Rebate-eligible heat pumps can reach over 400% efficiency in mild temperatures and can maintain well over 200% efficiency even into negative temperatures. This is why turning off a heat pump in frigid temperatures and opting to use a fossil fuel boiler or furnace instead is a mistake.
People do not need to turn their heat pumps off. Residents should make sure their supplemental home heating systems are on and operating. Set the thermostats to a degree or two lower than heat pumps.
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.
Heat pumps do not operate as efficiently when temperatures drop to between 25 and 40 degrees Fahrenheit for most systems. A heat pump works best when the temperature is above 40. Once outdoor temperatures drop to 40 degrees, heat pumps start losing efficiency, and they consume more energy to do their jobs.
Frost and ice shreds may also collect around the heat pump. However, if extreme amounts of ice and snow buildup over the unit, it's strongly recommended to switch it off or to 'emergency heat' to remove the snow. The easiest way to get the snow off the heat pump is by pouring warm water over time.
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.
Freezing rain will cause the top of the unit to freeze over and in some cases the blade itself will be unable to turn. Solution: TURN THE UNIT OFF and use the emergency heat setting at the thermostat to turn the back-up heat on to keep the home comfortable. A garden hose can be used to melt the ice build-up.
Your auxiliary heat, or secondary heat source, should come on when your heat pump is struggling to heat your home effectively. The thermostat will trigger auxiliary heat when: The outside temperature is below 40 degrees or a set aux heat trigger temperature. The heat pump is in defrost mode.
Lockout controls minimize use of strip heat, maximizing energy savings. Incorrect lockout settings result in the majority of inspection failures. PTCS Spec: Set auxiliary heat lockout to 35°F or lower.
As long as your house is properly air-sealed and insulated, an air-source heat pump can perform well beyond temperatures of -13 degrees Fahrenheit!
Increase your home's temperature by a couple degrees above your normal setting now, before the worst hits, and then leave your thermostat alone. Do not turn it back down at night. In this extreme cold, your heating system will struggle to return to where you originally had it set.
There are several reasons why your heat pump could be doing this. It could be that your heat pump unit is covered in ice or that it can't endure the freezing outdoor temperature. It could also be that your heat pump is struggling to turn on. Your heat pump not keeping up is an issue you need to resolve ASAP.
If freezing has already occurred, shut off the unit (keeping it on could damage the unit) and pour water over the unit to melt the ice (do NOT attempt breaking up ice with heavy tools!). In addition, check to make sure no damage has been done to the copper coolant lines, this might be a job for a professional plumber!
However, if you're leaving the room for more than a couple of hours, it's best to turn your system off. Keeping your heat pump on when it's not needed can lead to even higher power bills and cause your system to break down faster than it should.
Heat Pumps Don't Actually Stop Working
Contrary to popular belief, heat pumps don't ever stop working when it's cold. These systems are built to withstand frigid weather, operating at 100% efficiency even down to -13 degrees Fahrenheit.
This is where emergency heat comes in. Typically, this setting on your thermostat kicks on when the temperature is anywhere between 30 to 35 degrees Fahrenheit. How your emergency uses this air differs from the normal way that your heat pump usually functions.
This can cause concern, as auxiliary heat typically is not supposed to run all the time. While it's normal for auxiliary heat to kick in during exceedingly cold temperatures, running it too long may indicate an issue with the heat pump.
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.
Rebate-eligible heat pumps can reach over 400% efficiency in mild temperatures and can maintain well over 200% efficiency even into negative temperatures. This is why turning off a heat pump in frigid temperatures and opting to use a fossil fuel boiler or furnace instead is a mistake.
Heat pumps don't need to be set on max to work
If the day's particularly cold, a burst of higher temperature won't hurt. But we'd always suggest aiming for a regular setting around that 18-degree mark as this is generally considered comfortable room temperature.
Heat pumps operate most efficiently when holding a steady temperature. Turning heat pumps down when you're away or asleep may actually use more energy than leaving them on. The reason is that they have to work harder to come back to the desired temperature than they do to maintain it.
You should only manually switch to EMERGENCY HEAT mode if your heat pump is malfunctioning and you need to keep your house warm while waiting for repairs. In rare cases, such as during freezing rain, ice could build up on the compressor fan fins and potentially cause damage.
Air Filters
A dirty, clogged air filter hinders airflow, making it easier for ice to build up. Change your air filter on your heat pump regularly to prevent this.