Twelve Common Causes Of Boiler Repair

When a boiler needs repair it gives different signals, of which you need to be aware to prevent accidents or costlier repairs down the road.

Here is a list of the most common problems that a boiler presents when it needs a repair job.

1. There is no heat or hot water.

In the case of lack of heat or hot water, there can be several causes for the malfunction of the boiler, like low water levels, a breakdown on the heating element, failure in valves or airlocks.

2. The pilot light goes out frequently.

If it is a gas boiler, check for air drafts, or deposit build-up. If it is electric, check the power supply and the circuit breaker switch.

3. The condensate pipe freezes

The condensate pipe expels acidic water. Usually, this pipe drains outside and is exposed to the weather. In case of extremely low temperatures, the water in the pipe freezes, causing a blockage, which originates a condensate back up, shutting the boiler down.

4. Sounds

Kettling is a sound similar to the one produced by a kettle boiling on your stovetop. In regions of hard water, calcium carbonate leaves a residue that builds upon the boiler’s heat exchange, and salt that settles on the bottom of the boiler. When the water gets too hot, salt steams, expanding the boiler and causing the kittling sound. If there is a sound like that coming from your boiler, call a technician right away.


Banging is usually caused by air in the system or a broken pump.

Popping or cracking

It is probably caused by mineral deposits, which prevent the boiler from heating the water properly.


Faulty bearings generally produce grinding noises in the water pump.

5. Loss of pressure of hot water

Check the user manual for an explanation about how to restore pressure in the boiler. A cause of loss of pressure might be a water leak in the water lines or recent bleeding of the radiators. Other reasons may be build up into the water pipes that restrict the water flow, or an open valve.

6. The boiler switches off.

The causes may be low water pressure, thermostat problems, the air in the system, or a broken pump.

7. Problems with thermostat

A malfunctioning thermostat can cause many of the other issues in the boiler. Check the thermostat, and if it is malfunctioning, change it.

8. Overheating boiler

Check the temperature settings; there might be a failure in the control systems. Additionally, check the thermostat.

9. Leaking boiler

  • A leaking boiler waists fuel and works in excess because it has to make up for the lost water by heating more quantities of cold water.
  • Check if it is on the pressure relief valve due to excess pressure.
  • The temperature of the boiler is too high if the leak is on the temperature valve.
  • Corrosion may be the cause of the leak is located on the pipes or tanks.
  • Lack of heat in the radiator
  • When the bottom of the radiator is hot, and the top is warm, there is air in the system. Bleed the radiator.

10. Oil-gas odors

In case of an unusual smell, like oil or gas, open the windows, turn off the control valve, leave your house and call an emergency service immediately. Do not try to fix this problem by yourself. Install a carbon monoxide detector. It is the best preventive measure if your boiler works with natural gas.

11. Sediment

When the water comes out muddy, it is a signal that the boiler has an accumulation of deposits. The best course of action is to call a technician.

12. Rust

If the boiler shows rust, it is probably best to change it.


A well kept modern boiler should give you years of good service. On the other hand, boilers that are several years of use need maintenance and repair. Hence, it would be better if you are aware of the signals that they give when they are malfunctioning, to avoid major damages or probable injuries. If you need to maintain or repair your boiler contact us here.

Sources: The Spruce