An annual service is preventative work on a machine that burns gas in your hallway cupboard. Done properly, it catches the £30 part before it becomes the £300 breakdown — and it keeps your manufacturer warranty valid, because every warranty in the business requires an annual service by a Gas Safe registered engineer. Ours is £89 including VAT, takes 45–60 minutes, and covers any make of domestic gas boiler.
The checklist, in plain English
The full sheet runs to 40 points; these are the ones that matter most and the ones you should expect any engineer to be able to show you:
- Visual and casing checks. Case seals, signs of leaks or scorching, the flue run through the property, and clearances around the boiler.
- Flue gas analysis — with a printed reading. An electronic analyser goes in the flue and measures what the boiler is actually burning. This is the single clearest test of combustion health, and it’s recorded before and after any adjustment.
- Gas tightness test. The whole gas run is pressure-tested to confirm nothing is escaping anywhere — not just at the boiler.
- Burner pressure and gas rate. Checked against the manufacturer’s data plate, so the boiler is burning what it was designed to burn.
- Condensate trap cleaned. The trap collects acidic sludge all year; a blocked one causes lockouts — including the frozen-pipe kind we cover in another guide.
- Magnetic filter cleaned. If we fitted it, this is free. The black sludge it catches is what kills pumps and heat exchangers.
- Controls and safety devices tested. Thermostat, timer, pressure relief valve and the boiler’s own cut-outs — the things that keep a fault from becoming a danger.
- Service record emailed the same day. One document your warranty and your landlord certificate both lean on, in your inbox before the van leaves the street.
Two things worth knowing about how the £89 behaves. First, it doesn’t creep: the price on the board is the invoice, and if the engineer finds a fault during the service it gets written up and quoted separately — never “fixed while we were in there” and added to the bill. Second, it doesn’t lapse: we text you a reminder when the next one is due, eleven months on, so the warranty never quietly dies of forgetfulness.
What the cowboys skip
A £45 “service” exists because most of the list above is invisible to the customer. What usually gets skipped: the flue gas analysis (the analyser costs real money and takes real minutes), the tightness test, the condensate trap, and any recorded readings at all. What you get instead is a vacuumed casing and a sticker on the boiler.
The easy filter: ask for the numbers. An engineer who has done the job has flue gas readings, a burner pressure and a tightness test result, and can email you all three without ever popping the van door. If the paperwork is just a tick-list with no figures on it, the instruments never came out.
Service or repair? Don’t pay for the wrong visit
A service is a health check for a boiler that works. If yours is already misbehaving, book a repair instead — a service visit isn’t designed to chase faults, and an honest firm won’t charge you £89 to tell you that.
- Book a repair if: it’s showing a fault code, locking out, losing pressure every few days, kettling (rumbling like a kettle), or the hot water runs lukewarm. Our repair rate is £120 for the whole first hour, diagnosis included.
- Book the £89 service if: it’s working fine and hasn’t been checked in the last 12 months — especially before winter. September to November is the quiet window; January is when everyone rings at once.
- Landlords: the service and the CP12 certificate share most of the same checks, so we do both in one visit for £139 — saving £25 and a second tenant access.
Gas work is never DIY. Anything beyond the boiler’s outside — the case, the burner, the gas run — is legally Gas Safe work. Whoever turns up, ask to see the Gas Safe ID card at the door; ours is reg. 587214, printed on every invoice. And if you ever smell gas, that call goes to the National Gas Emergency line first, free, on 0800 111 999.