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boiler problems

8 Most Common Boiler Problems

Avoid these common boiler problems

Your boiler is the heart of your home, especially during harsh winters when you can’t do without heating or hot water even for a day. Boilers are reliable performers but over time they may start displaying signs of declining efficiency or malfunction. Below are some of the most common boiler problems and their potential causes.

No heat or hot water

Some of the potential causes include airlocks, failure of valves, thermostat problem or low water levels. When you encounter this problem, the first step should be to check the thermostat and the pressure gauge. If they are both working fine, it is likely that you have a broken diaphragm, valve or airlock, and in this case, the broken part will have to be replaced.


Do you hear a strange gurgling/rumbling noise similar to a boiling kettle? This normally happens when sludge or limescale builds up in the heat exchanger and restricts the flow of water. This causes overheating of water and it begins to boil and steam, and you hear the kettle-like sound. The problem is most commonly observed in areas with hard water. When this happens, call an heating expert to flush out the build-up and ensure that the boiler is running at its full efficiency.

Leaking is among the most serious boiler problems

A leaky boiler is usually a result of a problem with a component such as a pump seal or pressure valve. High system pressure can cause a leak from the pressure valve. Similarly, a worn-out pump seal can also cause a leak. If the leak is around the system’s pipes, it is likely because of corrosion. Only a professional can inspect the system, diagnose the problem, and then repair the leak.

Malfunctioning thermostat

Although technically not part of boilers problems lists we are including thermostat issues here because they are so common. If the temperature of your home is lower or higher than you expect despite adjusting the thermostat setting, it could be due to a malfunctioning thermostat. In case there is a problem with the thermostat, it will present itself through short cycling, i.e., the boiler will turn on and off frequently. If you are lucky, just changing the batteries may do the job. If not, you may have to replace your thermostat.

Strange noises

It is normal for the boiler to make some noise when firing up and while in operation. If your boiler is making whistling, gurgling or vibrating noises, it is likely due to air in the system. A failing pump or low water pressure can also cause strange noises. A knocking noise can be a result of expansion and contraction of the heating pipes. A gurgling noise could come from the radiator or a frozen condensate pipe. It is best to call a professional to locate the source of noise and diagnose and correct the problem.

Frozen condensate pipe

The problem is quite common in colder weather, and in homes where the condensate pipe is fitted outdoors or in an unheated place. The boiler’s condensate pipe carries the condensate from the boiler to the outside drain. When the weather becomes too cold, the condensate can freeze and create a blockage. You can safely condensate the pipe safely on your own but if you are not comfortable doing it, call in a professional to do it.

Boiler keeps switching off

This could be due to thermostat malfunction, low water pressure, or lack of water flow due to a closed valve or the pump not circulating water properly. It is best to call an expert to identify the cause and rectify it.

Pilot light going out

The older boilers normally have a pilot light which must stay lit in order to light the larger burner within the boiler. If your boiler’s pilot light keeps switching off it could be due to a deposit build-up in the pilot light, a broken thermocouple or a draught blowing the light off.

These are just some of the boiler problems that homeowners may face. Preventive maintenance is the best way to keep the boiler working at its peak efficiency. Call our team to discuss your boiler problems and schedule a visit.

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