What is a hot water cylinder?

Households with regular and system boilers, are reliant on hot water cylinders to supply a circulation of heated water. A hot water cylinder stores the water, until it’s required at the taps or shower. Quite often, the hot water tank is found in the airing cupboard. However, heating systems that operate alongside a combi boiler don’t require a hot water cylinder because water is heated on demand, meaning there’s no need for the additional storage. 

There are two common types of hot water cylinders found in UK homes. One of these is a direct hot water cylinder, which is heated by an immersion heater. The other, is an indirect hot water cylinder, which relies on an external device to heat the water, like a boiler.  

After deciphering whether your hot water cylinder is direct or indirect, there are two additional cylinders you could have. A vented cylinder works with a cold water tank. The job of the cold tank is to direct water into the cylinder, to be heated by either the boiler or an immersion heater. The cold water tank will be based in the loft, as this system relies more on gravity than pressure.  

On the other hand, an unvented cylinder doesn’t need a cold water tank because water is distributed directly from the mains supply. This results in better water pressure than what is experienced with a gravity-reliant system, leading to an improved shower performance. Without the need for a cold water tank in the loft, unvented cylinders are ideal for properties that have limited space. Although, they can often be more expensive to install because of the extra safety mechanisms they come equipped with.  

While hot water cylinders are often discredited for taking up too much space, they actually come with several benefits. Although, you need a designated space for the cylinder, an unused cupboard can fulfil this role by being converted into an airing cupboard, while also providing storage for your clean towels, clothes and bedding.  

A heating system with a hot water cylinder, can also cope with a high water demand. Therefore, this system is more suitable for the average family of four, than one powered by a combi boiler.  

Additionally, when considering the different ways in which they can heat water, hot water cylinders are quite versatile. Also, they can be partnered with renewable energy sources to provide hot water, usually solar power or biomass fuels.  

A hot water cylinder generally lasts around eight to twelve years, although, it can last longer if it receives regular maintenance checks. While they’re usually reliable, it’s important to observe the performance of your hot water cylinder, when it’s nearing the end of its life expectancy. Signs that your hot water cylinder need replacing includes constant cold water, leaks, strange noises and discoloured hot water.  

If your thinking about replacing your hot water cylinder, then you’ll be keen to know what the financial repercussions are. On its own, a new hot water cylinder will cost around £500, although for an unvented system, you could expect to pay up to £700.