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Cost your boiler repair.
Common faults and what each costs — what's typically a £150 fix vs what indicates a new boiler.
✓ Updated May 2026✓ Free quotes✓ Vetted pros
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Costs, timelines, pitfalls and the right questions to ask before any central heating starts on boiler Repair.
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Top tips
Hiring a central heating, without the regret.
Four moves that separate a smooth job from a nightmare.
Cheap fix in dying boiler
A £400 part in a 14-year-old boiler is poor value. Often £2,200 for new boiler is better economy.
Sludge causing repeat failures
Pump/valve replacements fail again if system is sludgy. Power flush first.
Out-of-warranty boiler
Repairs not free. Confirm warranty status before agreeing to work.
Generic vs branded parts
Cheap generic parts fail faster. Insist on manufacturer parts.
Costs & timeline
Know what it costs. Know when it ends.
Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
Call-out diagnosticFirst hour
£80–£200
Emergency / out-of-hours call-outEvening/weekend
£180–£400
Pressure-loss / leak fixOften easy fix
£80–£250
Pump replacementIncluding pump cost
£180–£450
Expansion vessel replacementIncluding part
£150–£400
Diverter valve replacementIncluding part
£200–£500
!
Quote spread is typically ± 18% — always get 3 quotes.
At a glance
InfographicThe Central Heating briefing.
Infographic
Central Heating quick-view
Boilers tend to fail in cold weather — when call-out demand is highest. Most repairs are £200–£500, but ageing boilers (12+ years) often justify replacement instead. Expect to pay £80–£800 for typical UK boiler repair.
What Does the Work Involve?
Gas Safe engineer diagnoses the fault. Common: pressure too low (re-pressurise system), pump failure (replace pump), expansion vessel failure (replace), heat exchanger failure (expensive — often justifies replacement), PCB failure (replace circuit board), ignition lockout (clean electrodes, repair flame detection), diverter valve stuck (replace).
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| Call-out diagnostic | 80 | 200 | First hour |
| Emergency / out-of-hours call-out | 180 | 400 | Evening/weekend |
| Pressure-loss / leak fix | 80 | 250 | Often easy fix |
| Pump replacement | 180 | 450 | Including pump cost |
| Expansion vessel replacement | 150 | 400 | Including part |
| Diverter valve replacement | 200 | 500 | Including part |
| PCB (circuit board) replacement | 350 | 800 | Expensive part |
| Heat exchanger replacement | 450 | 1,200 | Often justifies new boiler |
How Long Does It Take?
Diagnostic: 1–2 hours. Pressure/leak fix: 1–2 hours. Pump/valve replacement: 2–4 hours. PCB/heat exchanger: 3–6 hours.
DIY or Professional?
Gas Safe registered only — all gas/boiler work requires registration.
Choosing the Right Tradesperson
Gas Safe registered with your boiler brand experience (Worcester Bosch, Vaillant, Baxi etc). For under-warranty boilers, use manufacturer-accredited engineer to preserve warranty.
UK Regulations
Gas Safety regulations. Any gas work without Gas Safe registration is illegal.
Common Problems
- Cheap fix in dying boiler: A £400 part in a 14-year-old boiler is poor value. Often £2,200 for new boiler is better economy.
- Sludge causing repeat failures: Pump/valve replacements fail again if system is sludgy. Power flush first.
- Out-of-warranty boiler: Repairs not free. Confirm warranty status before agreeing to work.
- Generic vs branded parts: Cheap generic parts fail faster. Insist on manufacturer parts.
Frequently Asked Questions
When is repair pointless vs replacement?
Boiler age × major part cost: a £500 fix on a 12-year-old boiler is 50% of replacement cost — usually better to replace. £200 fix on 7-year-old boiler: repair.
Common boiler fault codes?
E133 (Worcester Bosch): ignition lockout. F22 (Vaillant): low water pressure. F75 (Vaillant): pump issue. F1 (Baxi): low water pressure. App or boiler manual decodes.
How long should a boiler last?
Quality boilers: 12–18 years. Cheap brands: 8–12. Worcester Bosch and Vaillant often reach 20+ years.
Pressure keeps dropping — what's wrong?
Leak in the system (radiator valve, joint, expansion vessel). Find and fix. Filling repeatedly damages the boiler.
Boiler keeps short-cycling — repair?
Usually undersized expansion vessel, or boiler oversized for the heating load. Inspector should diagnose.
Out-of-hours call-out fee fair?
£180–£400 is typical UK emergency. Beware higher quotes — opportunistic pricing exists in cold spells. Have a regular trusted plumber.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
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