Boiler 17 March 2023

Common gas boiler problems and how to troubleshoot them

Gas boilers are a popular choice for many homeowners, thanks to their efficiency and reliability. However, like all heating systems, gas boilers can experience issues over time. In this article, we’ll discuss some of the most common gas boiler problems and offer tips on how to troubleshoot them.

No hot water

One of the most common gas boiler problems is a lack of hot water. If you’re not getting any hot water, there could be a number of reasons why. The first thing to check is the pilot light. If it’s gone out, you’ll need to relight it. If the pilot light is fine, the issue could be with the thermostat or the heating element. In this case, it’s best to call a qualified gas engineer to diagnose and fix the problem.

Low pressure

Another common gas boiler problem is low pressure. If you’re noticing that the pressure gauge on your boiler is reading low, you may have a leak in your system. Check for any visible leaks around your radiators or pipes, and if you can’t find anything, you may need to bleed your radiators to release any trapped air. If you’re unsure how to do this, consult your boiler’s manual or contact a gas engineer.

Strange noises

If you’re hearing strange noises coming from your gas boiler, this could be a sign of a problem. Rumbling, banging, or whistling noises could indicate a blockage in your system, a faulty pump, or an issue with the heat exchanger. If you’re hearing these types of noises, it’s best to call a gas engineer to investigate and fix the problem.

Boiler keeps switching off

If your gas boiler keeps switching off, this could be due to a number of issues. It could be a problem with the thermostat, a faulty pressure valve, or a blocked flue. Check the thermostat settings to ensure they’re correct, and if that doesn’t work, call a gas engineer to diagnose and fix the problem.

Pilot light won’t stay lit

If your gas boiler’s pilot light won’t stay lit, this could be due to a faulty thermocouple. The thermocouple is a safety device that shuts off the gas supply if the pilot light goes out. If it’s faulty, it can shut off the gas supply even if the pilot light is still lit. In this case, you’ll need to replace the thermocouple or call a gas engineer to do it for you.

Boiler Locked Out With a Fault Code

Modern boilers rarely just stop; they display a code and shut themselves down deliberately. Look it up in the manual before you do anything else, because the code tells you a great deal. A single reset is reasonable. If it locks out again straight afterwards, stop resetting it — the boiler is protecting itself from something, and repeatedly overriding that will not end well.

Have the code to hand when you ring us. It often tells us which part to bring, which can turn two visits into one.

Frozen Condensate Pipe

This is the classic cold-snap call, and it is the one fault on this list you can very often fix yourself. If your boiler stops during a hard frost and makes a gurgling noise, the condensate pipe — the plastic one running outside — has probably frozen.

Pour warm, not boiling, water along the outside section of the pipe, then reset the boiler. Boiling water can crack the pipe, so resist the temptation. If it keeps happening every winter, the pipe is likely too narrow, run too far outside, or poorly lagged, and that is worth putting right properly.

What You Should Never Attempt

The line is clear: anything involving the gas itself, the flue, or the sealed inside of the boiler is Gas Safe work by law. That includes replacing a thermocouple, despite what you may read elsewhere. Bleeding radiators, topping up pressure, resetting a locked-out boiler and thawing a condensate pipe are all fair game. Beyond that, ring somebody.

If you ever smell gas, do not touch any electrical switches. Open the doors and windows, turn the gas off at the meter if you can reach it safely, get out, and call the National Gas Emergency Service on 0800 111 999.

What It Costs to Get It Looked At

Diagnosis and repair are charged at £95 + VAT for the first hour, which is always billable, then £47.50 + VAT an hour after that. Any parts are agreed with you before we fit or order them. A great many of the faults above are resolved within that first hour.

Call 01732 792 454. We are Gas Safe registered under number 951167 and cover Tonbridge, Tunbridge Wells and the surrounding villages — see boiler repairs in Tonbridge.