A hot water cylinder may not heat water properly because of a control setting, a faulty thermostat or immersion heater, a boiler problem or simply high demand. Limescale and valve faults can also play a part. Because several causes can look the same, it helps to work through them calmly.
How Your Cylinder Is Heated
It helps to know how your system works. Many cylinders are heated by the boiler through a coil inside the cylinder. Hot water from the boiler passes through the coil and warms the stored water. Some cylinders also have an immersion heater, an electric element that can heat the water on its own or as a backup.
Cylinders can be vented, fed from a cold water tank in the loft, or unvented, fed directly from the mains at higher pressure. Any work on an unvented cylinder needs an appropriately competent professional.
Controls, Timers and the Cylinder Thermostat
Start by checking the heating controls. A programmer or timer may be set so the hot water only comes on for a short time, or the clock may be wrong after a power cut. Make sure the hot water is set to come on when you need it.
The cylinder thermostat is usually a small dial strapped to the side of the cylinder. If it is set too low, the water may only get lukewarm. If it is faulty, the boiler may not get the signal to heat the cylinder at all.
A faulty zone valve can also stop hot water from the boiler reaching the cylinder coil. This is something a professional would need to check.
Immersion Heater and Boiler Problems
If your cylinder relies on an immersion heater, a fault with the element or its thermostat can leave the water cold. These are electrical parts, so any fault with them needs a qualified electrician. Do not open the immersion heater cover yourself.
If the boiler is not firing, or the radiators are also playing up, the problem may lie with the boiler. Any work on a gas boiler must be done by a Gas Safe registered engineer.
Demand, Cylinder Size and Limescale
Sometimes the cylinder is working, but it cannot keep up. If more people now live in the home, or several baths and showers run one after another, the cylinder may simply be too small. It may run out of hot water and take a while to recover.
Limescale can also build up over time, coating the coil or immersion heater. This can make heating slower and less efficient.
As there are many possible causes, a professional diagnosis is usually the quickest way to find the real problem. You can read more about our hot water cylinder repairs and the plumbing faults that can be looked at.
If your hot water is not as hot as it should be, call Emergency Plumber Swindon on 01793 569521. We can talk it through and take a look at the plumbing side for you.