Dealing with a boiler leak

Warning: this blog contains advice regarding straightforward mechanical issues so you can see if your boiler is leaking but does not provide advice or guidance regarding gas leaks. If you suspect your boiler may be leaking gas, open all windows and doors, extinguish any naked flames, and contact emergency gas services on 0800 111 999 immediately.

Now the formalities are out of the way…

As we enter the colder seasons of the year, more and more people will be switching their central heating on for the first time since the spring. While most of us wake the dormant beast that resides in the cupboard and then enjoy the warm, comfortable home that follows, some aren’t so lucky. The boiler or central heating system may have been hiding mechanical issues or could have deteriorated over the summer. In this blog we will explain the most common problem boilers may suffer from, and how you can find out if your boiler is leaking.

Know the symptoms of a potential boiler leak

Issues with boilers can go unnoticed for some time and often don’t rear their head until you need the boiler most. Here are some common signs that either your central heating system or boiler is leaking:

The Puddle

Often the first indication that your boiler is leaking is the puddle of water directly under the unit. These can sit and gather for some time if the boiler is hidden away in a cupboard or seldom used room. If you’re using your boiler cupboard to help dry clothes you may find a pile of damp laundry rather than a puddle, but the root cause will be the same. Common points of failure within the boiler are joints and connections in the pipework, or a damaged expansion tank.

You can locate the source of the leak by placing dry coloured paper sheets under the boiler and noting where the drips are landing.

Loss of Pressure

Sometimes there is no discernible leak, evidenced by a pool of water or damp carpet under the boiler - however when you come to switch the boiler on, it may alert you with an error warning light. Upon closer inspection you may notice the water pressure gauge is dangerously low or at zero. This indicates either that your boiler is leaking or that there is a water leak somewhere within your central heating system.

If, however, your central heating system is behaving as it should be, with no obvious signs that something is amiss, you could just have a faulty pressure gauge, which should be replaced.

Rusty Radiators

Take a look at your radiators. They should be clean, without green (copper) or brown (rust) deposits around the valves, joints, connections, or bleed valves. If you can see deterioration to the radiator, or damp or wet spots on the floor under the radiator, you’ve got a leak. These can materialise over time as a result of loose connections, cracked metal or blocked pipework.

You can also listen for hissing around the radiator which will indicate a leak.

What you can do if your central heating system is leaking

The central heating infrastructure fed by the boiler is more accessible and can be worked on by anyone who is competent to do so. So if you note a leaking radiator, by all means have a go at replacing this yourself (see our previous blog on how to do this here). Sometimes the issue is a simple loose plug at the top of the radiator which you can nip tight with an adjustable spanner.

Likewise, if the connecting pipework has a leak, it’s easy to work on this yourself with the proper tools and knowhow. Thermostatic Radiator Valves in particular are easy to replace, and sections of leaking pipework can be cut out and replaced simply too. Just make sure you know how to drain the system down properly before starting work, and that you have all the tools and spare parts at the ready before starting - you don’t want to run to the hardware shop mid-repair!

What you can do if your central heating system is leaking

The central heating infrastructure fed by the boiler is more accessible and can be worked on by anyone who is competent to do so. So if you note a leaking radiator, by all means have a go at replacing this yourself (see our previous blog on how to do this here). Sometimes the issue is a simple loose plug at the top of the radiator which you can nip tight with an adjustable spanner.

Likewise, if the connecting pipework has a leak, it’s easy to work on this yourself with the proper tools and knowhow. Thermostatic Radiator Valves in particular are easy to replace, and sections of leaking pipework can be cut out and replaced simply too. Just make sure you know how to drain the system down properly before starting work, and that you have all the tools and spare parts at the ready before starting - you don’t want to run to the hardware shop mid-repair!

What you can do if your boiler is leaking

If your boiler is leaking, the remedial action is more complicated. The boiler is the beating heart of your central heating system and takes a trained professional to repair and maintain it due to the complicated combination of water, electricity, and gas systems inside.

For this reason, if your boiler is leaking, it’s best to steer clear of attempting a DIY repair, and far better to get a trained professional to identify the source of the leak and rectify it for you. Besides the complicated and expensive nature of the parts inside your boiler, it is also illegal to carry out work (including maintenance) on gas systems in the UK. So not only does it make sense to have a specialist in to repair your boiler, it will also keep you on the right side of the law.

Whatever you determine is the cause of the issue, if your central heating system or boiler is leaking, don’t delay the repairs.  Doing so can lead to further deterioration and ongoing damp can cause woodwork and textiles to rot, and mould and fungi to grow on surfaces which can lead to respiratory problems. Not to mention rusty metalwork falling into disrepair, small leaks turning into big ones… and if your radiator does accumulate a build-up of rust, it can spread this throughout your entire central heating system, eventually ruining your boiler (if you’re concerned about this, check out our power flush service).

So, to paraphrase…if you spot a leak…get it fixed!

You can do it! Apart from when you can’t…

As the warm balmy evenings of the summer start to become fond memories, a functional and safe central heating system and boiler is essential. Don’t forget that a leaking boiler will also affect your hot water supply - so you can say goodbye to hot showers and baths too.

It’s good practice at the start of the autumn period to inspect your radiators and associated pipework to ensure they are in good condition and aren’t exhibiting any signs of damage or deterioration. Most issues that you may encounter can be rectified by a keen DIYer and needn’t cause you too much concern. If your boiler is leaking, however, (and you should now know how to diagnose this) it’s time to get a professional in.