Heatpump Need to Knows......
Heat pumps are the most energy efficient heaters. See the diagram from the energywise website that compares heating costs.
Heatpumps have to be used wisely or they will cost more to run. Here are some tips to keep warm but keep the power bill down.
Set the temperature to a comfortable temperature (eg 18 – 21 degrees). If you set it on 30 degrees and walk around in a tee shirt and shorts then the heatpump will be working flat out to reach that temperature (which it may never reach) and it will use a lot of power.
Use the “Heating” function and not the “Auto” function. If set on heating and at 18 degrees then the heat pump will heat until that temperature and then it will stop heating (it will start heating again when the room temperature drops). If it is set on Auto and 18 degrees then it will heat until 18 degrees the stop. If the room heats more (eg because the sun comes out) then the heat pump will go into cooling mode and cool the room down to 18 degrees.
Don’t leave the heat pump on when you are not home. There is a lot of evidence showing that keeping a heat pump on all the time to keep the temperature up will actually use more energy than only using the heatpump to heat the area when you are using the area. So don’t leave the heat pump on when you are out of the house or overnight.
Heat pumps will stop working for a few minutes in cold weather. This is normal. When the heatpump is in heating mode and the outside temperature is really cold, the outside unit will eventually freeze up. The heatpump will then reverse the cycle for a while until the outside unit has thawed out and then it will start heating inside again.
So how does a heatpump actually work? Well firstly no air actually enters or leaves your room (many people believe it does). Heatpumps use a latent heat process to either heat or cool your room. This means that between the inside unit and the outside unit there is a closed loop of refrigerant with a compressor and a pump (similar to your refrigerator). Depending on whether your heat pump (called an air conditioner in other countries) is in heating mode or cooling mode depends on where the refrigerant is changing state from a liquid to a gas, or a gas to a liquid (at the inside unit or at the outside unit).
We all know from high school science classes that when you change a materials state you either give off or collect heat. The heat transfer happens at fins in the inside or outside unit. A fan blows air across these fins and the heat is transferred to the air. When you change a heat pump from Heating to Cooling you are just changing the direction that the refrigerant is moving between the inside and outside unit.
This is why they are so energy efficient as the electricity does not power a heating element. It simply operates a pump, a compressor, fans and some controls. If you are a science person and you want to know more have a look at this diagram.