Air source heat pump installation in Chelmsford and Essex.

The air-to-water heat pumps we install take heat from the outdoor air, even when it feels cold outside. Electricity powers the compressor, which raises that heat to a useful temperature. The system transfers it to water circulating through your radiators or underfloor heating, and normally heats a separate cylinder for your hot water.

This is an air-to-water system. Air-to-air heat pumps, often used for warm-air heating and air conditioning, heat rooms directly rather than supplying central-heating water. The grant amounts on this page are for air-to-water systems, rather than air-to-air heating.

We calculate each room's heat loss: how much heat it needs to stay comfortable at the cold outdoor temperature used for winter sizing. That calculation considers the room, walls, windows, insulation and ventilation, so we can match the system to your home.

A boiler's kW rating may reflect rapid hot-water delivery rather than space heating. Bedroom count and an Energy Performance Certificate (EPC) provide context, but neither is enough for final sizing. An oversized heat pump can switch on and off too frequently; one that is too small may not keep the home warm in cold weather.

What we explain in your quote

Your quote sets out the proposed design and agreed scope, including any changes to your existing heating. We'll explain which of the following apply to your installation and what is included or excluded:

• The proposed unit and the heat demand it is designed to meet.
• The planned heating-water temperature and which radiators or underfloor heating circuits will be used in each room.
• A cylinder specification suited to the heat pump and household demand.
• The outdoor position, noise and planning checks, plus electrical work required.
• An itemised list of the work, including what needs changing and what is excluded.

Planning a self-build or development? Talk to Connor before first fix so we can plan these decisions around your build. Our new-build plumbing and heating service covers plumbing and heating throughout the build.

An air-to-water system normally needs storage for your hot water. If you currently have a combi boiler, we look for space for a cylinder and its pipework: the outdoor unit does not supply instant hot water in the same way as a combi.

We assess an existing cylinder before recommending whether it can stay. Its heat-transfer coil, which transfers heat from the heating circuit into stored water, must suit the heat pump. The amount of water it holds, how quickly it reheats after use and your showers or baths all affect the choice. We also check cupboard dimensions, access and maintenance space.

Depending on the design, an immersion heater may provide backup or help with periodic hot-water hygiene cycles. We show you how these controls work at handover and explain the safety arrangements. Speak to Connor before changing safety settings.

Connor is G3-qualified for unvented hot-water cylinder work. Our cylinder installation and servicing page explains what is involved in choosing, fitting and maintaining suitable hot-water storage.

The Boiler Upgrade Scheme offers £7,500 for an eligible air-to-water installation. Until March 2027, qualifying properties can receive an additional £1,500, making £9,000 in total, if the existing heating is oil or LPG and the property has no mains gas connection. Both fuel and gas-connection conditions must be met.

Other scheme conditions apply, including property ownership, the system being replaced and equipment standards. Hybrid systems retaining fossil-fuel heating alongside the heat pump are not eligible. Most developer new builds are excluded. Eligible self-builds may qualify, and some completed new builds with a fossil-fuel boiler may qualify for a replacement.

For the oil/LPG uplift, properties on heat networks and those with an existing mains gas meter are excluded, even if the meter is capped or clamped.

How the grant application works

If you're hoping to use the grant, mention this when you speak to Connor so eligibility and the application arrangements can be discussed alongside your installation. The scheme requires the application to be made by an MCS-certified installer.

Ofgem asks you to confirm your consent to the application. An approved grant is taken off the amount you pay and shown on the quote and invoice.

During the survey, we assess where your outdoor unit could go. The position needs the manufacturer's airflow clearances, model-specific safety space and maintenance access. We also consider the base, drainage for condensate and defrost water, vibration control and neighbouring living-room and bedroom windows and doors.

We consider noise and planning requirements alongside the position. Many installations can be permitted development, meaning no separate planning application is needed if all the relevant conditions are met. Listed buildings, conservation areas and properties with restricted permitted development rights need particular checks. Our assessment uses the current England requirements for your property, including the changes introduced in 2025.

The noise assessment predicts the sound near neighbouring habitable-room windows or doors, taking account of distance, reflecting surfaces and screening. The current sound limit used in this assessment is 37 dB, averaged over five minutes at the specified positions near those windows or doors. It is not a measurement taken beside the unit or a limit applied at every boundary.

Passing the noise calculation alone does not establish permitted development. Connor can discuss your available space and explain which planning checks apply, including whether local planning authority advice is needed.