What temperature does a heat pump quit working? 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! Some newer models can handle temps as low as -22 degrees.
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.
That brings us to the potential Achilles' Heel of heat pumps: they don't work as well in cold weather when you need them most. When the ambient temperature drops to 5 C (about 40 F) or lower, it can mess with the working fluids' ability to absorb and release heat by affecting its phase change or thermal properties.
Air source heat pumps work efficiently in heating and cooling modes, making them a versatile choice for year-round comfort. Unlike boilers or furnaces, which cycle on and off to maintain a comfortable temperature, heat pumps can run continuously without wasting energy.
Check the air filter of your unit to make sure it's not clogged or damaged. Replace it if it's dirty. Try to remove any ice that's built up on the top of your heat pump. Use a garden hose to melt the ice away instead of jabbing it with a sharp object; doing the latter may damage your unit.
The unit remains in the defrost cycle (or cooling cycle) until the thermostat on the bottom of the outdoor coil senses that the outdoor coil temperature has reached about 57° F. At that temperature, the outdoor coil should be free of frost.
A little frost on your heat pump is normal as the pump pulls warmth from the outside air and disperses it into your home. During this process, the coils are colder than the air surrounding them, causing condensation that freezes in the cool temperatures.
It states that the control for the lockout temperature shall have a maximum setting of 40 degrees F, and set for 32 degrees or less at final inspection.
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. Don't use emergency heat mode unless your heat pump stops heating your home altogether. If that happens, contact a professional heat pump repairman for help.
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.
Auixiliary Heat will turn on automatically when heat can no longer efficiently transfer heat from the outside air to heat pump. This is when the outside is around 35-40 degrees and the indoor temperature is around three degrees cooler than the thermostat setting.
Heat pumps are designed to work in all seasons and in all climates. Most efficient heat pumps, like Trane systems with their Climatuff™ Variable Speed Compressor, can handle temperatures as low as 0 degrees Fahrenheit for average-sized homes.
For this reason, heat pumps start to lose efficiency at around 40 degrees F and become less efficient than furnaces at around 25 degrees F. Heat pumps continue to be effective at cooling the indoors, even at high temperatures. In the South, it rarely gets below 25 degrees.
If the temperature is too low, ice may have gathered on the device. This obstructs airflow and prevents heat absorption. Usually, heat pumps have defrosters which help alleviate this problem. If the defrosters are active, this should be enough to fix the problem.
With a typical operation of a hybrid heating system, the heat pump will operate with ambient temperatures above 32 degrees. When temperatures are below 32 degrees, the gas furnace will operate.
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.
The heat pump emergency heat setting is used when your heat pump needs a break to avoid system damage. Plus, it works well at warming your home in below-freezing temperatures. The “em heat” setting on your thermostat indicates your emergency heat has been activated.
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.
The defrost cycle is activated when the temperature of the outdoor coil drops below 32 degrees. At this temperature, frost can form on the coil, which can cause damage if it builds up. This is where the defrost cycle comes in. Your heat pump will switch to cooling mode to warm up the coil and melt the ice.
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.
If there is not enough refrigerant in your system, it can't absorb as much heat. As a result, the coil may freeze if the outside temperature drops below 32 degrees Fahrenheit. Furthermore, as your heat pump naturally ices up in cold temperatures, there may not be adequate refrigerant to defrost the heat pump.
Use a garden hose to spray water over the frozen heat pump components and melt ice. Do not use tools or sharp objects in attempts to chip away ice from coils, as serious damage can be caused. Look for causes of excess ice on your heat pump. Check the air filter and replace it if it is dirty.
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.
When the filters get clogged, the heat pump gets dustier, which is where damage can result. The most obvious spot is on the evaporator coils, which excessive dust can serve as insulation between the refrigerant and the air it's trying to cool.