What To Do If You Have a Leaking Boiler

What To Do If You Have a Leaking Boiler

You have found water where water should not be. Maybe it is a puddle under the boiler. Maybe it is a damp patch on the ceiling below, or the pressure gauge has crept down again and you have topped it up for the third time this month.

First thing. Take a breath. A leaking boiler is annoying and it is expensive to ignore, but it is very rarely about to hurt anybody.

The problem is what most people do next, which is nothing. We hear the same sentence in kitchens all over North Somerset. “It has been doing this for a few weeks now.” And every single time, it would have been cheaper a few weeks ago.

So here is the honest version. No waffle, no scare stories, just what we would tell you if we were stood in your house with a torch.

Quick answer: what to do if you have a leaking boiler

1. Check the pressure gauge. Is it dropping? If yes, the leak is on your heating system and it will stop on its own once the pressure has gone.
2. If the pressure is not dropping, the water is coming from your hot or cold mains, and that will not stop by itself. Turn off your incoming water main at the stopcock.
3. Turn the boiler off at the switch or fused spur, and catch what water you can with a bowl and towels.
4. Do not take the boiler case off. Not ever. That is a Gas Safe job and your insurer will have opinions if you have a go.
5. Ring a Gas Safe registered engineer. Today, not in a fortnight.
6. If you can smell gas, leave the property, do not touch switches, and ring the National Gas Emergency Service on 0800 111 999.

That is the whole thing in six lines. Now the detail that actually matters.

Is a leaking boiler an emergency?

Usually no. Sometimes absolutely yes.

Water on its own is a nuisance. It damages ceilings, floors and plaster, and it costs money, but it is not going to put anyone in hospital. What makes a leaking boiler a genuine emergency is who is in the house and what the weather is doing.

Cold kills people. It really does. If it is winter and there is an elderly person, a very young baby, or somebody unwell in that property with no heating, that is an emergency and it needs sorting the same day. No debate.

The other emergency is when the word “leak” means something other than water.

What is leakingHow urgentWhat to doWater from the boiler or pipeworkSame week. Sooner if it is soaking into the buildingIsolate, catch the water, ring an engineerWater plus no heating, vulnerable person in the houseEmergency, same dayRing us, mention who is in the propertyGas smellImmediate dangerLeave the house, ring 0800 111 999Carbon monoxide alarm going offImmediate dangerVentilate, get everyone out, ring 0800 111 999

Please do not let a boiler run with a CO alarm sounding because “it is probably the battery”. Check it properly.

Where the leak is actually coming from

Here is something most articles will not tell you. It is often not the boiler.

We get called to a “leaking boiler” and find a weeping joint on the pipework feeding it, or a corroded valve on a radiator two rooms away, or a pinhole under a floor. The boiler gets the blame because that is where the pressure gauge lives.

The pressure gauge is your best clue, and it is free to read.

What the gauge is doingWhat it usually meansPressure slowly dropping over days or weeksSmall leak somewhere on the sealed heating system. Could be anywhere, including under floorsPressure drops fast, within minutes of fillingSomething significant is open. Often inside the appliance itselfPressure steady but water still appearingLeak is on the hot or cold mains, not the heating. Turn the stopcock offPressure climbing on its ownDifferent fault, usually the filling loop left open or a failed expansion vessel

While we are here. Do you know where your stopcock is, and does it actually turn?

Go and find out now, before you need it. The amount of homeowners who have no idea where their cold main isolates is honestly mental to me. It is under the kitchen sink in most houses. Turn it, make sure it works, then turn it back. That two minute job has saved people thousands.

A real job: the leak that hid for months

This one is worth telling because it shows how sneaky these things can be.

We were working on a bathroom in an older property. Part of that job meant draining the heating system down and refilling it afterwards, completely routine. Except it would not hold pressure. Get it up to a bar, wait about thirty seconds, and it had gone again.

The customer rang us back, quite reasonably saying, you have worked on my system and now it will not hold. Fair enough. So up into the loft I went, checking every joint we had touched. Nothing. Bone dry. No stains, no drips, nothing on the ceilings.

So I sat down in front of the boiler and filled the system again, and just listened. Quiet house. And I could hear water running.

Pulled the flap down on the case and there it was. Water pouring through the condensate trap. The main heat exchanger had split internally, so system water was escaping inside the appliance and draining straight out through the condensate pipe into the waste. Invisible. No puddle, no damp patch, nothing for anyone to spot.

That leak had been getting slowly worse for a long time. It had hidden itself perfectly. All we did by draining and refilling was change the conditions enough for it to finally show up.

That customer got lucky. They had a Homecare policy, so the heat exchanger was replaced under the cover and it cost them nothing. Great outcome, and credit where it is due.

But we have seen that same fault on plenty of boilers with no cover at all, where the repair simply is not worth doing, and the answer is a new appliance. Same fault, very different day.

The lesson is simple. Losing pressure with no visible leak does not mean there is no leak. It means you have not found it yet.

The mistakes we see again and again

Ignoring it. By a mile the biggest one. People are scared of what it will cost, so they say nothing and hope. Meanwhile the leak is soaking into joists, plaster and floorboards. The repair does not get cheaper while you are worrying about it.

Topping the pressure up forever. Nearly everyone does this. Gauge drops, top it up, carry on. What you are actually doing is feeding fresh water into a sealed system over and over, and fresh water carries oxygen. Oxygen means corrosion, sludge and more leaks. You are not fixing it, you are slowly wrecking the system.

Assuming it is the boiler. Often it is not, and hunting the wrong thing wastes time and money.

Taking the case off. Please do not. We hear “it is my own house, I can do what I like” quite a lot. Maybe so. But when something goes wrong and you make a claim, your insurance company gets to have a look at who worked on that gas appliance, and that is a conversation nobody enjoys.

