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A cold tap on a cold morning is a miserable surprise. Most of the time the cause is something small — here's how to find it before you reach for the phone.
No hot water at all — what do we check first? Boiler pressure, then the thermostat and timer, then any tripped switch at the consumer unit, then — if you have a cylinder — the immersion heater. Run through those in order and you'll fix a fair share of "dead" systems without anyone leaving the house. Still cold? Ring 020 4577 2888 to be put through to a local plumber.
Four checks, in order: power, pressure, controls, then the specific culprit for your system. Most households find the answer somewhere in the first three.
None of this takes more than a few minutes, and whatever you find — or don't — makes for a much sharper phone call afterwards.
Look for a tank. No hot water cylinder anywhere in the house — loft, airing cupboard, utility room — means you're on a combi, and the whole fault sits inside the boiler casing. A cylinder means more parts, and more places to check.
A combi boiler heats water on demand, so a hot-water fault on a combi is nearly always the boiler itself — its diverter valve, its plate heat exchanger, or a sensor telling it something's wrong. There's a genuine limit to what you can check yourself beyond pressure and the display code before it's a job for a plumber.
A cylinder system stores hot water in a tank, heated either by an immersion element or by the boiler through a coil, and controlled by its own thermostat and a motorised valve. More parts means more places for a fault to hide, but also more you can rule out yourself — the cylinder thermostat dial, the immersion switch, whether the tank itself feels warm to the touch partway up. Older houses around Limavady, especially ones extended or renovated in stages, are more likely to still be running a cylinder than a newer estate build.
If you have a cylinder, yes — it's a five-minute check and a genuinely common answer. Look for the switch, usually a red indicator light near the airing cupboard.
The immersion heater is an electric element sitting inside the hot water cylinder, and on plenty of homes it's the quiet backup for when the boiler's off or struggling — some households use it as their main hot water source entirely, particularly where oil deliveries are being stretched out. Check its switch is on, check the trip hasn't gone at the consumer unit, and give it half an hour or so to heat a tank of water before deciding it's failed; it's slower than a boiler, not broken just because it's not instant.
If the switch is on, the trip is fine, and there's still no warmth building in the tank after a reasonable wait, the element itself may have failed — a wearing part after years of service, nothing alarming, but not a DIY replacement given it sits in a pressurised, wired system. That's a fair job to hand to a plumber.
On a combi boiler it usually points to the diverter valve, the part that switches the boiler's output between the taps and the radiators — if it's stuck on heating, the taps run cold no matter what the thermostat says. On a system with a hot water cylinder, check the cylinder thermostat and the motorised valve first, since either can leave the tank cold while the radiators run fine.
Not usually the same fault, though it can share a cause. Check the room thermostat and timer settings first — a programme knocked out by a power cut is a common, boring answer. If those look right, it's often the same diverter or motorised valve as the reverse problem, or air trapped in the radiators keeping the heat from circulating.
If you have a hot water cylinder, quite possibly. Check the immersion switch, usually a red light near the airing cupboard or on the cylinder itself, and check the trip hasn't gone at the consumer unit. A tripped immersion, or an element that's finally failed after years of quiet service, is a fair diagnosis if the boiler itself is otherwise firing normally.
Genuinely, that's your call, not ours. No hot water is uncomfortable and inconvenient, but on its own it rarely causes damage the way a burst pipe or an active leak does, so plenty of households choose to wait for daytime rates rather than pay an out-of-hours premium. If there's a wider fault alongside it, or vulnerable people in the house who need warmth or washing facilities urgently, that changes the calculation — say so when you ring.
The main page — how the line works and the areas it covers.
Go to home →The first five minutes, in the right order.
Read the letter →Pressure drops, no heat, error codes — and gas safety.
Read the letter →What to try yourself and when it's the sewer, not your drain.
Read the letter →Honest ballparks and the questions to ask before work starts.
Read the letter →Thawing safely with gentle heat — and the lagging that prevents it.
Read the letter →Damp patches, dropping pressure and the stopcock test.
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