Knowledge is power. What do you know about your heat pump central heating and cooling system? Does it matter? Of course, it matters! It may be working fine at the moment, but there may be some things you don’t know about how your heat pump works. The more you know, the better off you are. Here’s two reasons: 1) You will know why it is essential to have regular maintenance done on your system, and 2) You will know how to maximize your energy utility costs. So GAMA Air is going to explain six things you may not know about your heat pump system.
- A heat pump system has the following two aspects: A air handler (fan coil) or ‘indoor unit’, and a compressor/condenser, or ‘outdoor unit’. In most cases the fan coil is inside your house. However, if you have a packaged system then everything is outside in one unit. (For simplicity we will use the terms ‘indoor unit’ and ‘outdoor unit’.)
- A heat pump uses refrigerant to warm your house. Electricity is the fuel for a heat pump, but the electricity is powering a process that uses refrigerant to transfer heat from outside to inside your home. “But wait”, you say, “How can the air outside on a cold winter day heat up my home?” Easy! Let me explain. The compressor in the ‘outdoor unit’ is like a pump that pushes hot refrigerant into the ‘indoor unit’. The hot refrigerant heats up the coil, which looks something like a car radiator. The fan in the ‘indoor unit’ pushes air from your house through the coil. The air pulls heat out of the coil and is blown into your house.
- A heat pump uses heat from outside to warm your house. The refrigerant leaving the coil of the ‘indoor unit’ is now cooler and goes out to where the compressor is. Then it passes a tiny nozzle and comes out as a mist into another radiator-like coil outside. This mist is very, very cold which means that even on a winter day there is enough heat in the air outside to heat up this mist. Now the refrigerant is a cool vapor so the ‘outdoor unit’ compresses the vapor into a hot liquid and pumps it into the ‘indoor unit’. And the cycle continues.
- A build-up of frost on the ‘outdoor unit’ is normal. The mist we mentioned that is passing through the outdoor coil is actually at sub-freezing temperatures. So if the air temperature outside is close to, or below, freezing then a coating of frost will gradually build up on the coil outside.
- The outdoor fan turning off while the compressor continues to run for a few minutes is normal. That frost has to be removed, so heat pumps are designed to go into a defrost cycle every hour or two. The defrost cycle reverses the flow of refrigerant, so for several minutes the coil in the ‘outdoor unit’ heats up and melts the frost while the coil of the ‘indoor unit’ gets cold.
- Heat pumps have back-up heaters. In order to keep the house from cooling down during the defrost cycle, the ‘indoor unit’ uses its electric heating elements. These are similar to what you see in your toaster, just much more powerful. During the several minutes of the defrost cycle these turn on so you don’t feel cold air blowing into your home. These also act as a back-up or auxiliary heat source by turning on if the temperature in your home falls 3 or 4 degrees below your set temperature.
If you have questions about your heat pump system and are eager to get a response, then you’re at the right place! Fill out the form on our “Ask an Expert” page, and the resident expert at GAMA Air will get back to you quickly with an answer.