Boiler

Why is the boiler leaking water?

“Leaking water” on a boiler does not identify one failed part by itself. Common paths include a hose, seal or connection leak, an overfill or level-control issue, a drain/condensate path problem; the exact model, any error code and measured values determine diagnosis.

Guide summary

“Leaking water” on a boiler does not identify one failed part by itself. Common paths include a hose, seal or connection leak, an overfill or level-control issue, a drain/condensate path problem; the exact model, any error code and measured values determine diagnosis.

Quick answer

“Leaking water” on a boiler does not identify one failed part by itself. Common paths include a hose, seal or connection leak, an overfill or level-control issue, a drain/condensate path problem; the exact model, any error code and measured values determine diagnosis.

Likely causes

a hose, seal or connection leak; an overfill or level-control issue; a drain/condensate path problem; an internal pump, tray or water-circuit leak.

Safe checks

Check only user-accessible items such as the socket, valves, door and external hoses; Note any displayed code and the stage of the cycle when the problem begins; Photograph the model/product label and do not dismantle the appliance.

What a technician checks

stored error history and live sensor values where supported; power supply, wiring/connectors and related actuator measurements; functional testing of the relevant mechanical/hydraulic/air circuit.

When to stop using the appliance

Stop using the appliance if water reaches electrical parts, there is a burning smell/smoke, the breaker repeatedly trips, gas is smelled, or the unit overheats abnormally. Isolate power safely and seek professional help.

Technical safety note

If gas is smelled, do not use the boiler. Close the gas valve if safe, ventilate, avoid electrical switches or open flames and contact the relevant gas emergency service. Also stop use for major water leakage, smoke or repeated electrical faults.

Related fault symptoms

Technical references

References link to manufacturer technical information. Onarhane is an independent service and these links do not imply authorised-service status.

Last updated: 2026-09-05

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Onarhane is an independent technical service provider. Brand names belong to their respective owners. Unless explicitly stated, Onarhane is not an authorised service centre, dealer or official representative of those brands. For products under manufacturer warranty, use the manufacturer’s authorised service channel.