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Hot Water Cylinder Leaks, Repair and Replacement in London
London Cylinder Specialist is the cylinder division of London Leak Specialist. When the water is coming from the cylinder itself, or the cylinder has stopped heating, that division diagnoses it, repairs it or replaces it, across London inside the M25, 24/7.
Quick answer
If the water is coming from the cylinder, one of its valves, the immersion heater, the coil or the discharge pipe, or if you have no hot water, call the cylinder division. If the cylinder is dry and the leak is in a hidden pipe or the tank feed, that stays with our leak detection team. Cylinder diagnosis is a fixed £180 with no call-out fee and no VAT.
One company, two kinds of water problem
London Leak Specialist has always been about water that is somewhere it should not be and cannot easily be seen: behind plaster, under screed, in a buried supply pipe. A hot water cylinder is a different kind of problem. It is a pressure vessel with valves, heating elements and a safety discharge, and it fails in its own ways. So we set it up as a separate division with its own team, called London Cylinder Specialist, and the two work side by side.
The practical benefit is routing. A homeowner with a wet airing cupboard does not know whether the cause is the cylinder or a pipe feeding it, and should not have to. Tell us what you can see and the job goes to whichever side deals with that source.
What the cylinder division handles
- Leaking hot water cylinders, from a weeping joint to a failed cylinder body
- No hot water or lukewarm water, diagnosed to the actual part at fault
- Cylinder repair: immersion heaters, coils, valves, tundish and expansion vessels
- Cylinder replacement, vented or unvented, to your choice of type and size
- New cylinder installation, including pipework, commissioning and Building Regulations
- The annual cylinder service, with a certificate that the cylinder is in a good state for use
How the work is split between the two teams
The dividing line is the cylinder itself. Anything on the cylinder or bolted to it goes to the cylinder division: the cylinder body, its immersion heater, the heating coil, the temperature and pressure relief valve, the tundish and discharge pipe, the expansion vessel and the isolation and control valves around it.
Anything hidden in the pipework stays with leak detection. That means the pipes running to and from the cylinder inside floors and walls, and the tank-feed pipework from the loft or the mains. Finding those leaks takes acoustic listening, thermal imaging, tracer gas and moisture mapping, the methods described on our leak detection in London page, and leak detection is charged at a fixed hourly rate protected by no find, no fee (see pricing).
Sometimes the answer is both. A cylinder can be perfectly sound while a joint behind the cupboard wall is dripping onto the ceiling below, or a cylinder can be failing at the same time as an old pipe nearby. In that case each team takes the part it is built for.
What you see, the likely source and who deals with it
Use this as a first read. It is a guide to where the water most often comes from, not a diagnosis, and it is the same triage we apply when you call.
| What you see | Likely source | Who deals with it |
|---|---|---|
| Water on the airing cupboard floor, tracing back to the cylinder or its joints | Cylinder body, immersion boss, a joint on the cylinder or its valves | Cylinder division |
| Water dripping from the pipe outside the wall, or from the tundish | Relief valve discharging, often an expansion vessel that has lost its charge | Cylinder division |
| No hot water, or hot water that runs out quickly, with the boiler working | Immersion element, thermostat, motorised valve or coil | Cylinder division |
| Damp patch or stain on the ceiling below the cylinder, cupboard dry | Pipe run to or from the cylinder, running inside the floor or wall | Leak detection (LLS) |
| Loft tank overflowing or the cold feed to the cylinder wet along its length | Tank-feed pipework, float valve or buried section of the feed | Leak detection (LLS) |
| Water appearing right after a pipe let go, with the cylinder dry | Burst or split pipe somewhere on the system | Leak detection and repair (LLS) |
When to call which
Call the cylinder division when the cylinder is the obvious suspect: the water trace leads to it, a valve or pipe at the cylinder is dripping, the discharge pipe outside is running, or the hot water has failed while the boiler and heating are fine. Those are cylinder faults far more often than pipe faults, and the diagnosis visit is built for exactly that.
Call leak detection when the cylinder and its fittings are dry but water is showing up somewhere else, when a water meter keeps moving with everything off, or when a ceiling is stained and the source is not clear. A wet ceiling is the classic case, and our page on water leaking through the ceiling explains the first steps. If a pipe has actually split, the burst pipe repair team is the one to ring.
