Boiler repair: booking a Gas Safe engineer
What a repair visit involves, which checks you can safely do first, and how to book a Gas Safe registered engineer.
If you smell gas
Leave the boiler alone and call the National Gas Emergency Service on 0800 111 999. Turn off the gas at the meter if it is safe to reach, open doors and windows, and do not touch light switches, sockets or anything with a flame.
Everything else on this page assumes there is no gas smell.
What a repair visit involves
Most boiler repairs start with a diagnostic visit. A Gas Safe registered engineer reads the fault code on the display, checks the pressure, gas supply, flue and controls, and tests the parts most likely to have failed. That usually takes about an hour. For typical prices by part, see our guide to boiler repair cost.
You should then get a fixed price for the repair before any part is ordered. Common parts such as pumps and diverter valves are often on the van, so many repairs are finished on the first visit. Less common parts may need a second trip.
Common faults
| Symptom | Usual cause |
|---|---|
| Pressure keeps dropping | A leak, a faulty pressure relief valve or a flat expansion vessel |
| No heating but hot water works | Diverter valve, pump or thermostat |
| Boiler will not fire up | Frozen condensate pipe, low pressure, ignition or gas valve fault |
| Banging or kettling noise | Limescale or sludge in the heat exchanger |
| Fault code and lockout | Anything from low pressure to a failed sensor or circuit board |
Some of these have safe checks you can do first. Our guides on a boiler losing pressure and a boiler not firing up walk through them.
Repair or replace?
A repair is usually the right call on a boiler under 10 years old with a one-off fault. If the boiler is over 12 years old, has needed several call-outs in the past two years, or the quote is for a major part such as the heat exchanger, compare the cost with a new boiler first. Our guide on whether to repair or replace your boiler sets out the sums, and the boiler replacement section covers the options if a new boiler wins.
Booking a Gas Safe engineer
City Boiler is not a repair company. We connect you with independent local engineers who are Gas Safe registered, and you can check any engineer’s registration in a couple of minutes. When you book, have the boiler make and model, any fault code on the display and a photo of the pressure gauge ready. That helps the engineer bring the likely parts on the first visit. A yearly boiler service catches many of these faults before they leave you without heating.
Typical prices
| Job | Typical price | Typical visit |
|---|---|---|
| Diagnostic visit | £80 to £120 | about 1 hour |
| Pump, valve or fan replacement | £150 to £350 | 1 to 3 hours |
| Main circuit board (PCB) | £250 to £450 | 2 to 3 hours |
| Annual boiler service | £80 to £120 | about 1 hour |
Including VAT, checked October 2026. England prices shown; grants differ in Scotland, Wales and Northern Ireland.
Boiler repair by city
England
- Birmingham
- Bolton
- Bournemouth
- Bradford
- Brighton
- Bristol
- Cambridge
- Chelmsford
- Coventry
- Derby
- Doncaster
- Exeter
- Gloucester
- Huddersfield
- Hull
- Ipswich
- Leeds
- Leicester
- Liverpool
- London
- Luton
- Manchester
- Middlesbrough
- Milton Keynes
- Newcastle
- Northampton
- Norwich
- Nottingham
- Oxford
- Peterborough
- Plymouth
- Portsmouth
- Preston
- Reading
- Sheffield
- Southampton
- Stoke-on-Trent
- Sunderland
- Swindon
- Wakefield
- Warrington
- Wolverhampton
- York
Northern Ireland
Common questions
Can I fix my boiler myself?
You can do a few safe checks: the power, the thermostat, the pressure gauge and a reset as set out in your manual. Anything inside the casing or involving gas must be done by a Gas Safe registered engineer.
What should I do if I smell gas?
Call the National Gas Emergency Service on 0800 111 999 at once. Turn off the gas at the meter if you can do so safely, open windows and do not use switches or naked flames.
Is City Boiler a repair company?
No. City Boiler connects you with independent local engineers who are Gas Safe registered. They quote, carry out and guarantee the repair.
What should I have ready when I book a repair?
The boiler make and model, which is usually on a label under the casing or on the front panel. Note any fault code on the display and the reading on the pressure gauge. A photo of both helps the engineer bring the right parts.