According to Energysavers.gov, heat pumps are the most efficient form of electric heating in moderate climates (like eastern North Carolina). And as Americans are spending almost half of their home energy costs on space heating, heat pumps can be a great way to save money.
Heat pumps work by transferring the heat from the air, ground, or water into your home. Even on a 32 degree day, enough heat can be drawn from the outside air to warm a home with a heat pump. What makes them so special is that they can actually reverse their cycle and cool your home as well by collecting the heat from inside your home and pushing it outside.
Heat Pump Cooling Cycle:
- Refrigerant arrives at the compressor as a cool, low pressure gas and leaves as a hot, high pressure gas and flows to the condensing coil (outdoor coil).
- In the outdoor coil, the heat from the refrigerant is released into the outside air via the outdoor fan. This process cools the refrigerant inside the outdoor coil and turn it into a liquid.
- The much cooler liquid refrigerant leaves the outdoor coil and passes through the thermal expansion valve (TXV) where the pressure and temperature of the refrigerant is lowered and sent to the evaporator coil (indoor coil).
- In the indoor coil, the liquid refrigerant evaporates absorbing heat from the return air. At the same time, moisture is removed from the air and is collected in a pan at the bottom of the coil and flows to a drain leading outside the home.
- The refrigerant leaves the indoor coil as a gas and is returned to the compressor to start the cycle over again.
Heat Pump Heating Cycle:
- The heating cycle is the reversal of the cooling cycle with one extra step: the defrost cycle.
- In the outdoor coil, the heat pump evaporates a low temperature refrigerant and as the liquid evaporates, it absorbs heat from the outside air. Heat pumps can do this because heat exists in all air down to absolute zero.
- After the gas refrigerant is compressed in the compressor it passes to the indoor coil and condenses. This releases heat to the inside.
- When it is below freezing outside, ice can build up on the outdoor coil. Too much ice can reduce the unit’s ability to provide the required heat. This is when the defrost cycle occurs to melt this ice.
- Units use a timer, thermostat, or a combination of the two to control when the system needs to go into defrost. During the defrost cycle, the system actually switches in to air conditioning which melts the ice build up. To keep from blowing cold air into your house, back up heat is provided by the heat strips.
Though heat pumps are great for milder winter climates like we see here, they are not very efficient for people who live in areas where it regularly drops below freezing. To make the most out of your heat pump, its best to have a programmable thermostat installed and have regular preventative maintenance performed semi-annually. Its also important to remember to replace air filters every 30 days or as needed.
If you would like a free estimate on having a new heat pump installed in your home, please give Davis Heating & AC a call anytime. We can help determine if a heat pump is right for you and your family. We serve Jacksonville and surrounding areas.