Immersion Heater Replacement London
No hot water from your cylinder? Immersion element, thermostat, or full unit replacement across London — same day. London's hard water kills elements fast. We diagnose the fault and quote fixed price before starting.
Diagnose Your Immersion Heater Fault
Six common immersion heater faults — what causes them, what to check yourself, and the expected fix cost.
No Hot Water at All
Likely cause: Failed heating element (most common), tripped MCB at consumer unit, or failed thermostat
Check: Check the RCD/MCB on the immersion circuit hasn't tripped. If tripped, reset once — if it trips again immediately, the element has shorted and needs replacing.
Element replacement £120–£180 · Thermostat replacement £85–£120
Water Lukewarm but Not Hot
Likely cause: Thermostat set too low, failing thermostat, or partial element failure (one of two elements dead)
Check: Check the thermostat dial — should be set to 60°C for Legionella control. If dial is at 60°C and water is still lukewarm, thermostat is failing.
Thermostat replacement £85–£120 · Element check included
Circuit Breaker Keeps Tripping
Likely cause: Element has shorted to earth — typically limescale cracking has exposed the element core
Check: Do not keep resetting the MCB. A persistent trip means active fault. Switch off at consumer unit and call us.
Element replacement £120–£180 (resolves the short)
Water Leaking from Cylinder
Likely cause: Corroded cylinder wall, failed pressure relief valve, or leaking immersion boss
Check: Isolate the cold feed to the cylinder immediately. A leaking cylinder usually requires full cylinder replacement.
Cylinder replacement £650–£1,800 depending on type
Very High Electricity Bills
Likely cause: Limescale-coated element operating at low efficiency, faulty thermostat running element continuously, or no timer control
Check: Check the immersion is on a timer, not running 24/7. If timed correctly and bills are still high, element efficiency has degraded from limescale.
Element replacement £120–£180 · Timer installation £65–£95
Banging / Rumbling from Cylinder
Likely cause: Limescale flaking off the element, trapped air in the cylinder, or expansion noise
Check: Normal to hear some expansion noise. Loud banging or rumbling from the element area indicates significant limescale build-up on the element.
Element replacement with anti-scale element £130–£190
Immersion Heater Element Types
| Element type | Properties | Lifespan in London | Part cost |
|---|---|---|---|
| Standard copper element | Most common. Prone to limescale in hard water areas. 2–4kW. | 3–7 years in London | £15–£40 |
| Titanium / incoloy element | Corrosion-resistant, better limescale resistance. Longer life in hard water. | 5–12 years in London | £30–£80 |
| Dual element (top + bottom) | Two elements — top for quick top-up, bottom for full cylinder heat. Common in larger cylinders. | 3–7 years per element | £25–£60 each |
| Over-sink element | For direct-drive over-sink water heaters (not cylinders). Small, single-element units. | 5–10 years | £15–£35 |
Immersion Heater Prices — London 2026
| Job | Typical time | Price (parts + labour) |
|---|---|---|
| Thermostat replacement | 30–45 min | £85–£120 inc. part |
| Immersion element replacement | 45–90 min | £120–£180 inc. element |
| Full immersion heater (element + stat + cover) | 45–90 min | £145–£200 inc. parts |
| Titanium/incoloy anti-scale element | 45–90 min | £130–£190 inc. element |
| Timer installation (for immersion control) | 30–45 min | £65–£95 inc. timer |
| Vented copper cylinder replacement (+ new element) | 1 day | £650–£950 inc. cylinder |
| Unvented cylinder replacement (G3 qualified) | 1–2 days | £1,200–£1,800 inc. cylinder |
| Immersion boss repack / seal (minor leak) | 30–45 min | £85–£120 |
Fixed quote before we start. No call-out fee. 7 days a week. Unvented cylinder work carried out by G3 qualified engineers.
Immersion Heater Repairs Across London
Same-day response across all 33 London boroughs. Average arrival under 60 minutes.
Immersion Heater FAQs
How much does immersion heater replacement cost in London?
Element replacement costs £120–£180 including the element and labour. Thermostat replacement is £85–£120. A full immersion heater (element + stat) is £145–£200. If the copper cylinder needs replacing, cost is £650–£950 for a vented cylinder or £1,200–£1,800 for an unvented unit. Fixed price given before we start.
Why is my immersion heater not heating the water?
Most common causes: failed heating element (burned out or limescale-coated — very common in London's hard water), failed thermostat, tripped circuit breaker, or failed thermal cut-out. We diagnose with a multimeter on arrival before recommending replacement.
How long does an immersion heater last?
A quality element should last 5–10 years. In London's hard water (280–320 mg/l), limescale coats the element and makes it work harder — London elements typically last 3–7 years. Titanium or incoloy elements last longer. Replacing the element is far cheaper than replacing the cylinder.
Can I replace an immersion heater myself?
Replacing the element is plumbing work, not notifiable electrical work in itself. However, the immersion runs on a dedicated 240V 20A circuit — the electrical connection is Part P notifiable. We connect the replacement element to the existing flex without disturbing the circuit wiring, keeping the job within plumbing scope.
Should I repair or replace the whole cylinder?
If the cylinder is in good condition (no corrosion, no leaks, under 15 years old), replacing the element is almost always the right call — £120–£200 versus £650–£1,800 for a new cylinder. If the cylinder is leaking or badly corroded, full replacement makes more sense. We assess and give an honest recommendation on arrival.
My immersion keeps tripping the circuit breaker — why?
A tripping RCD or MCB on the immersion circuit indicates the element has shorted to earth — typically limescale cracking has exposed the element core. This requires element replacement. Continuing to reset without repair risks the element failing completely. Switch off at the consumer unit and call us.
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