Air Source Heat Pumps

How does an air source heat pump work?

An air source heat pump is placed outdoors at the side or back of a property. It takes heat from the air and boosts it to a higher temperature using a heat pump. The pump needs electricity to run, but it should use less electrical energy than the heat it produces. Take a look at the graphic below for a visual representation of how an air source heat pump operates.

The main type of air source heat pump (ASHP) used for central heating and hot water is an air-to-water pump. As the heat produced is cooler than that from a conventional boiler, you may need to install larger radiators or underfloor heating in your home to make the most of it. A technical survey is recommended to establish whether the existing radiators will be adequate. 

For more information you can obtain impartial advice from the Energy Savings Trust here.



The Renewable Heat Incentive gives financial support to people who use certain renewable technologies to heat their homes. The payments are meant to help offset the cost of installing and running your new heating system.

It is government-funded, by the Department for Business, Energy and Industrial Strategy, and aims to cut carbon emissions and help the UK meet its renewable energy targets. You apply to energy regulator Ofgem to join the scheme and it makes payments to you.

How do Renewable Heat Incentive (RHI) payments work?

After joining the RHI scheme, you receive a quarterly tariff payment for every kilowatt hour (kWh) of renewable heat you produce. The amount you will be paid per kWh of heat depends on the renewable technology you install, when you apply to receive RHI, and your home's EPC. Your payment amount will be estimated, based on your home's Energy Performance Certificate (EPC) rating.

ASHP Heat Loss Calculation Service

Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. You may require larger radiators in some or all of your rooms. You might also consider underfloor heating. 

If you are installing an ASHP to replace a gas or oil boiler, you should consider whether you should upgrade your insulation to get the most out of your ASHP. You can not claim the Renewable Heat Incentive if you do not have adequate wall or loft insulation.

Stage 1: Pre-Site Visit Survey

Pre Survey – A desktop qualification and estimation of required heat pump size, projected customer RHI Returns / Fuel Savings – (we can do this if there is an existing EPC and/or are provided with some basic customer information) – we will identify any issues prior to you instructing a full tech survey (i.e. planning constraints, insulation issues).


Stage 2: Energy Performance Certificate

An Energy Performance Certificate (EPC) which will be lodged and eligible for RHI Applications. An EPC dated within 2 years of the Heat Pump commissioning date is required for all RHI applications. An existing EPC from the register may be used providing that there have been no upgrades or alterations to the property since it was produced.


Stage 3: Technical Survey

Full Air Source Heat Pump Survey. Full set of photos and videos, detailed floorplans, window and radiator information. All the data needed for full heat loss calculations and system design.


Stage 4: Heat Loss Calculations

Full room by room heat loss calculations, includes heat pump system sizing, cylinder sizing, radiator change recommendations etc. ready for an installation company to use. (Only available once Stage 3 has been completed).

If you are considering an air source heat pump for your own home or are a heat pump installer looking for heat loss calculation services please contact us below for prices.