows AUX HEAT for more than an hour or two, you might want to investigate.
According to the DOE, setting your thermostat back 7°F to 10°F for 8 hours a day from its normal setting can help you save up to 10% in energy costs. This means keeping your thermostat around 78°F in the summer (higher when you're asleep or away) or around 68°F to 70°F in the winter (lower when you're asleep or away).