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Energy is absorbed by the earth from the sun throughout the year and stored in large quantities. The air at the surface then absorbs this solar energy from the ground.
As the energy in the air is constantly being replenished, it provides a constant, renewable energy source that an air-to-water heat pump can use to heat a building

How do air source heat pumps work?
An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can extract heat from the air even when the
outside temperature is below as minus -0° C.

There are two principal locations in the transfer of heat; the place where heat is absorbed, (the source), and where it is injected or pumped, (the destination). We see that all a heat pump is really doing is moving heat energy from one body of air to another body of liquid.

The purpose of the air source heat pump is to absorb stored energy from the air outside your property - A large volume of air is pumped through one side of the heat pump while a small volume of water is heated as it passes through the other.
I.e. - 10 litres of air cooled by 4 degrees = 1 litre of water heated by 40 degrees. This is an oversimplification of the process but from this example you can see that by cooling a large body of air by a few degrees, it is possible to heat a small body of water. This is the main principal behind an air source heat pump.

The benefits of air source heat pumps

• Reduce your fuel bills: air source heat pumps run on electricity, so there's no need to pay for gas, oil or solid fuels to heat your home.
• Cut down on wasted electricity: heating your home with an air source heat pump is much more efficient than using electric radiators.
• Save space: an air source heat pump system is compact, and requires no storage space for fuel.

Is an air source heat pump suitable for my home?

To tell if an air source heat pump is right for you, there are a few key questions to consider:
• Do you have somewhere to put it? You'll need a place outside your house where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good flow of air. - This external unit is connected by refrigerant pipes to an internal unit about the size of a gas boiler housing or undercounter fridge
- from this point the return and flow pipework to your existing central heating system & hot water storage is connected. A number of other combination systems can be installed to retro fit a heat pump to assist other technologies or primary or secondary fuel / heating sources.

Is your home well insulated? Since air source heat pumps are finely balanced to save on energy and use less than traditional boilers, it's essential that your home is
insulated and draught proofed well for the heating system to be effective.
• What fuel will you be replacing? The system will pay for itself much more quickly if it's replacing an electricity, Liquid Petroleum Gas (LPG) or coal heating system.

• What type of heating system do you want? Air source heat pumps are suitable for powering both underfloor heating systems or warm air heating or wall mounted radiator systems.
• Is the system intended for a new development? Combining the installation with other building work can reduce the cost of installing the system.

Very simply:

When something evaporates, heat is taken in e.g.
• You feel cold when you get out of a swimming pool. The water evaporating off your skin takes extra heat from your body and makes you feel cold even though the
pool hall is hotter than a normal room.
When something condenses, heat is given out e.g.
• When you get steam from a kettle on your hand, it burns so badly. The steam condenses on your hand and gives out extra heat.
These two processes are the foundation of refrigeration and heat pump technologies.

The above diagram shows the refrigeration cycle inside a Waterkotte heat pump. Instead of water however, the heat pump uses a refrigerant gas with a very low boiling point (-40 deg. C and lower, depending on the refrigerant used). This allows it to evaporate very easily at low temperatures.

The refrigeration cycle is made up of 4 steps:

1) The refrigerant is allowed to evaporate in the evaporator. This draws heat from the heat source water into the refrigerant.
2) The refrigerant is compressed using a mechanical motor. This increases the energy per unit volume and allows the heat pump to produce higher output temperatures. This is the largest electrical input into the heat pump.
3) The compressed gas is allowed to condense in a condenser. This gives out the heat to the heating water. The more compressed the gas, the higher temperatures can be reached.
4) The gas is allowed to uncompress as it goes through an expansion valve and the cycle starts again To achieve maximum efficiency, the temperature of the heat source must be as high as possible and the flow temperature on the heating side must be as low as possible. In this way the compressor will not have to compress the refrigerant gas as much and less electricity will be used. This again highlights the importance of the design of the air source system and the heat distribution system.
The efficiency of air source heat pump systems is measured by a coefficient of performance (CoP) - the amount of heat they produce compared to the amount of electricity needed to run them. A typical CoP for an air source heat pump from The Solar Panel People is around 3.5. upwards.

A COP of 7 can be provided by some models of our heat pumps when both the cooling and heating cycles are in operation. This fact makes heat pumps an ideal choice for commercial buildings with proven savings to your businesses overheads. Talk to our commercial sales & technical advisor 'Mike Fleming' for an in depth survey for your commercial premises or industrial building. Our engineering and design team can provide site specific data based on your heating and cooling (HVAC) building needs. We can consult with your architect / QS and other design professionals for both new buildings and retro fit solutions.

Commercial Heat Pump & Air conditioning - HVAC design