Boilers Behaving Badly? Troubleshooting Common Boiler Problems

When our central heating systems are working, we don’t give them a lot of thought. It’s only when they go wrong that they demand our attention. Usually this happens in the autumn, when boilers are brought back to life after being dormant for the summer months.

Boilers Behaving Badly

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Most boiler failures are due to a few common problems, so here’s how to diagnose what’s wrong and decide whether you can fix the issue yourself or need to call in an expert.

No Heat

If you’re getting no heat or hot water at all from your boiler installation in Woking, you first need to check the system controls. Make sure that the thermostat is at the correct setting and that the programmer is set to turn on the system at the appropriate time. If these things are all right, you may have a problem with low pressure or a frozen condensate pipe – we’ll look at these things shortly – or it could be a problem with a broken diaphragm or valve, in which case you’ll need to consult an expert.

Condensing Boiler Problems

If your boiler installation was done in the last ten years or so, it will be a condensing type and it may well be a combi – without a hot water storage cylinder.

Combi boilers have their own particular problems. They operate on a pressurised system, and the boiler will stop working if the pressure drops. There’s usually a gauge on the boiler to let you monitor the pressure and a filling valve to allow you to top it up if it drops.

Condensing systems have a condensate pipe that drains waste waste away from the boiler. This often runs outside the property, and if it freezes in cold weather the boiler will stop working. You can cure this by pouring warm – but not boiling – water over the pipe.


Strange gurgling and other noises are a common problem with heating systems. Often they’re caused by trapped air, which you can cure by bleeding the radiators. They may also be a symptom of a failing pump.

Noises can also be a result of ‘kettling’ – caused by a build-up of limescale or sludge in the boiler. This causes the water in the system to overheat and boil, resulting in the noises.