Heat pumps are very clever devices. Rather than using electricity to heat the air directly, they use it to move heat from one place to another. This means that they are very efficient, typically producing the equivalent of 3-4 units of electrical resistive heating for every unit of electricity used.
Used as heaters, they collect the small amount of heat energy in large volumes of outside air and use it to heat your indoor air. They work on exactly the same principle as a refrigerator, and use very similar technology to work.
'Geothermal' heat pumps collect heat from a network of pipes laid just below your soil surface. These are even more efficient and are particularly beneficial when outside air temperatures are often below freezing. As this is rarely the case in Christchurch, the extra cost and inconvenience of installation is seldom justifiable. Modern heat pumps will work well until the air temperature drops well below -10c.
There is a lot of debate as to the best way to use a heat pump. This is mainly around whether it is best to leave them on at night or not. This depends on your circumstances:
Well insulated homes cost very little to keep warm, but cost nearly as much as poorly insulated homes to get warm (the same amount of stuff has to be heated)
There is a lot to be said for leaving a heater on as it keeps all your belongings warm. (see our general article on heating)
If you are out all day, and don't mind cold feet in the morning, you can save a lot of money by turning it off at night and setting it to come on an hour or two before you get home.
There have been a large number of studies that show that heat pumps are the cheapest form of heating unless you have ready access to free firewood.
A lot of people make some simple heat pump errors that cost them a lot of money:
1. Automatic.
It is tempting to leave the heat pump on automatic as this seems easy, especially if you are not familiar with them. Don't. This setting means that it will try to keep your room at the set temperature, heating or cooling as required. If you also have another heat source (say, the sun during the day or a log fire) you will find the heat pump trying to cool you down - opening a window is a much cheaper way to do that (or build a smaller fire!)
2. Fiddling with the thermostat
Thermostats save you money. Don't play with it. If your room is cold, setting the heat pump to a higher temperature will not make it feel any warmer any faster (well, not noticeably) but it will make your room too hot eventually. The machine can only heat so much and this cannot be changed. If you find yourself feeling the need to do this often, set your heat pump to come on earlier, or leave it on for longer.
3. Switching on and off.
See 2 - this is a common mistake. It leads to inefficient running and a room that cycles between too hot and too cold. Leave the thermostat on a sensible temperature. For a living room: 20 is cool, 21 cosy and 22 hot. For a bedroom 16 is minimum, 18 sensible and 20 too hot for most people to sleep comfortably.
4. Leave on during the holidays.
Unless you live in a frost prone or damp area, this is just a waste of money. If you will be away for a few days, let the house cool down.
5. Wrong Setting.
Especially for the elderly, the sunshine and snowflake icons that depict heating and cooling respectively can be hard to make out. If you have older friends or relatives, check that they can tell the difference. Consider using a permanent marker or sticky label on the control unit to help identify the correct setting.
6. Fear of Technology.
It is surprising how many people don't know how to use their heat pumps and so they use less efficient heating as a result. If you need help, our nurses are happy to assist registered patients with inquiries. We may even be able to visit to help you set it up properly.