Typical boiler repair costs by part
The table shows typical UK prices for common repairs, fitted by a Gas Safe registered engineer, with parts, labour and VAT where charged. The third column lists fault codes on our site that often point to that part. A code is a starting point for the engineer, not a diagnosis on its own, because wiring, sensors and the control board can trigger the same code.
| Part | Typical cost fitted | Common codes that point to it |
|---|---|---|
| Ignition or flame sensing electrode | Typically £100 to £180 | Vaillant F28, Ideal L2, Worcester EA 227, Baxi E133 |
| Flow or return temperature sensor (thermistor) | Typically £90 to £180 | Vaillant F00, Vaillant F01, Ideal F4, Ideal F5 |
| Water pressure sensor | Typically £100 to £220 | Vaillant F75 |
| Overheat thermostat or limit stat | Typically £90 to £180 | Worcester E9 224, Baxi E110, Viessmann F2 |
| Fan | Typically £200 to £400 | Ideal F3, Baxi E160, Worcester C6 215, Vokera A03, Viessmann F9 |
| Main control board (PCB) | Typically £250 to £550 | Ideal F9, Vaillant F63, Baxi E168, Viessmann FD |
| Gas valve | Typically £250 to £450 | Vaillant F61, Vaillant F62 |
| Pump | Typically £250 to £450 | Worcester A1 281, Baxi E125, Ideal L1 |
| Diverter valve | Typically £150 to £350 | Rarely a code; usually heating or hot water missing |
| Expansion vessel recharge or replacement | Typically £80 to £150 recharge, £200 to £400 new | Repeated low pressure, such as Ideal F1 or Baxi E119 |
| Pressure relief valve | Typically £120 to £250 | Repeated low pressure with a dripping pipe outside |
| Condensate pump (floor-standing boilers) | Typically £150 to £300 | Worcester D5 |
| Heat exchanger | Typically £400 to £900 | Leaks from inside the casing, overheating codes |
Individual part guides go into more detail, for example our boiler fan replacement cost, PCB replacement cost and diverter valve replacement cost guides.
Call-out charges and labour rates
Most engineers charge in one of three ways, and it is worth asking which before they arrive.
| Charge | Typical UK cost |
|---|---|
| Call-out or first hour, including diagnosis | Typically £60 to £120 |
| Call-out or first hour in London | Typically £90 to £150 |
| Each extra hour of labour | Typically £50 to £90 |
| Evening, weekend or bank holiday call-out | Often 50 per cent more, sometimes double |
| Fixed-price repair, parts and labour | Typically £150 to £450, depending on the part |
Some engineers carry common parts in the van and finish in one visit. Others need to order a part, which may mean a second visit, and a few charge for it. Parts for popular models from Worcester Bosch, Vaillant, Ideal and Baxi are usually easy to get within a day or two, while parts for older or less common boilers can take longer to arrive.
What pushes a repair to the top or bottom of the range
- The part itself. Genuine parts for Worcester Bosch, Vaillant and Viessmann boilers often cost more than those for budget models. Boards and gas valves are the priciest common parts.
- Where you live. Labour rates in London and the South East are usually higher than in the North, Wales and Scotland.
- Access. A boiler in a loft or a tight kitchen cupboard, or a part buried at the back of the boiler, takes longer to replace.
- When it happens. An emergency call-out on a Sunday in January costs more than a weekday booking in summer.
- Diagnosis time. An intermittent fault can take longer to track down than a part that has clearly failed.
- Warranty. If your boiler is still under manufacturer warranty, the repair may cost nothing, so check your paperwork before booking anyone else.
Checks to do before you pay for a call-out
Several common lockouts have simple causes you can rule out yourself, without opening the boiler:
- Check the pressure gauge. If it is under 1 bar with the system cold, top it up using our guide to repressurising a boiler.
- Check other gas appliances work and that a prepayment meter has credit.
- Check the gas isolation valve under the boiler is open, with the handle in line with the pipe.
- Check the fused spur or plug supplying the boiler, and your fuse box.
- Check the thermostat, timer and programmer settings, including after a power cut or clock change.
- In freezing weather, check for a frozen condensate pipe and thaw it with warm, not boiling, water.
- Press reset as the manual describes, but stop after two or three attempts.
Never remove the boiler casing or try to replace parts yourself. Anything inside the boiler must be done by a Gas Safe registered engineer. If you smell gas, call the National Gas Emergency Service on 0800 111 999.
How to get an accurate repair price
Engineers can give a much closer price over the phone if you have the right details ready. Before you call, note down:
- the make and model of the boiler, printed on the front or on the data badge underneath
- the exact fault code on the display, and whether it clears after a reset or comes straight back
- what the boiler is doing: no heating, no hot water, both, noises, leaks or repeated lockouts
- the pressure reading on the gauge with the system cold
- roughly how old the boiler is and when it was last serviced
Ask whether the price is fixed or hourly, whether diagnosis is included, and what warranty comes with the part and the labour. Many engineers give around 12 months on parts they fit, but terms vary, so get it in writing. If a second visit is needed to fit an ordered part, ask whether there is an extra charge for it. It is also reasonable to ask to see the old part, especially for an expensive item such as a board or gas valve.
Boiler cover or pay as you go?
Boiler cover plans typically cost £10 to £25 a month and usually include an annual service. They can make sense for an older boiler that breaks down often, or if a sudden bill would be hard to pay. Read the exclusions carefully. Many plans exclude sludge damage, existing faults and older boilers, or cap what they pay per claim. For a newer boiler still under warranty, paying for an annual service and repairs as needed is often cheaper.
When a repair stops being worth it
A single repair on a boiler under ten years old is usually worth doing. The picture changes when an older boiler needs a heat exchanger, a PCB or a string of repairs in a short time, or when parts are no longer made. Our guide on whether to repair or replace a boiler covers how to weigh it up, and our new boiler cost guide gives typical replacement prices to compare against.