Hot Water Cylinders, Immersion Heaters & Unvented Systems
No hot water from a stored system is usually a failed immersion element, a stuck motorised valve, a faulty cylinder thermostat, or a timer set incorrectly. An unvented cylinder that discharges water outside needs attention quickly — it indicates an expansion or pressure control fault.
Stored hot water systems are common across older Surrey and South London housing stock, and they fail differently to combi boilers. The parts are cheap; the diagnosis is what takes skill.
Unvented cylinders are pressurised vessels and are subject to specific competency requirements. We will confirm the qualification of the attending engineer when you book.
Hot water cylinder repair, service and replacement
We handle hot water cylinder repair, hot water cylinder servicing and full replacement for both vented (tank-fed) and unvented (mains-pressure) cylinders. Unvented cylinders should be serviced once a year; we can do the unvented cylinder service on the same visit as a repair.
The most common faults are a failed immersion heater element, a sticking motorised valve, a leaking pressure relief valve and limescale build-up — all made worse by the hard water across Surrey, SW London and Sussex.
Call-outs are £99 in standard hours (Mon–Fri 8am–6pm) including the first hour, then £95 per hour.
Can a hot water cylinder be repaired or does it need replacing?
Most faults — immersion elements, thermostats, valves — can be repaired. A cylinder that is leaking from the tank itself, or is badly corroded, usually needs replacing. We tell you which before any work starts.
What's included
- No hot water fault finding on vented and unvented systems
- Immersion heater element and thermostat replacement
- Cylinder thermostats, motorised valves and wiring centres
- Leaking cylinders, connections and tundish discharge
- Cylinder replacement and pipework alterations
Signs of a cylinder problem
- Hot water runs out far faster than it used to
- No hot water but the heating still works
- Water dripping from an outside pipe near the cylinder
- Cylinder is warm at the top only
- Rumbling or knocking from the airing cupboard
How the job runs
- 1
Check
Confirm whether the fault is heat source, controls or the cylinder itself.
- 2
Test
Electrical and temperature testing of elements, stats and valves.
- 3
Quote
Repair versus replacement priced honestly, including cylinder age.
- 4
Install
Component or cylinder replaced and the system re-commissioned.
What it costs
Immersion element replacement is a small fixed job in most cases. Cylinder work and fault finding are charged as a call-out that includes the first hour on site — £99 standard hours (8am–6pm), £129 evenings (6pm–10pm) and Saturdays, £169 nights (10pm–8am), £149 Sundays and £199 bank holidays — with any further time at £95 per hour. Cylinder replacement is quoted per property because pipework, location and access vary enormously.
How our pricing worksBusiness confirmation required: Unvented hot water systems (G3) competency details must be confirmed by the business before being stated on this page.
Hot water cylinders across our coverage area
This service is available in every area we cover. Choose your area for local detail and the things worth knowing about the housing and water supply there.
Hot water cylinders: common questions
Related services
Boiler & Central Heating Plumbing
Heating system plumbing: pressure loss, cold radiators, leaking valves, pumps and controls.
24 Hour Emergency Plumbing
Round-the-clock call-outs for burst pipes, uncontrolled leaks, loss of water and unusable toilets.
Leak Detection & Burst Pipe Repair
Tracing hidden leaks under floors, behind walls and above ceilings, then repairing the pipework properly.
Advice before your hot water cylinders visit
Request your hot water cylinders quote
- Gas Safe registered engineers
- Up to £5 million public liability cover
The 24 Hour Plumber provides hot water cylinders across the GU, KT, SW, CR, RH and BN postcode areas, with calls answered 24/7. Send the details below and we will call you back to talk through the job and the price — nothing is booked until you agree.
Need hot water cylinders? Talk to us now.
Calls answered 24 hours a day, 7 days a week, including bank holidays. Tell us your postcode and what you can see, and we'll give you a realistic arrival window before you commit to anything.
Phone: 020 8798 2063