No hot water?
What to check first.

First: boiler or immersion?

Most cylinders can be heated two ways: by the boiler, through a coil inside the cylinder, and by an electric immersion heater. Knowing which one has stopped narrows it down quickly.

If the radiators still come on but the hot water doesn't, the problem is usually the timer, the cylinder thermostat or the valve that sends boiler heat to the cylinder. If the heating is off too, start with the boiler. Our guide to a boiler losing pressure covers the most common cause.

While you work it out, switching on the immersion heater (or its boost button) will usually give you hot water from the electric side.

This guide is for homes with a hot water cylinder. With a combi boiler there's no cylinder, so no hot water means the boiler itself needs looking at.

Check the timer and programmer

A power cut, or the clocks changing, can knock a programmer's clock out or reset its settings. Check the time is right and that hot water is set to come on, not left on 'off'.

Try setting hot water to constant or using the one-hour boost. If the cylinder warms up, the problem was the timing, not the system.

Check the cylinder thermostat

Most cylinders have a small dial strapped to the side, usually in the airing cupboard. It's normally set to around 60°C. If it has been knocked down to a low setting, the cylinder will barely heat.

Check the immersion heater

The immersion has its own switch, often a red switch near the airing cupboard, sometimes with a built-in timer. Make sure it's on.

If it still doesn't heat, check your fuse box. A tripped switch that trips again when you reset it usually means the immersion element has failed. Don't keep resetting it, and don't take the cover off the immersion heater: it's mains electricity sitting in water.

Hot water, but not enough

The water across our area is very hard, and limescale builds up on immersion elements and inside cylinders. A scaled element heats slowly and fails sooner.

Other causes are a thermostat set too low, a failing coil, or a cylinder that's simply too small for the household now living there. See the signs your cylinder needs attention.

When to call a plumber

Ring us if the cylinder or its pipework is leaking, if the immersion keeps tripping the electrics, if the checks above haven't brought the hot water back, or if the cylinder bangs and rumbles as it heats.

If it's actively leaking, switch off the immersion heater and turn off the cold supply to the cylinder if you can find the valve, then call 07858 117024.

We replace immersion heaters, thermostats, valves and cylinders. Visit prices are published, and a replacement cylinder gets a fixed quote before any work starts.