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Air source heat pumps

With air source heat pump technology the heat pump technology the heat is extracted from the surrounding air.

It is possible to extract considerable heat from the air at temperatures as low as minus 15°C.This heat is then passed via the heat exchanger into water and is used to provide space heating, typically via underfloor heating systems. The technology can also be used for water heating and, in some cases, cooling. Air source heat pumps supply more energy than they consume; the heat energy released can be up to four times the energy required to power the equipment.

Installations costs/payback

The capital cost is high, and they are costly to install (though they are cheaper than ground source heat pumps). A typical installation will cost around £8,000*.
They work best with underfloor heating systems, which will be costly (especially for retrofit applications), and low temperature radiators.
Installations in older buildings can be quite costly because of the insulation required. Many older buildings can never be made suitably efficient to use an underfloor heating system or low temperature radiators.

Running costs

Running costs are relatively low all you pay for is the machine to recover the heat and the cost of the energy to run the machine and circulate the refrigerant contained in the system.
Typical running costs would be around £580 per annum*.

Carbon emissions / the environment

Heat pumps are efficient and release relatively low carbon emissions.
The amount of energy consumed to operate the pump is much less than would be required to heat the building by conventional means.
In colder conditions carbon emissions rise steeply.
As with Ground Source Heat pumps the units contain refrigerants. These are normally HFC’s (Hydrofluorocarbons) which are extremely powerful greenhouse gases. As such they will need to be maintained by a specialist engineer.

Features and benefits

Air source heat pumps need less space than ground source heat pumps.
They are safe and reliable.
They can provide cooling.
Air source heat pumps can be fitted outside a house or in the roof space.
They are suitable for both new build and retrofit applications.
This well-proven technology has been in use for decades and heat pumps are used all over the world.
Air is limitless, and free,
Air is clean and pollution-free.

Potential drawbacks

They require an electricity supply to pump the heat, so property owners will still be relying on a conventional energy source.
Three phase electricity may be required.
They perform better with warm air temperatures – which could be an issue in the colder months.
Air source heat pumps are efficient at producing low-grade heat which means they are ideal for underfloor heating. If asked to raise the temperature of water above 35°C, air source heat pumps become much less efficient and there is the risk of legionella if high water temperature (at least 65°C) is not achieved. It is therefore standard practice to put in an additional water heating system for sanitary water. LPG is a very effective fuel source of this system, and can also satisfy your cooking requirement and provide feature fires.
Buildings must be well insulated to gain maximum benefit.

Sources