Hot water cylinder installation in London
The cylinder is the part of the hot water system nobody thinks about until there is no hot water. Vented cylinders fed from a loft tank, unvented cylinders running at mains pressure, and the controls and immersion heaters attached to both. We replace them, size them properly and service the ones still working.
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- DBS-checked engineers
- Emergency callout available 24/7
- Price agreed before work starts
Mon–Fri 8:00–17:30 · Emergency callout available 24/7
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What this includes
- Vented and unvented cylinder replacement
- Cylinder sizing based on bathrooms and usage
- Immersion heater and thermostat replacement
- Expansion vessel and pressure relief valve faults
- Annual servicing of unvented systems
- Controls, timers and cylinder stats
Worth knowing first
Some of this may save you a callout entirely. We would rather tell you than not.
Unvented cylinders are notifiable work
An unvented cylinder is a pressurised vessel and installing or servicing one requires a specific qualification on top of general plumbing competence. Ask whoever you are considering to show you theirs — for this work it is a fair question and a reasonable installer will not mind being asked.
Size is about bathrooms, not floor area
What decides the cylinder is how many outlets might run at once and how many people shower in the same hour. A big house with one bathroom needs less than a small house with three.
No hot water is often not the cylinder
On a vented system it is very often the immersion heater or its thermostat, both of which are cheap. Before replacing a cylinder, those should be ruled out — and we will rule them out first.
The airing cupboard is not always the best place now
Modern insulated cylinders lose very little heat, which is why an airing cupboard around one is no longer the drying space it used to be. If space is tight, a cylinder can often go somewhere more useful.
Common questions
Vented or unvented — which should I have?
Unvented gives mains pressure at every tap and needs no loft tank, which suits most modern refits. Vented is simpler, cheaper to maintain and fine where the existing tank and pressure already work.
Should I just switch to a combi instead?
Sometimes. A combi frees up the cupboard and the loft tank, but struggles where two showers run at once. For a one-bathroom flat it is often the better answer; for a family house with three bathrooms it usually is not.
Why is my hot water only lukewarm?
Commonly a failed cylinder thermostat, a failing immersion element, or a heating coil that is scaled up. All three are diagnosable without replacing the cylinder.
How often should a cylinder be serviced?
An unvented cylinder should be checked annually — the expansion vessel and safety valves are the reason. A vented cylinder needs far less, though the immersion and stat are worth checking with the boiler service.
Part of our heating & hot water work
If the job turns out to be a repair rather than an installation, these are the pages that cover it.
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Boiler Installation
A new boiler sized for the property, fitted properly, with the price agreed first.
More on Boiler Installation -
Boiler Service
The annual check that keeps a boiler safe, efficient and inside its warranty terms.
More on Boiler Service
Other appliance work
Need hot water cylinders in London?
Tell us what’s happening and where you are, and we’ll tell you what it costs before anyone starts work.