WHAT IS A HEATPUMP?
Pretty well every house has a type of heat pump. Your fridge and freezer are both essentially heat pumps. In simple terms heat energy is collected from one place (the inside of your fridge and freezer) and transferred to the back or outside of the fridge using a cycle of compressing and evaporating a special gas.
A heat pump does the same but collects energy from outside air, the ground, water in a lake or underground and uses it to heat air or water to heat radiators or underfloor heating.
Why would someone want a heat pump?
Basically a heat pump uses electricity very efficiently to produce heating or hot water. It will generally be around 4 times better than using a standard electric heater.
How does a heat pump work and what makes so efficient?
The heat pump, unlike a simple electric heater, does not just convert electrical energy into heat energy, instead it uses the electrical energy to drive a compressor which uses a special sealed gas circuit (the gas goes round and round within the system) to collect heat energy from outside of the house (either from the air, water or the ground) it then converts it into useful heat which can warm radiators or under floor heating.
Surely when the weather is really cold there is no energy to collect?
Even when we as humans think it is cold in physical terms there is still plenty of heat energy its just not warm to us. The biggest problem is trying to collect it at below 0 as we start to get ice forming which insulates our collectors. Therefore our collectors must be defrosted when they ice or better still designed so they don’t freeze at all.
Ground source heat pumps generally have very large collectors which are so big they cannot freeze, the ground simply replaces the energy removed faster than it is extracted. Air source heat pumps will cope with low ambient air. The collector will then start to ice up, sensors carefully monitor the ice and look at the efficiency of the heat pump and when needed the heat pump will reverse and heat the collector to clear the ice within a few minutes and then resume its heat cycle once clear.
Water source heat pumps are generally designed not to extract too much heat and freeze or to shut off if this happens. Some systems use indirect collectors filled with anti freeze.
So as you can see ice is our biggest issue not the actual temperature, however the warmer the collector is the higher the efficiency.
What is the best type of heat pump ground , air or water source?
Each one has its advantages and disadvantages. There is no clear winner. One sort will normally just be right for your application.
Air source becomes less efficient as it gets colder, and the collector has to be defrosted in very cold weather, however it is cheaper and easier to install and does not take up much room. Air source heat pumps have become very effective over the last few years as the gas technology has progressed.
Ground source heat pumps will, if the collector is designed and installed correctly, maintain a constant efficiency regardless of air temperature but requires a large ground area and longer more expensive installation.
Water source needs a lake, river or bore hole. Bore holes can be expensive to produce but take less ground area and offer constant high efficiency.
Is a heat pump the best heating solution? Why might one be good for me?
Sometimes a heat pump may not be the best solution. If you live in a small house or flat and need to replace your existing boiler. You may not have a suitable outside place for the air collector or any option for the other collectors. Also a heat pump will not produce water for the radiators at a high enough temperature without upgrading the existing radiators.
Considerations regarding mains power supply size may also need to be taken into account.
Ideal situations for heat pumps are where there are no piped gas or a new build where under floor heating or low temperature radiators can be used. Under floor heating requires lower temperature water, which is ideal for heat pumps and makes the system even more efficient.
As a heat pump runs on electricity it eradicates the need for delivered gas and oil and is considerably cheaper than fossil fuels (whilst not so great heat pumps still offer savings over piped town gas)
Can heat pumps be used with other renewable energy systems or conventional heating?
Yes some people choose to heat their water using solar panels or even gas boilers to back up or heat other areas. Control systems can be used to automatically manage these.
I have been told that heat pumps don’t really work or have been told they just freeze
the ground -
There is no question if heat pumps work -