There is a particular kind of British optimism that says the heating can wait until the first cold snap. Then the snap arrives, you flick the thermostat, and something is wrong. One radiator stays stubbornly cold, another gurgles like a kettle, and the boiler throws a fault code you have never seen. All on the one evening you least wanted a problem.
The fix is exactly what you do with a car: an MOT. Give the heating a proper once-over in the calm of autumn, weeks before you rely on it, so any small fault surfaces while there is still time to sort it. Here are the ten checks worth doing, roughly in the order we would tackle them.
Do this on a mild day, not a freezing one
The whole point of an autumn heating MOT is timing. Run these checks on a comfortable September or October afternoon, when a fault means a leisurely phone call to an engineer rather than a cold house and a fully booked diary. Leave it until December and you are joining the queue with everyone else.
1. Fire It Up Early, on Purpose
The single most useful thing you can do is turn the heating on for twenty minutes before you actually need it. Let every radiator get hot, listen for odd noises, and watch for anything that does not warm up as it should. A summer of standing still is hard on a heating system, and a deliberate test run is how you find the problems on your own terms.
2. Bleed the Radiators
If the top of a radiator is cold while the bottom is warm, air is trapped inside and your system is working harder than it needs to. Bleeding releases that air and lets hot water fill the whole panel again. It takes a couple of minutes per radiator with a bleed key and an old towel, and it is the highest-impact five minutes in this entire list.
Not sure where to start or how far to open the valve? Our step-by-step guide on how to bleed a radiator and when you should walks through it without the guesswork.
3. Hunt for Cold Spots and Balance the System
Once the air is out, notice which radiators heat up quickly and which lag behind. If the ones nearest the boiler are roasting while the far bedrooms barely take the chill off, your system is out of balance. The hot water is taking the path of least resistance and never getting properly around the house.
Balancing evens out the flow so every room warms at a fair rate. It is a bit more involved than bleeding, but it is very doable at home. Our guide on what to do when a radiator is not heating up and how to balance your system covers the method with the lockshield valves.
4. Check the Boiler Pressure
Glance at the pressure gauge on the front of the boiler. For most combi boilers, cold pressure should sit somewhere around 1 to 1.5 bar. If the needle is down in the red or reads zero, the system needs topping up via the filling loop. If it keeps dropping after you top it up, that points to a leak worth investigating rather than ignoring.
5. Test the Thermostat and Radiator Valves
Turn the thermostat up and make sure the boiler responds. If it is an older dial model, autumn is a sensible moment to consider a programmable or smart version that pays you back over the winter. Then walk round and twist each thermostatic radiator valve. Valves that have sat in one position all summer can seize, leaving a radiator stuck fully on or fully off.
| What you notice | Likely cause | First move |
|---|---|---|
| Cold at the top, warm at the bottom | Trapped air | Bleed the radiator |
| Cold at the bottom, warm at the top | Sludge build-up | Consider a power flush |
| Far rooms slow to warm | System out of balance | Balance the radiators |
| Radiator stuck fully on or off | Seized valve pin | Free the TRV pin |
6. Look for Leaks, Drips and Rust
With everything hot, go round on your hands and knees for a minute. Feel under each valve connection and along the pipework for damp patches, and look for tell-tale rust streaks or flaking paint on older radiators. A small weep now becomes a burst joint in January. If you spot anything, our roundup of common radiator problems and how to fix them will help you tell a quick tightening job from a call-the-plumber one.
7. Test the Carbon Monoxide Alarm
This is the one that is not about comfort. Press the test button on your carbon monoxide alarm and replace the batteries if it is due. If you do not have an alarm near your boiler, fit one before you start using the heating heavily. It costs very little and it is the most important item on this whole list.
8. Clear the Air Around Your Radiators
A radiator can only heat a room if the warm air can actually circulate. Long curtains draped over the top, a sofa pushed hard against the front, or a shelf sitting directly above will all trap heat and send your bills up for nothing. Autumn is the moment to nudge the furniture back a few inches and let the radiator do its job.
It is also a fair time to ask whether a tired old panel is really pulling its weight. If a room never quite gets comfortable, a correctly sized modern radiator or a made-to-order column radiator can transform both the warmth and the look of the space.
9. Check the Condensate Pipe
Modern condensing boilers drain a little water through a plastic condensate pipe, and if that pipe runs outside it can freeze solid in a hard frost, shutting the boiler down at the worst possible time. Trace where it exits the house. If it is exposed, lagging it with pipe insulation now is a five-minute job that heads off a very cold morning later.
10. Book a Professional Service If It Is Due
The nine checks above are the homeowner half of the MOT. The other half is the engineer. An annual boiler and heating service keeps your warranty valid, catches the faults you cannot see, and is far easier to book in October than mid-winter. If you cannot remember the last time yours was done, it is due.
Not sure how often is right for your setup? Our guide on how often you should service your heating system lays out the sensible intervals.
Your Two-Minute MOT Summary
- Fire it up early so faults appear on your terms.
- Bleed every radiator that is cold at the top.
- Balance the system if far rooms lag behind.
- Check boiler pressure sits around 1 to 1.5 bar.
- Test the thermostat and TRVs for seizing.
- Look for leaks, drips and rust while everything is hot.
- Test the carbon monoxide alarm and its batteries.
- Clear furniture and curtains away from radiators.
- Lag the condensate pipe if it runs outside.
- Book a service if it is overdue.
Run through those on a mild afternoon and you will walk into winter knowing your heating is ready, rather than hoping it is. If a check turns up a radiator that is past saving, the team at Geyser is happy to help you find the right replacement. Call us on 01204 695387 or email sales@geyser.co.uk.
Frequently Asked Questions
When should I turn my heating on for the first time in autumn?
There is no fixed date, but the useful habit is to run the heating for a short test before you genuinely need it, typically in September or early October. A brief test run on a mild day lets you find trapped air, seized valves or a boiler fault while it is still easy to book an engineer, rather than discovering the problem on the first freezing night.
What is the correct boiler pressure for a combi boiler?
Most combi boilers should sit at roughly 1 to 1.5 bar when the system is cold. If the gauge reads below 1 bar you can usually top it up using the filling loop, and it may climb a little when the heating is running. If pressure keeps falling after topping up, that suggests a leak in the system and is worth having looked at.
Do I need to bleed my radiators every year?
Bleeding once a year, at the start of the heating season, is good practice for most homes. Air naturally works its way into the system over time and collects at the top of radiators, creating cold patches. If you notice cold tops mid-season, bleed them again then. Frequent air build-up can point to a deeper issue worth investigating.
Is an annual heating service really necessary?
Yes, for two reasons. An annual service is usually a condition of keeping your boiler warranty valid, and it catches wear and safety issues, such as flue or combustion problems, that you cannot spot yourself. Booking it in autumn also means you are not waiting for an engineer during the busiest, coldest weeks of the year.
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