How much does a boiler repair cost in the UK?

A standard Gas Safe engineer call-out is typically £70–£120 including the first hour, with parts on top. Common repairs land between £150 and £450 — a diverter valve or pump replacement sits at the higher end, while a thermostat, pressure relief valve or expansion vessel recharge is cheaper.

How long can a landlord leave a tenant without heating?

Total loss of heating or hot water is normally treated as an emergency or high-urgency repair, with attendance expected within 24 hours — especially in cold weather or where a tenant is elderly, disabled or has young children. Temporary heaters should be provided while a repair or replacement is arranged.

Is a landlord legally required to service the boiler?

Landlords must have all gas appliances and flues checked annually by a Gas Safe registered engineer and provide the tenant with a copy of the gas safety record (CP12) within 28 days. A safety check is not the same as a full service, but an annual service is strongly recommended and often required by warranties.

When should a landlord replace rather than repair a boiler?

As a rule of thumb, replace when the boiler is over 12–15 years old, when the repair cost exceeds roughly a third of a new installation, when parts are obsolete, or when it has needed three or more repairs in two years. New installations typically cost £1,800–£3,500 fitted.

Can a tenant be charged for a boiler repair?

Not for normal wear and tear or age-related failure — those are the landlord's responsibility under Section 11. A tenant may be liable where they caused the fault, for example by tampering with controls, blocking a flue or allowing the system to freeze in a property they were responsible for heating.

Blog · Costs

Boiler repair cost UK: landlord guide to prices, timescales and duties

Heating failures are the repair that generates the most complaints, the most council involvement and the most avoidable cost. Here is what UK boiler work really costs a landlord, and how fast you need to move.

Typical UK boiler costs

Job	Typical range	Notes
Gas Safe call-out / diagnostic	£70–£120	Usually includes the first hour
Annual gas safety check (CP12)	£60–£120	Legally required every 12 months
Boiler service	£80–£150	Often bundled with the CP12
Thermostat replacement	£100–£250	Smart controls cost more
Diverter valve	£250–£450	Classic "heating works, no hot water"
Circulating pump	£250–£450	Noisy system, cold radiators
Expansion vessel / PRV	£150–£350	Repeated pressure loss
Power flush	£350–£800	Sludge, cold spots at radiator bottoms
New combi boiler, fitted	£1,800–£3,500	Higher for system changes or relocation

Common faults and what they usually mean

Heating works but no hot water: usually a diverter valve.
Pressure keeps dropping: a leak on the system, a failed expansion vessel, or a weeping pressure relief valve.
Boiler locks out and needs resetting: often ignition, flame sensing or condensate issues.
Frozen condensate pipe: very common in cold snaps and often resolvable over the phone before a call-out is booked.
Cold at the bottom of radiators: system sludge — a power flush or inhibitor dose rather than a boiler fault.
Radiators cold at the top: air — bleeding may be all that is needed.

Two of those — frozen condensate and radiator bleeding — can often be resolved with a photo and a message. That is why triage before dispatch saves real money.

Your legal duties on heating

Section 11 of the Landlord and Tenant Act 1985 requires landlords to keep installations for space heating and water heating in repair and proper working order. Separately, the Gas Safety (Installation and Use) Regulations 1998 require an annual check by a Gas Safe registered engineer, with the record given to the tenant within 28 days and to new tenants at the start of the tenancy.

Excess cold is also a Category 1 hazard under the Housing Health and Safety Rating System, which means a prolonged heating failure in winter can trigger council enforcement, not just a complaint. Our gas safety, EICR and EPC checklist sets out the full certificate cycle.

Repair or replace?

Replace rather than repair when two or more of these are true:

The boiler is more than 12–15 years old.
The quoted repair is more than about a third of a replacement.
Parts are obsolete or on long lead times.
There have been three or more faults in two years.
Efficiency is poor enough to be dragging down the EPC rating.

A newer, efficient boiler also reduces the risk of a winter emergency call-out — the most expensive kind of heating repair there is. See our guide to emergency plumber costs for how out-of-hours premiums stack up.

How Mainto keeps heating jobs moving

A tenant reports "no hot water" with photos of the boiler display. AI triage flags it as high urgency and captures the fault code. Vetted Gas Safe registered tradespeople in the area quote against the job. The landlord approves a price before work starts, funds are held securely, and release requires both the tradesperson and the tenant to confirm the heating is working. Mainto's fee is a flat £5 per completed job.

Frequently asked questions

Get heating fixed before it becomes a complaint

Mainto routes urgent heating jobs to vetted local Gas Safe trades, with quotes up front and payment released only when the tenant confirms it is fixed.