On a cold night, you finally turn on your heat pump to warm up your abode only to discover the appliance is not working properly. Like any other machine, heat pumps can break down for any number of reasons. Here are two that may be causing the issue and what can be done to fix the problem.
The Appliance is Literally Frozen
Air-source heat pumps work like reverse air conditioners. In fact, most can perform double duty as heaters and air conditioners. They pull in outside air, cool it using refrigerant and discharge the heat generated by the process into the home instead of outside like A/C units usually do. Because of this, heat pumps tend to be window units, which subjects at least part of the machine to freezing cold temperatures.
This can result in parts of the appliance literally freezing. Ice may have formed on the exposed areas of the heat pump, something that will prompt the appliance to go into defrost mode and result in less heat going into the home. Alternatively, the unit may not be entering defrost mode, which may result in components not working properly (e.g. the fan may be stuck in place by ice).
The refrigerant can also cause issues in this area. If there is a leak, the refrigerant may freeze coils and other interior parts, which may lead to malfunctions.
Inspect your appliance. If you notice ice forming on it, carefully melt it using water. Absolutely do not chip at the ice because you could damage the unit itself. If the appliance works just fine after you clean it up, then you'll want to check that the defrost mechanism is working properly; otherwise, you may end up in the same situation.
If your heat pump still doesn't put out enough heat after you've removed the ice, however, you may have a refrigerant leak issue. You can confirm this if you open the machine and find ice on coils or you smell ether whenever the machine runs. Refrigerant leaks are best repaired by a professional, especially since the refrigerant will have to also be refilled once the machine has been fixed. Therefore, contact an HVAC company you trust to perform heating maintenance services.
The Heat Pump is Too Small
Another reason why your heat pump may not be warming up your home as expected is because it's undersized. This can happen if you've made changes to the home since you purchased your heat pump (e.g. enlarged a room). If the space is too big for the appliance, the heat pump will struggle to keep the area warm. It may remain on for extra long periods of time or the space may never seem to reach the desired temperature, and the colder it gets outside the worse the problem is inside.
A one-ton heat pump can accommodate up to 650 square feet. Your owner's manual should tell you how many tons your heat pump is. However, you can also figure it out by looking at the model number. There should be a number appended that's can be divided by 12 (e.g. 24, 36, 48). Divide that number by 12 to get the amount of tons the heat pump produces, then multiple the result by 650 square feet to get the approximate size of the space it can efficiently heat. If your space is larger than that number, then you probably should consider upgrading the appliance to a bigger model or sectioning of the space in some way (e.g. close doors to unused rooms).
For help determining what else could be causing your heat pump problems, call an HVAC company in your area.