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A surprising number of no-hot-water calls end at a gauge, a dial or a tripped switch. Run the checks in order — and read the two safety rules first, because they override everything else on this page.
Checks done and the taps still run cold? Ring 020 4577 2888 and report what you found.
Rule one: a gas smell ends the checklist instantly. Leave the property, touch no switches, light nothing, and call the National Gas Emergency Service on 0800 111 999 from outside. Go back in only when you are told it is safe.
Rule two: never open the boiler casing. Every check on this page happens outside it — gauge, filling loop, controls, switches. Work behind the casing of a gas boiler is for an engineer on the Gas Safe Register, and you are entitled to see the ID card before work starts.
Before assuming a fault, rule out the boring explanations. They resolve more of these calls than anyone admits.
On a combi boiler, that split symptom is the classic sign of a failing diverter valve — the part that switches the boiler's output between the radiators and the hot taps. It is a well-known fault with a routine repair, but the valve lives inside the casing, which makes it an engineer's job, not a screwdriver job. Your part is the diagnosis: confirm the thermostat and timer are set sensibly, then report the symptom in exactly those words — heating fine, taps cold. That one sentence tells the person on the other end most of what they need to know.
Plenty of homes around Antrim heat water in a cylinder rather than on demand. The checklist shifts slightly.
Antrim's damp winters sit near zero for long spells, and that is condensate-pipe weather. A boiler that gurgles, then locks out with an error code, very often has ice in the plastic condensate pipe where it runs outside. Pour warm — never boiling — water along the pipe, then reset the boiler once, by the book. If it locks out again, leave it, write down the error code and make the call with the code ready. And if the cold snap has left a tap dribbling as well, read the frozen pipes drill before anything bursts.
On a combi boiler, one circuit working while the other fails usually points at the diverter valve — the component that switches the boiler between radiators and taps. It is a common fault and a known repair, but it lives inside the casing, so it is a job for a registered engineer. Check the controls first, then ring with the symptom described exactly that way.
No. Everything on this page happens outside the casing — the gauge, the filling loop, the controls, the switches. Work behind the casing of a gas boiler is legally restricted to an engineer on the Gas Safe Register, and for good reason. Ask to see the Gas Safe ID card before any gas work starts; a legitimate professional expects the question.
Probably not. If every other hot tap runs warm, the boiler is doing its job and the fault sits between it and that one tap — often an airlock after work on the system, or a failing tap cartridge. A tap that splutters and spits air is the classic airlock sign. Mention which tap and what it does when you ring, and the fix is usually quick.
Three things, in order: the timer or programmer that tells the boiler to heat the cylinder, the cylinder thermostat strapped to its side, and the immersion heater's own switch and fuse — it is usually on a separate circuit at the consumer unit. If the boiler side is dead, the immersion can often stand in as a stopgap for washing water while you arrange the repair.
Often not. A boiler that gurgles and locks out in freezing weather very often has a frozen condensate pipe — the plastic pipe running outside. Thaw it with warm, never boiling, water and reset once by the book. If the boiler locks out again, stop resetting, note the error code and ring with it.
The main page — how the line works and the core drills.
Go to home →Checks in order, pressure top-ups, and the gas rule.
Open the drill →The five steps that stop a burst getting worse.
Open the drill →Prevent the freeze, then thaw gently — never with a flame.
Open the drill →The signs, the stopcock test, and when it turns urgent.
Open the drill →Diagnose first, then clear it step by step.
Open the drill →How pricing works and what to ask before work starts.
Open the drill →Ring any hour with the pressure reading and any error code, and be connected with a local plumber covering Antrim and the surrounding villages.
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