Waiting for the annual service to mention it. If something changed today, tell us today.

Repair or replace? The honest answer

This is where people expect a sales pitch. You are not getting one.

Whether a leaking boiler is worth repairing comes down to three things, and all three are tied to how old it is.

• How much are the parts?
• How many parts does it need?
• Can you even get the parts?

Age of boilerOur honest viewUnder 5 yearsFix it. There is loads of life left in that appliance and parts are easy5 to 10 yearsUsually worth repairing, depending on what has failed and what it has cost you recently10 to 15 yearsJudgement call. If it is giving you constant grief, replacing is often the cheaper road15 years and upParts get scarce and expensive. Repeated repairs stop making sense

If your boiler is fifteen years old and has had you calling somebody out three times in two winters, you already know the answer. It is painful, and nobody enjoys spending that kind of money. But you can kick the can down the road for way too long and it ends up costing an absolute fortune in dribs and drabs.

Equally, if it is five years old, we are not going to tell you to bin it. That would be daft.

Why this keeps happening: nobody explained it to you

Here is the bit that really winds me up, and it is not the customers fault.

The single biggest thing behind leaks, breakdowns and dead boilers is dirty, neglected systems. No servicing. No inhibitor. No attention paid to the thing that keeps the whole house warm. And the reason for that is not laziness, it is that engineers do not explain. Not what to do, not how, and definately not why.

So people are left with this completely understandable logic. If I ignore it, it is not a problem. And when it becomes a problem, I will pay to fix it then.

Except heating systems do not work like that. Small problems become big ones, quietly, over years.

Look after a decent boiler properly and you can get an extra five, sometimes ten years out of it. Think about what that does to the maths. That three and a half grand you spent is not spread over ten years anymore, it is spread over eighteen or twenty.

We were in a house recently with a boiler that was twenty one years old. Still going. The lady was completely happy to replace it, because she had had so much value out of it. And do you know what, it was a pleasure to work on. Clean system, easy to strip, easy to service. That is not luck. That is what looking after something looks like.

Your leaking boiler checklist

Print this, stick it in the kitchen drawer.

• Photograph the leak and the pressure gauge, with the date, for insurance
• Read the pressure gauge and write the number down
• Watch it for thirty minutes and write it down again
• If pressure is steady but water keeps coming, turn off the stopcock
• Turn the boiler off at its switch or fused spur
• Get towels and a bowl under it, and move anything electrical
• Leave the case alone
• Do not keep repressurising it over and over
• Check whether you have cover, a warranty, or a service plan
• Ring a Gas Safe registered engineer the same day
• If anyone in the house is elderly, very young or unwell, say so when you ring

What we see round here in North Somerset

Our water is hard. That is just a fact of life in Clevedon, Portishead, Nailsea and across the Bristol area, and it means scale. Scale builds up in heat exchangers and hot water systems, makes everything work harder, and shortens the life of the appliance. Proper treatment and a decent service routine deals with it. Doing nothing does not.

A few things people ask about that turn out not to matter much. Salt in the sea air along the coast at Clevedon and Weston super Mare does not really cause boiler problems. Air quality here is decent too, which helps. In parts of a city you can get an installation that meets every regulation perfectly and still struggles, because the air it is drawing in is genuinely polluted and combustion suffers for it. We are lucky on that front.

What we do see is variable plumbing quality, and I am not going to be polite about it. Some of the work we uncover behind panels and under floors is poor. That is not just a local thing though, that is the trade nationally at the moment.

On the older stuff, anyone who has been doing this a while will remember the Chaffoteaux boilers that went into a lot of properties round here. We used to call them the plumbers pension. Thankfully they are mostly gone now.

And one myth worth killing. Boilers have got a lot better in the last five to ten years. Even the cheaper brands are genuinely decent now. There is a lot of snobbery in this trade about badges, and a fair bit of ego, and not always a lot of thinking behind it. The install and the maintenance matter far more than the name on the front.

What we would recommend as professionals

1. Act on day one. A small leak found early is a cheap job. A small leak found in March, that started in January, is a ceiling.
2. Get it serviced properly, every year. Not a quick glance and a sticker. Properly.
3. Look after the system water. Inhibitor, a decent filter, and a flush when it needs one. This is the single biggest thing you can do for the life of your boiler.
4. Learn where your stopcock is. Today.
5. Ask your engineer to explain what they found. If they cannot explain it in plain english, find another engineer.
6. Do not repressurise on repeat. If you are topping it up more than once or twice a year, you have a leak. That is what it is telling you.
   

    summary

   If your boiler is leaking, check the pressure gauge first. If pressure is falling, the leak is on the sealed heating system and it will stop when the pressure runs out. If pressure is steady but water keeps appearing, the leak is on the hot or cold mains, so turn off the incoming water at the stopcock. Turn the boiler off at its switch, catch the water, and never remove the boiler casing because that is Gas Safe work and doing it yourself can invalidate your insurance. Do not repeatedly repressurise the system, as fresh water introduces oxygen and causes corrosion. A water leak is rarely dangerous, but no heating in cold weather with vulnerable occupants is an emergency, and any gas smell or carbon monoxide alarm means leaving the property and calling 0800 111 999. Boilers under five years old are almost always worth repairing. Between ten and fifteen years, repeated faults usually mean replacement is cheaper overall, because spare parts get more expensive and harder to source with age. A boiler losing pressure with no visible water can still be leaking internally and draining out through the condensate pipe. Regular servicing and clean system water can add five to ten years to a boilers working life. Kesselmann Heating & Plumbing covers Clevedon, Portishead, Nailsea, Bristol, Weston super Mare and North Somerset, and normally responds within twenty four hours.