No hot water? Start with what you can see

The page that carries this whole section is no hot water but the heating works, because that is the shape the fault takes most often and because the chain it walks is the same chain every other page here narrows down. Radiators warm, taps cold, and somewhere between the heat source and the tap something has stopped handing the heat across. On a combi that is the diverter valve. On a stored system it is the motorised valve, the cylinder coil or the control that should have called for either. Read that first and the rest of this list becomes a question of which link you have landed on.

If the taps are cold and the radiators are cold with them, the heat source itself has stopped. On a combi the boiler is the water heater, so no hot water from a combi boiler is where that case belongs, and the display usually has something to say about it. On a stored system the boiler can be running perfectly while the hot water never arrives, which is why hot water tank not heating exists as a separate page: the fault is the cylinder or what feeds it, not the appliance. Immersion heater not working covers the backup element, and it is worth knowing about before you assume a locked out boiler means a cold bath, because a cylinder with a working immersion does not care what the boiler is doing.

Lukewarm, or hot then cold, is its own group and it is the one people live with longest. Water not getting hot is the page for it: a thermostat set or failed low, a plate heat exchanger silted up with scale, a cylinder that has lost the layering that keeps the hot at the top. No hot water in the shower is the narrower case where every other tap in the property is fine, which usually moves the fault to the mixer, the cartridge or the pressure feeding that one outlet rather than to the system. How long does hot water take to heat up is there for the reader who has no fault at all and is measuring a normal reheat against an expectation nobody ever set for them.

Water escaping near the cylinder is the urgent group and the only one on this hub that will not wait. Hot water cylinder leaking, overheating or making noise sorts the three symptoms that arrive together more often than they look like they should, because an overheating cylinder and a discharging cylinder are frequently the same fault seen from two ends. Tundish dripping and pressure relief valve leaking are the two discharge faults people most often decide to ignore, and both are the safety system reporting that something upstream of it has already failed. Hot water scalding hot and the cylinder overheating covers the temperature side of that, and hot water cylinder making noise takes each sound in turn, because kettling, banging and a steady hiss are three different problems with three different fixes.

Before any of it, no hot water checklist before you call is five minutes well spent. It is the list of things that cost nothing to put right, and we point people at it ahead of a visit deliberately. Where the answer is genuinely a repair on a sealed system, unvented cylinder repair is where these pages lead, because a cylinder holding mains pressure is the one part of this chain that is not something to work on yourself.