On this page
- What is different about a winter boiler service?
- Why is the condensate route checked before winter?
- Will your boiler's frost protection actually work?
- Why check the pressure after summer?
- Are your heating controls ready?
- What do we look for in the radiators?
- Is your carbon monoxide alarm working?
- Booking your autumn boiler service
- Frequently asked questions
Quick answer
A winter boiler service covers the full set of safety and combustion checks, with extra attention on what fails first in cold weather: the condensate trap and outside pipe run, frost protection, system pressure and the expansion vessel after summer, heating controls, radiator circulation and your carbon monoxide alarm. It takes around 45 to 60 minutes.
Key takeaways
- An autumn service puts extra focus on the parts that fail first in the cold.
- The condensate pipe route outside is checked for freezing risk.
- Pressure and the expansion vessel are checked after months of light use.
- Controls and radiators are tested under a real heating load.
- Test your CO alarm and check its expiry date before the heating season.
Every boiler service includes the same core safety checks, whatever the month. But a boiler serviced at the end of September is about to go from heating a few showers a day to running for hours in freezing weather, so a good engineer looks at it with that in mind. This is what we pay particular attention to on an autumn visit, and why.
What is different about a winter boiler service?
The safety and combustion checks are identical to any other service. The difference is emphasis. In autumn we look harder at anything that freezes, anything that has sat unused over summer, and anything that will be pushed harder once the heating runs daily. The aim is to find the fault in September rather than on the first frosty morning.
For the full list of what any service should include, see our boiler service checklist. The table below summarises the autumn priorities.
| Autumn check | What we look for | Why it matters in winter |
|---|---|---|
| Condensate trap and pipe | Blockages, exposed outside runs, poor fall | A frozen pipe is a common cause of cold-weather lockouts |
| Frost protection | Settings, power, exposed pipework | Protects boilers in garages, lofts and empty homes |
| Pressure and expansion vessel | Cold pressure, vessel charge, relief valve | Pressure faults show up once the system runs hot for hours |
| Controls | Thermostat, programmer, TRVs responding | Faulty controls waste gas or leave rooms cold |
| Radiators | Even heat, cold spots, dirty water | Sludge restricts heat when you need it most |
| CO alarm | Present, working, in date | The heating season is when it matters most |
Why is the condensate route checked before winter?
A condensing boiler produces acidic water that drains through a trap and a plastic pipe, often to an outside drain. If that pipe freezes, the water backs up and the boiler locks out. So on an autumn service we clean the trap and look closely at the outside run: how long it is, whether it is insulated, and whether it has a good fall.
Long, thin, uninsulated runs on north-facing walls are the classic problem. Upgrading to a wider pipe with insulation, or rerouting it internally, is often a small job that saves a January call-out. Our post on condensate pipe checks goes into the detail.
Will your boiler's frost protection actually work?
Most modern boilers have built-in frost protection that fires the boiler or runs the pump if the water inside gets too cold. It only works if the boiler has power and gas, and it protects the boiler itself rather than every pipe in the house. We check it is set up and explain what it does and does not cover.
This matters most for boilers in garages, outbuildings and lofts, and for homes that will be empty over Christmas. If pipework runs through cold spaces, we will point out where lagging or a separate frost thermostat would help.
Why check the pressure after summer?
Over summer the heating circuit barely runs, so small leaks and pressure faults go unnoticed. On an autumn service we check the cold pressure, test the expansion vessel's charge and look at the pressure relief valve and its outside discharge pipe. A vessel that has lost its charge makes the pressure swing high when hot and low when cold.
A healthy system typically sits around 1 to 1.5 bar when cold. If yours keeps needing topping up, that is a fault to fix now rather than something to live with through winter.
Are your heating controls ready?
We run the heating properly during an autumn service, not just the hot water, so we can see the controls working under a real load. That means checking the room thermostat switches the boiler on and off, the programmer is calling for heat when it should, and TRVs are opening and closing rather than stuck after summer.
A few things you can do yourself before winter:
- Replace the batteries in any wireless thermostat or receiver.
- Check your programmer when the clocks go back at the end of October, as older timers do not always adjust themselves.
- Turn each TRV fully up and down a few times to free a pin that has stuck over summer.
What do we look for in the radiators?
With the heating on, radiators should warm evenly across their whole surface. Cold tops mean air; cold bottoms or cold centres usually mean sludge. If a magnetic system filter is fitted, we clean it during the service, and what comes out tells us a lot about the condition of the water in the system.
Where the system water is dirty, we will explain the options, from adding inhibitor to a full system clean, rather than leaving it to cause problems in the coldest weeks.
Is your carbon monoxide alarm working?
We check there is a CO alarm near the boiler and ask you to test it. Alarms have a limited lifespan, and the expiry or replace-by date is usually printed on the back. If yours has passed it, replace it before the heating season. The Gas Safe Register has further advice on the signs of carbon monoxide.
Booking your autumn boiler service
Late September is the last calm window before the October rush. An annual boiler service in Stoke-on-Trent is £90 including VAT, and we cover the wider county too, including boiler servicing in Stafford and Uttoxeter. Call 07896 677083 to book a winter-ready service.
Frequently asked questions
Is an autumn service more expensive than one at other times of year?
No. A standard service is priced the same whatever the month. The autumn focus on condensate, frost protection and controls is part of doing the job properly at that time of year. If an extra job such as rerouting a condensate pipe is recommended, you will be given a separate price first.
Should I leave the heating on while the engineer is working?
Leave the boiler as it is when the engineer arrives. They will switch it off and allow it to cool where needed for cleaning and inspection, then run it on heating and hot water to test it. Having it warmed up beforehand simply helps you both see any problems.
What if my boiler was serviced in spring?
If it was serviced within the last twelve months and has run without problems, it does not need another service just because winter is coming. Instead, run the heating for an hour, bleed any cold radiators, check the pressure, look at the outside condensate pipe and test your CO alarm.
Sources and further reading
Gasmaster Plumbing & Heating has served Stoke-on-Trent since 2005. Every article is written by our Gas Safe registered engineers (reg. 220932) from day to day work on boilers, heating and gas appliances across Staffordshire, Cheshire and Derbyshire.
