Hot Water Cylinder Fault in Woking
A homeowner in Woking, GU22 woke up to find they had no hot water. The immersion heater switch had tripped at the consumer unit and kept tripping every time they reset it. They had...
Response time
1 hour
Time on site
2 hours
Cost range
£195
Warranty
12 months
The Problem
A homeowner in Woking, GU22 woke up to find they had no hot water. The immersion heater switch had tripped at the consumer unit and kept tripping every time they reset it. They had been without hot water since the previous evening and needed it restored urgently.
The property had a vented hot water cylinder with two immersion heaters — top and bottom — heated by electricity only, with no gas boiler. The cylinder was approximately 10 years old.
The Diagnosis
We tested both immersion heater elements with a multimeter and found the bottom element had failed — it was showing a very low resistance reading indicating an internal short, which was causing the RCD to trip. The top element tested correctly.
We also checked the cylinder thermostat, which was functioning. The failed element had likely been degrading over time and had finally broken through the element sheathing, causing the electrical fault.
The Repair
We isolated the electrical supply at the consumer unit and drained the hot water cylinder down to below the immersion heater level. The failed bottom immersion heater was unscrewed using a immersion heater spanner and removed. The threaded boss on the cylinder was inspected for any signs of leaking or damage.
A new 27-inch immersion heater element was fitted with a new fibre washer, the cylinder was refilled, and the electrical connections were remade. The supply was restored and the element was tested under load to confirm it was heating correctly.
Isolated electrics and diagnosed shorted immersion element
Drained cylinder and replaced failed element
Refilled, reconnected and tested under load
Outcome & Advice to the Homeowner
Hot water was restored within the same visit. The homeowner was relieved to have the issue resolved the same day. The new immersion heater was covered by a 12-month warranty.
We recommended setting the cylinder thermostat to 60°C to prevent bacterial growth in the cylinder, and advised checking the sacrificial anode on the cylinder if the cylinder was approaching the end of its expected lifespan.
Job Summary
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