Boiler servicing contracts: Common problems
For those who don’t want a contract, we asked Adrian Fuller, whose company has been highly recommended on our Which? Local service, to say how much common faults cost to repair. These are average prices charged by Adrian’s company in Surrey, in the past year, including parts, labour and VAT. Costs will vary depending on your boiler type and labour costs where you live. Parts are in the order that Adrian's team have needed to replace them this year, with 1 being the most frequently replaced part and 11 the least.
1. Diverter/zone valves
Cost to replace: £235
Directs flow of heated water from the boiler for heating or hot water.
2. Printed Circuit board
Cost to replace: £310
The ‘brain’ – it makes things run together.
3. Pump
Cost to replace: £198
Moves heated water from the boiler, for either heating or hot water.
4. Thermocouple
Cost to replace: £97
Essential component in preventing gas leaks if your pilot light goes out.
5. Fan
Cost to replace: £310
Moves air through the boiler for combustion
6. Ignition
Cost to replace: £120
Ignites the pilot/main flame
7. Expansion vessel
Cost to replace: £324
Prevents sealed heating system from becoming over pressurised.
8. Gas valve
Cost to replace: £340
Regulates gas flow to the burner.
9. Automatic air vent
Cost to replace: £82
Lets air out of the boiler.
10. Overheat thermostat
Cost to replace: £80
Prevents boiler from overheating
11. Pressure relief valve
Cost to replace: £110
Safety component that ensures pressure does not become dangerous.
Other parts
Adrian has not needed to replace a burner or heat exchanger in the last 12 months, but if these parts breakdown, they aren’t cheap to replace. The burner mixes and burns air and gas inside the boiler and the heat exchanger transfers that heat to the water. Adrian quotes a price of approximately £250 to replace a burner and approximately £400 for a heat exchanger.