Keep your outdoor units clear.
Keep shrubs away from outdoor units and remove leaves that may become stuck in them, being careful not to bend the fins. Clear snow drifts away from outdoor units but don't worry about snow and ice accumulating on them. Heat pumps automatically defrost.
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.
When it's extremely cold outside, the temperature difference is large, which makes it harder for the heat pump to transfer heat effectively.
“Auto” mode could cause your heat pump to heat on a cool summer night or cool on a sunny fall or winter afternoon. To avoid accidentally cooling during the fall and winter, use “Heat” mode. Likewise, to avoid accidentally heating on a cool summer night, use “Cool,” “Dry,” or “Fan,” but not “Auto.”
Contrary to popular belief, air-source heat pumps work amazingly well in winter—even in very cold climates.
Once you understand how a heat pump operates, we can explore some possible reasons why a heat pump might blow cold air, such as incorrect thermostat settings, clogged air filters, a dirty outdoor unit, or issues with the reversing valve.
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.
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.
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.
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.
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!
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.
On the flip side, running a heat pump all day could lead to unnecessary energy use and higher costs, particularly if the house is empty for long periods or is well-insulated and doesn't require constant heating or cooling.
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.
If you aren't getting enough heat from your heat pump, you should check the outdoor unit first and foremost. Is the outside of the unit casing covered in ice? If so, you may have a broken defrost cycle. As the outdoor unit leeches heat from the air, it creates condensation that then freezes on the outside of the unit.
Based on our research, the best cold climate heat pump is Mitsubishi's Hyper-Heating, or H2i. Listed as Mitsubishi's M-Series or P-Series for home installation, these heat pumps maintain their full heating capacity down to 5F, and can produce useful heat down to -13F.
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.
If you're cold even though your thermostat indicates you shouldn't be, your furnace likely isn't the problem. In most cases, it's working just fine. It's your home that needs attention. Lack of insulation, severe air leakage, and/or unbalanced ductwork are frequently to blame.
Heat pumps are designed to run continuously. A good starting temperature to set is 68 degrees Fahrenheit.
For winter heating, aim for the lowest comfortable setting, around 68-70°F when occupied. Recommended configuration includes: Set the system to “heat” or “auto” and increase the temperature to 68-70°F during occupied hours. Program the thermostat to lower temperatures to around 62-65°F when away or asleep.
A heat pump can be more than 100% efficient because it is not generating heat but just moving it from one place to another. This means heat pumps, depending on outdoor conditions and on the heat pump design, can be anywhere from 200% to 400% efficient.
It's natural to think "AUTO" mode would be a more efficient setting. But if you use it, your unit runs the risk of toggling unnecessarily between heating and cooling. Your heat pump will run most efficiently when set to "HEAT" in winter and "COOL" in summer.