Whichever you choose, the first job is to limit the damage. Isolate the cold supply to the cylinder and switch off the immersion at its own switch if water is near it. Never cap or block a relief valve or discharge pipe on an unvented cylinder, because that valve is the safety device. If you are unsure, describe what you can see and let the right team take it from there.
Cylinder prices, from the cylinder division
These are the cylinder division's prices. No VAT is charged, and there is no call-out fee. Cylinder prices are separate wherever a new cylinder is involved, because the type, size and brand are your choice.
| Job | Price | What it covers |
|---|---|---|
| Cylinder diagnosis | £180 | Fixed, with no call-out fee. The team diagnoses the fault and an easy fix is done straight away. If parts are needed, they are ordered and you get a quotation, priced by the hour or as a fixed price. |
| Annual cylinder service | £180 | Certifies the cylinder is in a good state for use. |
| Cylinder replacement labour | £1,450 | Labour and miscellaneous parts. The cylinder itself is priced separately by type, size and preference. |
| New cylinder installation | £2,400 | Pipework, installation, commissioning and Building Regulations. The cylinder is priced separately. |
These prices belong to the cylinder division and are separate from leak detection, which is charged at the hourly rates on our pricing page. You can read the cylinder side in full at the hot water cylinder specialists, or call them on 020 7870 1666.
Repair or replace: what usually decides it
Most cylinder repairs are to the parts around the cylinder rather than the cylinder itself. An immersion gasket that has hardened, a joint that has loosened with years of heating and cooling, a relief valve that has stuck, an expansion vessel that has lost its air charge: each can be put right without touching the tank. The diagnosis visit exists to find which of these it is, so you are not told to replace a cylinder that only needed a valve.
Water coming through the wall of the cylinder is different. Once the metal has corroded through, there is no sound repair, and a patch on a stored hot water vessel is not something to rely on. Replacement is the honest answer there, and the labour is the fixed £1,450 above, with the new cylinder chosen and priced separately. Our blog guide to a leaking hot water cylinder walks through the common leak points if you want to understand what you are looking at before you call.
Frequently asked questions
My hot water cylinder is leaking. Is that you or the leak detection side?
If the water is coming from the cylinder itself, or from a valve, immersion heater, coil connection or discharge pipe attached to it, it goes to the cylinder division. If the cylinder is dry and the water is appearing elsewhere, such as a ceiling stain below or a wet floor away from the airing cupboard, the source may be a pipe run, and that is a job for leak detection. Describe what you see when you ring and it is routed to the right team.
Can a leaking cylinder be repaired, or does it need replacing?
It depends where the water comes from. A weeping immersion gasket, a loose joint, a failed valve or a tired expansion vessel can be repaired. Water coming through the wall of the cylinder itself means the metal has failed, and the fix is a replacement. The diagnosis visit settles which one you have before any bigger spend is agreed.
How much does a cylinder diagnosis cost?
The cylinder division charges a fixed £180 for diagnosis, with no call-out fee and no VAT. The team comes out and finds the fault, and an easy fix is done on the spot. If parts are needed, they are ordered and you receive a quotation for the repair, priced by the hour or as a fixed price.
What does cylinder replacement cost?
Replacement labour, including miscellaneous parts, is a fixed £1,450. The new cylinder is priced separately because type, size and brand vary widely, so you choose what suits the property. A brand new installation, including pipework, commissioning and Building Regulations, is £2,400, again with the cylinder priced separately. No VAT is charged on either.
What is the annual cylinder service for?
It is a yearly check on the cylinder, its valves and safety components, and it comes with a certificate that the cylinder is in a good state for use. It costs £180. It is most relevant to unvented cylinders, where the safety valves and expansion vessel need to keep working, and to landlords who want a record on file.
Do you cover cylinder work outside the centre of London?
Yes. The cylinder division works across London inside the M25 and is available 24 hours a day, seven days a week.
Not sure whether it is the cylinder?
Tell us what you can see and where. If it is the cylinder, the cylinder division takes it. If it is a hidden pipe, we trace it.