Our boilers work away in our homes largely unnoticed, delivering heating and hot water as and when needed. Understandably, we often only think about them when they suffer a mechanical fault – usually when they start being used in the winter months after a prolonged period of inactivity.

Of the most common problems, some can be addressed by the homeowner, while others may require the attention of a professional heating engineer.

Here are ten of the most common issues:

No hot water or heat

There are many possible reasons why your boiler is not producing hot water or heat, from broken diaphragms and airlocks to motorised valve failures and low water levels. A qualified heating engineer should be called out to identify such issues and replace any faulty parts.

Unusual banging, gurgling or whistling

Such disconcerting noises may not be serious. Trapped air or low water pressure are common causes, as is kettling. In older units it could be a sign of impending pump failure.

Dripping and leaking

Your boiler could be leaking for a number of reasons. Once again, a qualified heating engineer should be called out to diagnose and fix the problem. Broken pump seals or pressure valves are common causes of leaks.

No pilot light

A broken thermocouple may be stopping the gas supply, which could result in the pilot light going out. A draught or a build-up of residue on the pilot light could also cause it to go out.

Frozen condensate pipe

Your boiler's condensate pipe transports acidic water (produced by waste gas) from the boiler to an outside drain. Due to its position this pipe can freeze. Your boiler may display a fault code which will alert you to a condensate pipe issue.

Pressure loss

If your pressure gauge reads below 1, your system could have a pressure issue. Possible reasons for this include a water leak, or a faulty pressure relief valve. If you have recently bled your radiators, pressure could also be down.


If your boiler sounds like a kettle being boiled, it is usually the result of lime scale or sludge build up on the system’s heat exchanger, which can restrict water flow. The water then boils, creating kettle-like sounds.

Thermostat issues

An inaccurate thermostat or one that switches the heating on or off when it's not required to – could be in need of replacement.

Radiators not getting hot

If your radiators are not getting hot or are only hot in patches, they are probably suffering from sludge build-up or trapped air. If the bottom of your radiator getting hot but the top is staying cool, the radiator in question probably needs to be bled. This can be done by you and does not require an engineer.

Boiler turns itself off

Among the common reasons for this are thermostat issues; low water pressure; low water flow due to a closed valve; and poor water circulation caused by a pump issue.

Home Emergency Cover

Boilers can break down at any time, but usually fail in the winter months following a long period of inaction. The sudden pressure on the system’s components often cause a breakdown – at a time of year when a household needs heating and hot water most. The unexpected costs associated with having a boiler repaired in an emergency can put a serious dent in the household budget.

In order to avoid large boiler repair bills – and a number of other potential bills related to home emergencies – many households take out Home Emergency Cover. These insurance policies offer the peace of mind that if something does go wrong with your boiler, the insurer will despatch a vetted, Gas Safe Registered heating engineer to repair the unit, at no cost to the policyholder (notwithstanding any excesses).

Regular home insurance policies rarely include cover for boiler breakdown because boilers fail so often and cost a lot to fix.



startrescue.co.uk always recommend seeking the services of a professional tradesperson If you're not entirely comfortable carrying out repairs or maintenance by yourself.