Sources: Ofgem, ECO4 Guidance: Delivery v4.0 (26 Mar 2026), paras 5.186-5.203. Checked 31 October 2026.
The one-radiator rule
Ofgem says it does not consider a home with one radiator connected to a heating appliance (kept for health and safety reasons) to have a central heating system. So homes with gas back boilers and range cooker boilers with one radiator are considered eligible for first time central heating where the other eligibility rules are met. Its list of heating that may point to first time central heating eligibility includes:
- a gas fire with back boiler with one or no heat emitter;
- a range cooker boiler with one or no heat emitter;
- a solid fossil fuel fire with back boiler;
- gas, electric, oil or solid-fuel room heaters, and inefficient storage heaters;
- a warm air system, or no heating at all.
What first time central heating means
Ofgem defines first time central heating as installing a wet central heating system (radiators fed by a boiler or other heat source) in a home that has never had one, and that has not had a working or economically repairable efficient electric storage heater since 1 April 2022. The owner or landlord signs a declaration to that effect. First time central heating is outside the cap on broken boiler replacements, and the heat source can be, for example, a condensing gas boiler.
| Your back boiler | Likely ECO4 route |
|---|---|
| Heats one radiator or none | First time central heating (if the household and home qualify) |
| Runs several radiators, non-condensing | Upgrade of an inefficient boiler |
| Runs several radiators and is broken | Upgrade (if non-condensing) under the boiler rules |
Insulation preconditions
First time central heating has the strictest insulation precondition: even Band D homes getting it must have all exterior cavity walls and the loft or roof insulated (in the project, already done, or exempt). Expect insulation to be part of the job.
Who qualifies
The household test is the same as for all of ECO4: a qualifying benefit, or a council ECO4 Flex referral (income under £31,000, two proxies, or an NHS medical referral). The home must meet the EPC rule (D to G owned, or E to G owned on the Flex proxy route; E to G rented). Check with the ECO4 eligibility rules or the checker on this page.
Before you contact anyone
- Count the radiators the back boiler feeds.
- Note the fuel (gas, coal, wood) and roughly how old it is.
- Check your EPC band and what insulation you have.
- Contact an obligated supplier or your council, and ask specifically about first time central heating.
Questions
Can ECO4 replace a back boiler?
A gas back boiler or range cooker boiler with one or no radiator counts as no central heating in Ofgem's ECO4 guidance, so the home may be eligible for first time central heating if the household qualifies.
What if my back boiler runs several radiators?
Then the home already has a wet central heating system, so first time central heating does not apply. A non-condensing back boiler may instead be eligible for an upgrade, subject to the other rules.
Is a back boiler replacement free through ECO4?
ECO is not a grant scheme; suppliers decide what to fund and you may be asked to contribute. Get a contract before agreeing.