Boiler Repair Costs in London: 2026 Price Guide
Boiler repairs in London typically cost £95 to £180 for minor faults, £180 to £350 for mid-range parts such as diverter valves and pumps, and £300 to £500 for major repairs like a PCB replacement. Emergency and out-of-hours visits may add a disclosed premium.
What does boiler repair cost in London in 2026?
| Repair | Typical London price |
|---|---|
| Diagnostic visit | £0 to £75 (usually waived with repair) |
| Minor repair (repressurise, thermostat, sensor) | £95 to £180 |
| Ignition electrodes | £120 to £240 |
| Diverter valve | £180 to £350 |
| Pump replacement | £200 to £350 |
| Fan replacement | £220 to £400 |
| Expansion vessel | £120 to £380 |
| PCB (circuit board) | £300 to £500 |
| Heat exchanger | £400 to £600+ |
These are the ranges our engineers quote across London day to day, and they hold for the common brands: Vaillant, Worcester Bosch, Baxi, Ideal and Glow-worm. The single biggest variable is the part, which is why an honest firm diagnoses first and quotes fixed before touching anything. If someone quotes you a precise price over the phone without knowing the fault, they are guessing, and the guess has a way of growing on the invoice.
What makes a repair cost more or less?
Five things move the number. The brand and model set the part price; a premium boiler's PCB costs more than a budget one's, though mainstream parts (Vaillant, Worcester, Baxi, Ideal) are plentiful and competitive. The boiler's age matters because discontinued parts must be sourced or reconditioned, adding cost and days. Timing matters: a weekday afternoon visit is the base rate, while genuine out-of-hours emergencies can carry a premium, which any decent firm discloses on the phone before dispatching, never afterwards. Access matters more than people expect; a boiler boxed into a fitted kitchen takes longer than one on an open wall. And the fault's history matters most of all: a small leak ignored for a year stops being a £120 fix.
Repair or replace: where the maths flips
The rule London engineers actually use: when a repair costs more than half the price of a new boiler and the boiler is past twelve years old, replacement usually wins on five-year cost. A £450 PCB on a fourteen-year-old unit is the textbook case; a £450 PCB on a six-year-old boiler is just a repair. A new A-rated boiler runs £1,800 to £2,800 installed for a typical combi swap, trims gas bills by 10 to 20 per cent, and carries up to a ten-year warranty. Our repair-or-replace guidance and installation prices are covered in full on the boiler installation page, and any engineer we send will price both paths honestly when the boiler sits near the line.
Want a real number instead of a range? Describe the fault, get a fixed quote after diagnosis, and pay only what was quoted. No call-out fee across London.
How to avoid overpaying for a boiler repair
Four habits protect you. Insist on a fixed quote after diagnosis, in writing, before work starts; hourly open-ended billing is where bills breed. Check the engineer's Gas Safe ID at the door and verify the number free at gassaferegister.co.uk; it takes thirty seconds and screens out the cowboys entirely. Ask what happens to the diagnostic fee if you proceed; reputable firms fold it into the repair. And be suspicious of both extremes: the too-cheap phone quote that doubles on site, and the instant condemnation of a boiler that "cannot be repaired" by someone who happens to sell boilers. A second opinion on a condemnation costs little and regularly saves four figures.
London repair costs, quick answers
Many firms charge one; we do not, and the diagnostic is free when the repair goes ahead. Always ask before booking anyone.
The repair itself costs the same as the table above; out-of-hours response may add a disclosed premium. Get the total confirmed on the phone.
Slightly, but the gap is smaller than reputation suggests; parts cost the same everywhere, and labour is the difference.
Some home emergency policies do; check the excess against the table above, because on minor repairs the excess sometimes exceeds the bill.
Gas Safe registered engineer, [X] years in London heating. Registration checkable at gassaferegister.co.uk.