A boiler that won't fire usually shows a fault code or a flashing light. The fix depends entirely on the code — and most can be diagnosed before a callout.
Safe steps you can take in the next 10 minutes — in order.
When to stop and call
Any fault code starting with E, F, or specific numbers your manufacturer says require an engineer. Always when there's a smell of gas — call National Gas first on 0800 111 999.
Most cases of a boiler that won't fire in Thornbury homes come down to one of these.
Quick fix
£110
Typical
£260
Worst case
£700
Pressure or condensate fix: £90–£140. Diverter or expansion vessel: £180–£320. PCB or heat exchanger: £400+.
The service that fixes this
Gas Safe registered boiler installation and replacement — energy-efficient systems from Worcester Bosch, Vaillant, and Ideal with manufacturer warranties.
See boiler installation in Thornbury →Sometimes yes — the steps above cover the common DIY fixes. Any fault code starting with E, F, or specific numbers your manufacturer says require an engineer. Always when there's a smell of gas — call National Gas first on 0800 111 999.
Around £260 for the typical repair (range £110–£700). Pressure or condensate fix: £90–£140. Diverter or expansion vessel: £180–£320. PCB or heat exchanger: £400+.
For genuine emergencies in Thornbury we usually attend within 1–3 hours during weekdays. For non-urgent jobs we typically book within 2–5 working days.
Usually no. A boiler that won't fire can normally wait until the next working day, which keeps the cost down. Genuine emergencies are flooding, no water at all, or gas smells.
We cover Thornbury and the wider South Gloucestershire area for fast plumbing and bathroom repairs.
Call 07927 593 585A small sample of South Gloucestershire work. Every job here was managed by the same team that would handle your Thornbury project.



Same-day call back during working hours. No call centres, no sales pitch — you talk to the person who'd actually do the job in Thornbury.
We don't try to be everything to everyone. Boiler Installation within 25 miles of Yate is our patch, and we know it well enough to spot most quirks before stripping out. That's why our quotes stick.
Boiler Installation jobs in Thornbury are scheduled around the realities below — postcode coverage, nearest roads, councils involved, and the named places we travel to from there.
South Gloucestershire Council — covering BS, GL postcode districts.
We reach Thornbury via M4, M5, M48 — and serve sites within roughly 25 miles of here.
Aztec West · Severnside
South Gloucestershire is reached via the M5 J14, typically 35 minutes from our base.