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.
Auxiliary heating turns on automatically to help heat your home more quickly if the temperature drops suddenly. Heat pumps require a supplemental heating source. This is especially critical when the temperature drops below 40 degrees Fahrenheit.
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.
Air source heat pumps typically work in temperatures of between -4°F (-20°C) and 68°F (20°C).
When Do Heat Strips Turn On? In general, if the outdoor temperature falls under 32 degrees Fahrenheit, heat strips are used. Heat strips can be utilized for backup or emergency heat; you can switch between the two. In the first case, the heat pump and strip will work simultaneously.
At What Temperature Does Heat Tape Turn On? Self-regulating heat tape typically kicks in when the surrounding temperature drops to around 38°F (3°C) to 40°F (4°C). As temperatures decrease, the heat output increases, and vice versa. Constant wattage heat tape relies on a thermostat for activation and deactivation.
You May Not Need an Electric Heat Strip If…
You have a cold-climate heat pump: Standard heat pumps are mostly used in warm climates that rely primarily on air conditioning. However, advances in heat pump technology now make it possible to heat homes more efficiently in northern climes.
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.
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.
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.
Auxiliary Heat – This is the secondary heat source that turns on automatically. Emergency Heat – This is when you turn on the secondary heat source.
Some heat pumps lose efficiency when outdoor temperatures dip below 32°F, but they won't completely stop working. Like other heating systems, a heat pump's efficiency depends on your thermostat settings. If you want to keep your home toasty during sub-zero temperatures, you'll lose performance capabilities.
The heater might blow cold air rather than warm if the gas line supply has been turned off. This usually happens when something goes wrong with the heater, and it breaks. For example, maybe there was a problem with a gas valve, the gas supply pipe, or something else in your furnace broke down.
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.
Aux Heat Will Not Turn On
One of the most common causes of a heat pump system or auxiliary heat not turning on is a blown fuse or tripped circuit breaker. Start by checking your fuse box or circuit breakers.
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.
Your heat pump will still work below freezing and below 15 degrees. It will continue to perform below 0 degrees or colder. It just won't be as efficient over those very coldest days of winter as using a gas-fired furnace.
It's normal for your heat pump to run fairly constantly in the winter time. With low temperatures, your pump will be working nonstop for hours to ensure your home stays warm. But if your heat pump is working overtime in the spring or summer when temperatures are milder, you may have an issue!
According to the Department of Energy, 68°F is the sweet spot that balances comfort and energy efficiency during the fall and winter months. When your home is occupied and when family members are awake, a heat pump setting of 68°F keeps the living areas reasonably warm.
On average, an air-source heat pump uses anywhere from 545 watts to 7,500 watts of electricity. The wattage per hour can be calculated by dividing the British Thermal Units (BTUs) needed to heat or cool your home by the SEER for warm months and the Heating Seasonal Performance Factor (HSPF) for cold months.
Know your temperatures
There is a middle point that'll help you with both. Set your heat pump temperature to 18 degrees or above to help fight damp and mould, but below 21 degrees to save on power. The higher the temperature, the more energy the heat pump will use, so anywhere between 18 and 21 is the sweet spot.
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.
Some heat pumps are designed operate independently without back up heating, while others are designed to use a back up heating system. Whether or not you need a backup heat source for your heat pump will depend on the type of heat pump you purchase, your climate zone, and the design and efficiency of your home.
Depending on your heat pump system, auxiliary and emergency heat can cost about 2-5 times as much as running normal heat. Though it's necessary for a heat pump to operate with auxiliary heat at times, you can take steps to reduce how frequently it's automatically used. Keep your thermostat set at 68 degrees.