Why has my immersion heater stopped working?

The most common cause is a failed heating element. Hard water areas like London accelerate limescale build-up on the element, which causes it to overheat and burn out. The thermostat can also fail independently. A plumber can test both components and replace whichever has failed.

What is the difference between a vented and unvented hot water system?

A vented system has a cold water tank in the loft that feeds the hot water cylinder by gravity. An unvented system is connected directly to the mains water supply, giving higher water pressure at the taps. Unvented systems require annual servicing by a qualified engineer and have additional safety devices that need regular testing.

Should I repair my hot water cylinder or replace it?

If the cylinder itself is leaking from the body rather than a fitting, replacement is usually the better option. A cylinder with internal corrosion will develop further leaks over time. If the fault is limited to the immersion element, thermostat, or a fitting, a repair is typically more cost-effective. Your plumber will advise based on the condition and age of the cylinder.

Water Heater Repair in London

No hot water is more than an inconvenience — it disrupts your morning routine, your washing, and your household. Whether your immersion heater has failed, your hot water cylinder is leaking, or your unvented system has lost pressure, OnCall Home Repairs connects you with qualified plumbers and heating engineers in London who can diagnose and repair the fault promptly.

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Types of Water Heater Problems We Handle

Hot water systems vary considerably across London properties. Newer homes typically have a combination boiler that heats water on demand, but many older properties still use a separate hot water cylinder heated by an immersion heater, a back boiler, or the central heating system. Each type has its own set of common faults.

Immersion heater failures are among the most common call-outs. The heating element corrodes over time, especially in hard water areas like Greater London, and eventually stops working. The thermostat can also fail, resulting in either no hot water or dangerously overheated water. Cylinder leaks usually develop at fittings or from internal corrosion, and unvented systems can lose pressure or trip safety devices if expansion vessels fail.

Our plumbers handle all types of water heating systems. If the fault is related to your boiler, we can arrange that repair as well. For properties where the hot water cylinder has reached end of life, we can advise on replacement options including modern unvented cylinders or switching to a combination boiler that eliminates the need for a cylinder altogether.

How Water Heater Repair Works

Describe the Symptoms

Tell us what is happening: no hot water at all, lukewarm water that does not get fully hot, a leaking cylinder, or water that overheats. Let us know the type of system you have if you can. This helps us send a plumber with the right parts and experience.

Fault Diagnosis

The plumber tests the heating element, thermostat, and any safety devices. For unvented systems, they check the expansion vessel pressure, temperature and pressure relief valve, and tundish discharge. The root cause is identified and explained to you in plain terms.

Repair and Testing

Faulty immersion elements are replaced, thermostats are recalibrated or swapped, leaking fittings are resealed, and safety valves are tested. The plumber confirms that the system is heating water to the correct temperature and holding pressure before leaving.

Related Services

Boiler Repair Boiler Installation Bathroom Plumbing

Water Heater Repair Across London

Our plumbers and heating engineers attend water heater repairs across London, Westminster, Camden, Islington, Lambeth, Southwark, and surrounding areas. If you have no hot water and need a same-day repair, let us know when you call and we will prioritise your booking.

LondonWestminsterCamdenIslingtonHackneySouthwarkLambethGreenwichWandsworthHammersmithKensingtonEalingBrentHaringeyNewhamCroydonBromleyTower HamletsLewisham

Frequently Asked Questions

No Hot Water? Get It Fixed.

A cold shower is nobody’s idea of a good morning. Call OnCall Home Repairs and we will connect you with a qualified plumber in London who can restore your hot water supply.

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