Air-to-Water Heat Pumps

  • Central heating and hot water
  • Save on your energy bills
  • Reduce your carbon emissions
  • Government grants available
  • Your home must be well insulated
  • More attractive to homes off mains gas

Air-to-Water Heat Pumps let you use the heat in the outside air to provide central heating and hot water for your home. They can help you to save on your energy bills and reduce your carbon emissions. Grants and incentives are also offered by the government to encourage their uptake.

The typical installation is electrically powered and consists of linked outdoor and indoor units. These contain a refrigeration circuit  that absorbs heat from the outside air before amplifying and distributing it to your home’s central heating and hot water systems.


A key feature of an Air-to-Water Heat Pump is its ability to generate more energy to heat your home than is required to power its operation. Efficiencies of 300% can be observed with 1 kWh of electricity used to power the pump generating 3 kWh of energy to heat your home. Learn more about heat pumps.

Air-to-Water Heat Pumps are unlikely to be a good choice if your home is not well insulated. Good levels of roof, floor and wall insulation are all  desirable as are double glazed windows. Air-to-Water Heat Pumps also work better with low temperature central heating systems (e.g. oversized radiators).

Save on your energy bills

Installing an Air-to-Water Heat Pump can help you to reduce your monthly energy bills depending on your current system and the other alternatives available to you. Savings are more likely if you do not have access to mains gas. Savings are unlikely to be possible if your home is well insulated.

The table below identifies the savings that the Energy Savings Trust suggests might be made by replacing an existing heating system with an air source heat pump in an average detached 4 bedroom home. Find out more about these figures.

Existing System Saving per year RHI income per year*
Gas (Older non condensing) £295 to £425 £905 to £1,365
Electric (Older non condensing) £715 to £1,295 £905 to £1,365
Oil (Older non condensing) £360 to £555 £905 to £1,365
LPG (Older non condensing) £1,200 to £1,805 £905 to £1,365

Government grants*

Installing an Air-to-Water Heat Pump may qualify you for the government’s Domestic Renewable Heat Incentive scheme. Successful applicants to this scheme who have installed an Air-to-Water Heat Pump are eligible for a grant in the form of a series of payments over 7 years.

The Energy Savings Trust estimates these payments could be worth between £905-£1,365 per year.

[Last updated January 2016]