Most homes have a hot water cylinder to help meet their hot water needs. Hot water cylinders will last a very long time and will only need replacing if they leak, or if you are upgrading to a bigger capacity.

Replacing a hot water cylinder can be a simple task to an experienced professional.
The different types of hot water cylinders

There are two various types of hot water cylinders installed in homes across the UK. They operate to provide hot water to your home with slight differences. Each type has its advantages and disadvantages, and this part of the article describes these. The prices for replacing the hot water cylinder will differ for each type as they are fundamentally different hot water system designs.

Vented hot water cylinders
A vented hot water cylinder system consists of a cold water tank located commonly in the loft which feeds cold water to the cylinder. The cylinder is typically situated in an airing cupboard, with the cold water feed at the bottom of the tank. Heated water rises to the top of the reservoir where it is drawn off for feeding the heating system.

A vent pipe acts as an outlet for air bubbles, and steam should the cylinder overheat and also keeps the cylinder pressure at atmospheric pressure. There are two methods of heating water with vented hot water systems, namely:

Direct heating – immersion heaters are fitted in the cylinder, and they solely provide the hot water.

Indirect heating – a coil within the hot water cylinder is fed via the central heating system and heats the water in the cylinder.

An unvented hot water cylinder connects to the mains cold water rising mains and supplies hot water at mains pressure. Similar heating methods to the vented cylinder also apply to this type of cylinder.
The difference between vented and unvented systems is that there is no water storage tank or vent pipes. Instead, an expansion vessel is connected to the top of the cylinder. The purpose of the expansion vessel is to accommodate expanding water coming from the cylinder. The following safety devices are necessary for unvented cylinders:

Primary and secondary thermostats. The main thermostat maintains the temperature of the water below 65 degrees while the secondary switches off the heater or cuts off water supply if the temperature exceeds 90 degrees Celsius.

At Perrin Heating we can supply and install both vented and unvented types of hot water cylinder