Top 6 Common Boiler Faults and Their Solutions

If your boiler isn’t working properly, it may be down to one of the faults that boilers tend to have. Here are 6 most common boiler faults and their solutions that occur within the UK properties.

1. Faulty automatic air vent

The air vent releases air from the boiler to the outside. Dripping or a build-up of scale at the vent stops it working properly. This should be spotted during a your annual boiler service and addressed as soon as possible so other parts within the boiler should not be damaged long term.

Solution: Replace the vent.

2. Lack of pressure within the system

The central heating combi boilers are designed in a way that they require to have pressure within the central heating pipes. The pressure within the system allows the boiler to easily pump through the hot water through the radiators so the lack of pressure will trigger an error code on your boiler – F1 for Ideal boilers, f22 for Vaillant boilers, A04 for Vokera boilers).

Solution: Top up the water pressure

3. Limescale build-up in central-heating pipes

This is most common in hard-water areas. If the boiler hasn’t been fitted with a magnetic filter, scale deposit build-ups can lead to blockages and cause fluctuations in temperature of hot water taps.

Solution: Fit a scale reducer. Ideally this should happen when a new boiler is installed.

4. Faulty or blocked pressure-relief valve

This may cause constant dripping from the copper pipe leading to the external wall. Often this goes all the way back to a faulty expansion vessel. If the pressure-relief valve is overused, bits of grit can get caught inside it, preventing the valve from sealing properly and making it drip.

Solution: Your engineer should check the expansion vessel and replace the pressure-relief valve.

5. Pump failure

If the pump fails, it would leave you with no heating or hot water. Bad news at any time, particularly in winter. It is caused by sludge in the system, or old age.

A specialist boiler repair company has told us: ‘Energy-efficient combi boilers are manufactured to last 10-12 years. Warranty lengths vary, so you need to check if yours is still covered. If the pump fails in year eight or nine, after the warranty has expired, I will usually advise the customer to replace the whole boiler. Replacing the pump is an expensive job, and you’re not going to get the value of the repair in an old boiler.’

Solution: Replace the pump.

6. Faulty diverter valve

When you switch on your central heating, the boiler lets the water go round the heating system. When you turn the hot water on, it diverts it. If the motor inside the diverter valve fails, instead of diverting the water, the valve can just slide back and forwards in place, or it will stop working because of resistance. So, the system can get ‘stuck’ on hot water or central heating.

Solution: Replace the diverter valve.

7. Sludge in the system

When radiators are hot at the top with cold spots at the bottom, it usually means there is a build-up of sludge. This happens for a number of reasons – lack of proper servicing, poor fitting, lack of cleaning after conversion to a combi system, rust levels, air in the pipes, or the quality of water going through the system.

If you have an older system dating to the 1980s or earlier, powerflushing is unlikely to help. Sludge can bake on to the pipes and become crystallised over time. Also, copper shortages in the late 70s and early 80s led to copper pipes being mixed with steel, which would be washed away by powerflushing.

Solution: The system may need a powerflush, but this is costly and not always the best solution.