Hot water cylinders and water heaters in Sheffield

A vented cylinder is fed from a cold water tank in the loft. It has an open vent pipe and the pressure comes from the height of the tank. Many older Sheffield homes have this setup, and showers in top floor bathrooms can be weak because the tank is only a little higher than the shower.

An unvented cylinder is fed straight from the mains and stores hot water under pressure. It gives stronger showers, but only if the mains supply is good enough. It has safety devices, an expansion vessel and a discharge pipe that must run to a safe place. In England, unvented cylinders fall under Part G of the Building Regulations. The installer must be competent to fit them and the work must be notified to building control or through a competent person scheme.

Water hardness changes how cylinders age. Most of west Sheffield has very soft water. Yorkshire Water's 2025 report puts the Fulwood zone at 9.5 mg/l calcium, so scale on immersion heaters is rare there.

East Sheffield and Rotherham are different. The Aughton and Woodhouse zone, which includes Handsworth, averages 77 mg/l calcium (moderately hard), and the Rotherham and Tinsley zone averages 89.9 mg/l (hard). In those areas immersion elements scale up and fail sooner, and unvented valves can stick. A yearly service is worth more there.

If your mains flow is good, an unvented cylinder can free up the loft and give better showers. If flow is poor, which is common at the top of steep streets, a new vented cylinder or a cylinder with a pump may suit you better.

If you have a small home with one bathroom, a combi boiler with no cylinder might be the simplest answer. We measure the flow at your kitchen tap before recommending anything, because it decides which option will actually work in your house.

Some cylinder faults can wait for a booked visit. Others need action now. If water is coming from the tundish, the small funnel on the discharge pipe of an unvented cylinder, a safety device has opened. Turn off the boiler and immersion heater and get it looked at.

If the cylinder itself is leaking from a seam or the base, turn off the cold feed to it and the heat sources. A copper vented cylinder that has started to weep at the bottom usually needs replacing, not repairing.

If the water is suddenly scalding, the thermostat may have failed. Turn off the immersion heater and set the boiler's hot water control low until it is checked. Lukewarm water and short showers are less urgent but worth sorting, as they often point to a failed immersion element, a sticking motorised valve or a cylinder thermostat in the wrong position.