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Unvented hot water cylinders have soared in popularity and can now be found in most homes across the UK. Connected directly to your mains water system, unvented cylinders ensure copious amounts of stored hot water is available on demand and they operate at mains pressure to offer much higher flow rates. This allows you to enjoy improved shower and bath performance all year round!

How do they work?

In an unvented system there is no cold water tank – instead a sealed hot water cylinder is fed directly by the cold water mains. An unvented cylinder is kept under pressure from incoming water supply and is heated by either immersion heaters (a direct model) or by a heat source located outside the vessel such as a boiler or wet solar system (an indirect model).

An unvented cylinder will have outlet pipe work connected to it that distributes the heated content of the cylinder (hot water) to multiple outlets around the house. As soon as an outlet (i.e tap, shower) is used, the pressure of the incoming cold water displaces the hot water content in the cylinder towards the open outlet at mains pressure.

Unvented systems are ‘sealed’, so they require an expansion vessel either next to or incorporated within the boiler or cylinder. An expansion vessel allows for the expansion of water in the system as it heats up, and accommodates the increase in pressure by up to 4.5 bar.

Unvented cylinders are designed to withstand considerable internal forces and are extremely safe to use when fitted with all the correct pressure equipment. They are usually made from stainless steel due to the high tensile strength that can be achieved from a fairly thin sheet.

Unvented cylinder final diagram 1

What are the benefits?

Unvented cylinders free up valuable space in your property and tend to provide stronger water pressure than an open vented system. This is because unvented cylinders are directly supplied by the mains, but of course this depends on the strength of the mains in the first place.

Unvented hot water cylinders are also perfect space-saving options for the modern home. An unvented hot water cylinder doesn’t require a feeder tank in the loft and frees up valuable space in your property. Unlike vented cylinders, the unvented cylinder doesn’t rely on gravity to function, so it can be installed almost anywhere in your home! This makes it easier to store in a place more suitable for you.

Other advantages of installing an unvented system include reduced noise in the system. This is due to the fact that there is no cold water filling up the water storage cistern. The unvented system is completely sealed too, so the water is not at risk of contamination and you don’t have to worry about the water tank freezing throughout winter.

Do I need a new cylinder?

An unvented hot water cylinder generally lasts for 30 plus years when fitted to the highest standard. If your cylinder is beginning to leak water, then it is time to replace it. At any point, the leaking water can get worse and cause substantial damage to your property. Always check for any damp patches surrounding the cylinder and consult your plumber to check for any signs of water damage.

Types available

Hot water cylinder capacity varies between 90 and 400 litres for domestic supply. To make sure you pick the perfect cylinder for your home, PlumbNation has a wide range of unvented cylinders that are suitable for almost any property. These include:

Standard unvented cylinders

Pre-plumbed unvented cylinders

Horizontal unvented cylinders

Slimline unvented cylinders

Solar unvented cylinders

So why not browse the PlumbNation website HERE so you can find your perfect product today.