How much does a boiler repair cost in the UK?
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A boiler diagnostic call-out from a Gas Safe engineer typically costs £60–£120 including the first hour of labour. In London expect £100–£150+. This is charged whether or not the fault is fixed on the day.
Common repairs and their typical costs: Diverter valve replacement £150–£300 (no hot water on a combi). PCB (printed circuit board) replacement £200–£500 (controls all boiler functions — often the most expensive component). Pump replacement £150–£300. Fan replacement £150–£350. Pressure relief valve £80–£150. Thermistor or sensor £80–£180.
Parts vary significantly by boiler brand. Worcester Bosch and Vaillant parts are well-stocked but can be expensive. Budget brands may have parts on back-order for days or weeks. Ask the engineer to confirm part availability before booking.
The 50% rule: if the repair costs more than 50% of the price of a new boiler, replacement is usually the better investment — especially if the boiler is over 8 years old. A reputable engineer should tell you this honestly rather than pushing an expensive repair.
No-fix, no-fee policies exist but are not universal. Ask before booking. Some engineers charge a reduced call-out fee if the repair is not completed — usually half the standard rate.
Home emergency insurance or boiler cover policies often include repair call-outs at no additional cost. Check your policy before calling a private plumber — you may be paying twice.
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Frequently asked questions
Is it worth repairing a boiler that is 10 years old?
Borderline. If the repair is under £200 and the boiler has been well-maintained, probably yes. If it needs a PCB or heat exchanger, replacement is likely more cost-effective — and you'll benefit from lower running costs.