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Five checks, in order, before anyone's condemned as broken. Most cold-tap mornings end at step three.
Work through in order: boiler pressure at 1 to 1.5 bar, the hot water control actually calling for heat, the fused switch and consumer unit for a trip, oil level if you're on an oil system, and the immersion heater as backup if you have a cylinder. Nothing there fix it? Ring 020 4577 2888 any hour and report what you found.
Pressure, controls, power, fuel, immersion — in that order. The checklist covers most cold mornings without a call-out.
On a combi, suspect the diverter valve; on a cylinder system, suspect the cylinder thermostat or its valve. Report this exact pattern when you call — it saves diagnosis time.
A combi boiler shares one heat source between the radiators and the hot tap, switching between them with a diverter valve — when that valve sticks on the heating side, radiators stay warm while the taps run cold no matter how long you wait. A system with a separate hot water cylinder works differently: heating and hot water are more independent, so this pattern more often points at a failed cylinder thermostat or a motorised valve not opening on the hot water side.
Either way, the useful thing you can do is exactly what you're doing now: note precisely what works and what doesn't. "Radiators fine, taps stone cold" is a genuinely narrowing clue, and repeating it clearly on the phone means the plumber arrives already halfway to the fault instead of starting from zero.
Usually yes — a partial fault rather than a total one. A low thermostat setting, a failing element, limescale, or a boiler not reaching full output are the regulars.
A thermostat dial nudged down, deliberately or by accident, is worth ruling out first — it's the cheapest possible answer. Beyond that, a cylinder immersion element can fail partially rather than completely, giving warm water instead of none; isolating the immersion on its own, with the boiler left out of the loop, tells you fairly quickly whether the fault sits there or upstream.
Limescale is the other regular around Mid-Ulster's harder water areas — scale build-up inside a cylinder or heat exchanger reduces how efficiently heat transfers, so the system runs but underperforms. None of this is urgent in the way a total loss of hot water is, but a system quietly losing efficiency tends not to fix itself, so report the pattern rather than living with a lukewarm shower indefinitely.
It's an electric element in the cylinder, switched independently of the boiler. Genuinely useful for tonight's bath — not a fix for the underlying fault.
If your home has a hot water cylinder — common in the older housing along Cookstown's main street and in many rural properties — there's usually an immersion heater fitted as standard, wired to its own switch near the airing cupboard or the cylinder itself, clearly marked. Flick it on and you'll typically have a tank of hot water within thirty minutes to an hour, run entirely on electricity and bypassing the boiler fault completely.
A combi boiler heats water on demand with no cylinder to hold a reserve, so there's no immersion heater to fall back on. If you're on a combi with no hot water, the checklist above is what you've got until the plumber arrives.
On a combi boiler that pattern usually points at the diverter valve, which switches flow between heating and hot water and can stick on one side. On a system with a hot water cylinder, it more often points at a failed cylinder thermostat or a valve that isn't opening. Either way, note that heating works and hot water doesn't — that detail alone narrows the fault a long way before the plumber even arrives.
That's often the room thermostat, the programmer or timer not calling for heat, or on some systems a faulty diverter stuck the other way. Check the thermostat is set above room temperature and the timer has a heating slot active right now before assuming a bigger fault. It's a five-second check that regularly turns out to be the whole answer.
Common causes include a thermostat set too low, a partially failed heating element on an immersion, limescale build-up reducing a cylinder's efficiency, or a boiler firing but not reaching full output. Try the immersion on its own first, since it isolates whether the boiler side is the problem, and report what you find when you ring.
It's an electric element inside the hot water cylinder, switched independently of the boiler, usually from a switch near the airing cupboard marked immersion. If your home has a cylinder, flicking it on gives hot water within roughly thirty minutes to an hour while the boiler fault gets sorted — genuinely useful for a bath tonight, not a fix. Combi boilers with no cylinder don't have this option.
In general across the UK, the boiler, cylinder and fixed heating system are the landlord's to repair, and the tenant's job is to report the fault promptly. Check your tenancy agreement and contact your landlord or letting agent before commissioning any work yourself, since arranging it independently can mean struggling to recover the cost.
The main page — how the line works and the patch it covers.
Go to home →Isolate, drain, make safe — the first five minutes in order.
Take the briefing →Pressure drops, lockouts, oil and gas — and the gas hold point.
Take the briefing →What you're cleared to try, and when it's NI Water's sewer.
Take the briefing →Hedged ballparks and the questions to ask before work starts.
Take the briefing →Gentle thawing done right, and the lagging that prevents it.
Take the briefing →Damp patches, falling pressure and the stopcock test.
Take the briefing →Ring any hour, report what you found, and a local plumber covering Cookstown and the townlands takes it from there.
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