Air-to-air heat pumps and hot water: what actually happens to your boiler

The full-removal rule

The Boiler Upgrade Scheme requires the new system to replace the existing fossil-fuel or electric heating system, but it does not require every existing component to be removed. A fossil-fuel boiler cannot remain as part of a BUS-funded heat-pump system; non-fossil supplementary appliances and suitable existing components may be retained.

That leaves an important question: how will the new system meet your hot-water needs?

Why air-to-air needs a hot-water plan

Most air-to-air heat pumps move heat between the outside air and the air in your rooms. MCS design standards also contemplate air-to-air designs that provide a proportion of domestic hot water, so an installer must explain what the proposed system will provide.

For a Boiler Upgrade Scheme installation, the heat pump must meet the property's full space-heating demand and the combined system must meet its full space-heating and hot-water demand. A fossil-fuel boiler cannot remain as part of that system.

The options installers use for hot water

An installer must design the combined system so that it can meet the property's full space-heating and hot-water needs. The appropriate hot-water arrangement depends on the property and must not retain fossil-fuel heating as a supplementary appliance.

What to ask in your survey

Ask your installer to spell out: which hot-water option they are proposing, the running-cost estimate on your electricity tariff, where the new equipment goes, and which existing components can be retained or must be removed.