3 common boiler problems – and what to do about them
It can be a pain when your boiler starts playing up; but the good news is, many issues can be resolved by yourself or via a simple repair job.
Here’s three common issues that affect boiler systems – and how you can get them fixed.
Things you should do for any boiler problem
- Check for fault codes. Newer boiler systems will usually display a diagnostic code if something has gone wrong – here’s some of the more common ones.
- Make sure there’s no gas or carbon monoxide leak. The former has a distinct ‘rotten egg’ smell, but the latter is undetectable without a carbon monoxide alarm. Both are extremely dangerous – if you think there might be a gas leak in your home, get out immediately and call 0800 111 999 from a safe distance.
- Don’t do any repairs on a gas boiler yourself! Only Gas Safe registered experts can safely and legally carry out works on a gas-heated boiler system. This article only deals with the things you can legally do yourself to help solve your heating issues.
A leaky boiler demands immediate attention, as it can not only cause harm to your boiler system but can also result in water damage to your home and even neighbouring properties. As soon as you notice a leak, switch off your boiler and your hot and cold water supply to prevent further damage.
Common sources of leaks include:
- Your pressure relief valve (PRV). This part is designed to leak excess water as a safety measure if your boiler pressure is too high. Alternatively, if your leak is accompanied by a neutral or dropping pressure gauge, your PRV may need to be replaced.
- Your temperature valve. This will leak if your boiler gets too hot, which is often a sign of a broken temperature sensor. Avoid using your taps, as the water that comes out may be scaldingly hot!
- Your boiler pump. The rubber seals around your boiler pump can often wear down over time, particularly if your boiler is an older model.
- Corrosion damage. Water can often leak through cracks in badly corroded pipes or tanks. A single dodgy pipe can often be replaced, but more widespread corrosion will require a whole boiler system replacement.
- Poor installation quality. Pipes will often leak from around their fittings if they haven’t been correctly sealed.
Things you can do to fix leaks
Most water leaks will require a professional engineer, but there are a few things you can try to solve certain causes of leaks or speed up the diagnosis process.
- Identify the location of the leak. Once you’ve found where the leak is coming from, test whether the leak only occurs when the boiler is off and cold, when it’s on and warm, or both.
- Check your boiler’s pressure gauge. The needle should sit in the green area between 1 and 2 bar. Any higher or lower suggests a water pressure issue may be behind the leak.
- If your boiler pressure is too high, try bleeding your radiators. This may fix an overfilled boiler, but if a pipe blockage is to blame, you’ll need an engineer to flush out the boiler system.
- Don’t tighten loose joints by yourself! While a small quarter-turn can sometimes stop a leak, it can also over-tighten and damage the washers between pipes – which will quickly turn a small leak into a big problem.
A noisy boiler
Hearing sounds coming from your boiler system can often be annoying, if not downright scary. You might hear a deep rumbling or rattling (usually referred to as ‘kettling’), clunking or banging noises, gurgling, or high-pitched whistling and whining – each of which can be caused by a variety of issues.
Common causes of a noisy boiler include:
- Blockages. Limescale, iron oxide and other nasty sludge can clog up your heating system, restricting the flow of water and causing pressure to build up inside your boiler.
- Leaks. Even tiny leaks can cause a drop in water pressure, and can result in air getting into your heating system. Your radiators will often have cold spots if this is the case.
- A broken pump. A pump which has given up the ghost will shake around and produce banging sounds – this will need to be replaced by a professional engineer.
- Badly fitted pipes. These will make banging or clunking sounds as the varying temperature of the water flow makes them expand or contract.
- A frozen condensate pipe. If you’re dealing with below-freezing weather, your outdoor condensate pipe will often cause an annoying gurgling sound.
Things you can do to fix a noisy boiler
Again, it’s best to get a professional engineer involved if you’re having boiler issues – particularly if you’re dealing with broken or badly fitted parts. However, you do have more options for fixing the problem yourself this time around.
- Check the pressure gauge. If it’s too high, switch off your boiler system immediately and open up the pressure relief valve – the culprit is probably a sludge blockage. If it’s too low, the next thing to do is…
- Top up the water pressure using your filling loop. This may be integrated into the boiler, or you may need to use an external loop. If topping up the pressure doesn’t work…
- If your radiators have cold spots, try bleeding them. This will remove any air built up in the radiator and stop those pesky kettling sounds. Check your pressure gauge after bleeding the radiators – if it’s too low, you’ll need to repressurise using your filling loop. (Be sure to do all this while the system is cold.)
- If your condensate pipe is frozen, try thawing it. The safest option is to place a hot water bottle directly onto the pipe, but make sure you don’t disconnect the pipe by accident.
- Don’t panic! It might sound like your boiler is about to blow up, but the safety features built into your boiler system will prevent a dangerous explosion.
No heating or hot water
Nothing’s more frustrating than going for a morning shower and getting only bitterly cold water dumped on you. If your heating and/or hot water is unpredictable, or doesn’t seem to work at all, it could be down to one of the following problems.
Common causes of heating/hot water interruptions include:
- Power, gas and water supply issues. Your boiler can’t operate without electricity and gas; and power issues can affect your thermostat settings even after the power comes back on. You also won’t be getting any water through your taps at all if the supply to your home has failed.
- A broken diverter valve. This is an issue for combi boilers; it means you’ll either have only hot water with no heating, or only heating with lukewarm or no hot water at all.
- Low pressure. Sludge blockages, trapped air or water leaks will prevent heat and hot water from flowing through your system properly.
Things you can do to fix heating/hot water interruptions
- Check your boiler is receiving water, power and gas. Make sure your stop valve, gas meter and electricity meter are all on, replace any blown fuses, check cold taps and electrical/gas-powered appliances in your home to see if they’re working, and contact your suppliers if necessary.
- Check your thermostat settings. These might have been thrown off by power issues, the clocks going back or forward, or someone else in your family messing with the controls. Make sure both heating and hot water are set to ‘on’, and if your thermostat is set to activate the heating at a temperature lower than 21 degrees, try turning up the setting.
- Check your pressure gauge. As covered earlier in this guide, a boiler system which is losing pressure may require topping up, unblocking or repairing to remove leaks.
- If you’re not getting hot water, try turning on the heating. If your hot water suddenly starts working, you’ll need an engineer to replace your diverter valve (but you’ll at least have hot water in the meantime).