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Serves: one working shower again. Four checks, in order, before you decide the boiler or cylinder has actually failed.
The short version: check the boiler pressure gauge and top up if it's low, check the thermostat and timer haven't been knocked, check the trip switch at the fuse board, and check the immersion heater switch if you have a cylinder. Four checks, five minutes, and most no-hot-water calls resolve at one of them. Still cold? Ring 020 4577 2888 to be put through to a local plumber, any hour.
Pressure, thermostat and timer, trip switch, immersion — in that order. Most no-hot-water calls trace back to one of these four.
Combi boilers heat water on demand; cylinder systems store it — and each fails in slightly different ways. Know which you have before you ring.
A combi boiler — common in newer builds and recent installs around the town — heats water directly as a tap runs, so a fault usually means every hot tap in the house goes cold together, and there's no immersion backup to fall back on. Older houses and many of the farmhouses through the Route countryside more often run a hot water cylinder, heated either by the boiler or an electric immersion element, which stores a tank of hot water and can run out if demand outstrips what's been heated.
If you're not sure which you have, look for a large insulated tank, usually in an airing cupboard — that's a cylinder system. No tank, just the boiler unit itself with pipes running straight to the taps — that's a combi. Telling the plumber which you have when you call saves time working out what's actually gone wrong.
Lukewarm rather than cold usually points at the thermostat setting or a part-failed element, not a total system failure. An easier fix than no hot water at all, in most cases.
On a cylinder system, check the cylinder thermostat hasn't been turned down — sometimes knocked accidentally, sometimes set low deliberately by a previous occupant to save on the bill, and worth turning back up to around 60°C, both for comfort and to keep the water safely above the temperature where bacteria can grow. On a combi, a lukewarm supply can point at limescale build-up on the heat exchanger, which is more common in hard-water areas and worth mentioning if you've noticed it building up on kettles or shower heads too.
An immersion heater with a part-failed element can also give a lukewarm-not-hot result, since only part of the heating coil is still working — this is a straightforward element swap for a plumber rather than anything to attempt yourself, since it involves working inside the cylinder.
Check the switch itself first — usually a separate switch near the airing cupboard, sometimes on the wall, sometimes a cord pull — and then the trip switch it runs from at the fuse board. If both look fine and it's still not heating, the element inside the cylinder may have failed, which is a job for a plumber rather than a fuse check.
Yes, and it's a useful clue. One cold tap with others running hot points at that tap's own supply or a blockage local to it, not a boiler or cylinder fault, which usually affects every hot tap in the house together. Mention which taps are affected when you call.
On a combi boiler that usually points to a fault inside the boiler itself, such as a failing diverter valve, rather than anything a householder can fix. On a cylinder system it can mean the cylinder is smaller than the household's usage or the thermostat is set too low — either way, worth mentioning the pattern on the call.
Yes, on a combi or any sealed system — pressure that's dropped too low can stop the boiler firing for heating and hot water together. Check the gauge and, if it's low, follow the manual to top it up through the filling loop; if it drops again within days, that's worth a proper look rather than repeated top-ups.
The front of the box — how the line works and the areas it covers.
Go to home →Stopcock, taps, electrics — the first five minutes in order.
Open the card →Pressure drops, error codes, cold radiators — and gas safety.
Open the card →What's safe to try, and when it's NI Water's sewer instead.
Open the card →How the bill is put together and what to ask up front.
Open the card →The gentle thaw — a defrost, not a fry — plus prevention.
Open the card →Damp patches, slipping pressure and the meter test.
Open the card →Any hour, one call, and you're through to a local plumber covering Ballymoney and the townlands around it.
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