Removing a hot water cylinder when switching to a combi boiler under ECO4: what to know (guide 2026)

Guide by ApplyFreeBoiler.uk (Reliant Energy Solutions Ltd), a heating and insulation installer in Bury, Greater Manchester. We are not the government, Ofgem or an energy supplier.

If your home has a hot water cylinder and tanks in the loft, and your new boiler under ECO4 is a combi, those parts may no longer be needed. This page explains what households commonly ask. It is general information from ApplyFreeBoiler.uk, a heating and insulation installer in Bury. Your installer will confirm what suits your home. This page does not guarantee funding.

1. Is a combi right for your home?

A combi heats water on demand, so it can suit smaller households. Homes with several bathrooms in use at once may suit a system boiler better. Ask your surveyor.

2. What happens to the cylinder

Ask whether the cylinder will be removed or capped off and left, and who takes it away.

3. Loft tanks

Cold water and expansion tanks in the loft may also become redundant. Ask whether they will be drained, removed or left in place.

4. The airing cupboard

Removing a cylinder can free up a cupboard, but you may lose a warm space for drying clothes. Think about how you use it.

5. Immersion heater and electrics

If the cylinder had an immersion heater, ask how its wiring will be made safe.

6. Water pressure and flow

A combi depends on your mains water pressure and flow. Your installer may check these before deciding.

7. Making good

Ask what making good is included where pipes are removed or the cupboard is opened up.

8. Check funding and local figures

See ECO measures by council on ApplyFreeBoiler.uk, built from DESNZ Household Energy Efficiency statistics, to see how many ECO measures have been installed in your local authority area. Use the ApplyFreeBoiler.uk eligibility check to see whether an ECO4 heating or insulation pathway may be available for your home in England, Scotland or Wales. ECO4 is due to close on 31 December 2026.