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Air source heat pump installations

17 Oct 22 We are always getting asked the same question regarding ASHP's, the performance specification and how do they operate in cold conditions. Well, below is an in-depth overview....

What Is An ASHP?

Air source heat pumps are a remarkably clean and efficient source of producing heating and hot water for domestic and commercial properties.

Chase Renewables are experts in Heat Pump cost-effective low carbon technology. You can rest assured you have the backing of an excellent team of engineers who will guide and support you through your renewable journey and beyond.

We only install MCS accredited products to ensure our customers are able to claim available Government grants like the Boiler Upgrade Scheme Grant (BUS) payments in full.

How Does ASHP Work?

An Air Source Heat Pump looks aesthetically similar to an air conditioning unit, but in fact uses a highly efficient refrigeration cycle to extract energy from the external surrounding air.

The surrounding air; transferring energy from the latent air outside, into water to power your central heating and hot water supply.

Heat is collected using a fan to direct the flow of air over a copper coil containing a refrigerant.

Energy is transferred into the gaseous refrigerant inside the heat exchanger, which then flows into an electrically driven compressor, this gas is then compressed.

The heat from this vapour is finally passed through a heat exchanger, heating up the water in your hot water cylinder, which is then distributed either by underfloor heating or oversized radiators.

With this technology a correctly sized air source heat pump can work down to around -15˚C ambient air temperature, which is more than sufficient for mid-winter UK temperatures.

ASHP Benefits

Installing an ASHP will provide a range of benefits for your home or business

 Low Energy Costs

 Great Investment

 Lower your carbon footprint

 High Reliability

 Low Maintenance

 No Fuel Storage Needed

 Eligible For Grants and Incentives

 Easier to install than GSHP

 Some systems that provide additional summer cooling


Air Source Heat Pump Types

We offer two types of system, either a ‘Monobloc’ or a separate external condenser and internal compressor unit, called a ‘Split’ Unit System.

If internal space is tight the Monobloc accommodates some of the large elements of plant outside. These units heat water and circulate this into the building, and, because of this they must be located within 6m of the house to prevent excessive heat loss from the pipework between the unit and the house.

If you can accommodate an internal compressor unit you will have around 30m to play with, because the connections between internal and external are cold refrigerant lines so don’t lose heat.


When installing an ASHP the best system to pair this up with is underfloor heating for reasons of efficiency. This doesn’t preclude radiators in a few rooms, first floor bedrooms for example. These radiators will be two to three times larger those typically connected to a fossil fuel boiler and will have a low surface temperature. Chase Renewables will provide you with a full list of equipment required along with a specification and dimensions of each part required for the installation.


This depends around the location of the external ASHP unit. The further away from the property, the less you will hear the unit when in operation. All heating products make some noise, but heat pumps are usually quieter than fossil fuel boilers. An air source heat pump will output 40 to 60 decibels, but this depends on manufacturers equipment.

In the daytime, this should not be an issue but if you live somewhere rural and want your heating on overnight this may be something you need to get used to. The noise from an ASHP is directional, so think about where you’re going to put it carefully, and before buying visit an installation if possible.

Location & Planning

An Air Source Heat Pump requires good air flow in order to operate at its most efficient. Air source heat pumps (ASHP) are suitable for a wide range of property sizes and require little space. A large percentage of ASHP installations will fall under Permitted Development, but the fact that ASHPs do generate some noise means that their location can be an issue, sometimes requiring Planning Permission.

Planning permission may be required if your home is a listed building and for homes in conservation areas or World Heritage Sites, the pump should be installed at ground level

Due diligence to be checked before going ahead with the installation, just in case permission is needed prior.

Keeping all of the above in mind, there are limited places where you can put your Air Source Heat Pump. Generally, any outside wall on your house can be suitable as long as there’s enough space for the pump to take in air and you’re not breaching any local planning or building regulations, this may also include noise output (dB(A)) of the unit.

The pump should also be installed in a location it is easy to access for future servicing and maintenance purposes. You will need to refer the manufacturers literature for guidance; however, a rule of thumb would suggest 1m distance (min) from the face of the unit to any adjacent boundary, leaving 300mm from back of the pump to the structure.


Heat pumps should be selected as closely as possible to the design heat demands of the property. While we can’t control the outdoor source temperature, it’s possible to design ashp systems that use low temperature water indoors, meaning the heat pump can use less electricity and still heat your property comfortably. By using radiators with a larger surface area, or underfloor heating, more heat can be delivered into the room without increasing the water temperature.

Our aim of a well-designed system is to reduce the heating water the more efficient the heat pump will be, and therefore lowering the running costs.

Chase Renewables offer accurate heat loss calculation for final design and selection of the equipment. Certain elements are required to calculate heat loss through the various elements of the property, such as walls, roof, windows, floor finishes, ventilation then aggregated together. Our computer aided heat pump section package produces the correctly sized (kw) unit for the project.

It is essential that a heat pump is selected to achieve the desired output for the design conditions

How efficient are heat pumps?

Heat pumps are more efficient than other heating systems because the amount of heat they produce is more than the amount of electricity they use. The amount of heat produced for every unit of electricity used is known as the Coefficient of Performance (CoP). The Seasonal Coefficient of Performance (SCoP) or Seasonal Performance Factor (SPF) is used to show the efficiency of the heat pump across the whole year.

How much does an air source heat pump cost?

The cost of an air source heat pump varies depending on the size of heat pump, the size of the property, whether it’s a newbuild or an existing property, as well as whether you need to change the way you distribute heat around your property. You also need o ensure the property is well insulated throughout to obtain best results and retain heat within the property.

Get in touch with one of our renewable heating advisors today and request a free no-obligation quotation.

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