Unvented Hot Water Cylinders

We offer unvented hot water cylinder installation or replacement services in Sonning Common, Henley on Thames, Wargrave, Caversham and the surrounding areas of Oxfordshire, Berkshire, and Buckinghamshire.


Once seen as a specialist product that was to unusual from the tried and tested gravity fed system to install, unvented or mains fed cylinders are by far the most efficient and most reliable hot water storage solutions available now. For any size property, single cylinders or multiple cylinders can be installed. A major benefit of a correctly installed system is having high pressure balanced mains fed hot and cold water at all outlets. Tap Tight Plumbing and Heating Engineers have been G3 registered installers, qualified to install unvented systems for nearly a decade.

What is an Unvented Hot Water Cylinder?

Unvented Hot Water Cylinder

Unvented cylinders, sealed systems, also know as mains fed cylinders, provide much better mains pressure throughout your property, traditional vented cylinders need a large gravity supply tank in the loft, supplying a cylinder below, that needs to have a vent back up into the tank for when the hot water expands or overheats, this limits the amount of water pressure as the higher your supply gets and the closer it gets to the supply tank the less water pressure you have. This is normally why properties with vented tanks cannot have showers or have showers with very poor pressure. Unvented, or sealed system, also know as mains fed cylinders remove this problem, providing high pressure and flow mains water to each hot and cold tap.

How do Unvented Hot Water Cylinders work?

As water gets hot it expands, this is where the name comes from, as on old vented cylinders the hot water pushed up the vent pipe back into the supply tank, an unvented cylinder has no vent, as it is a sealed system, but it has 3 safety features, a combination valve that reduces the mains pressure to 3.5 bar, an 8 bar pressure relief valve in case this fails, a bubble top or expansion vessel to take up water expansion when hot, and an additional temperature and pressure relief valve for overheat faults.

Who should install your Unvented Hot Water Cylinder?

They must be installed by a G3 qualified competent person, as the danger to yourself and property for an incorrectly installed product is high. Properly installed unvented systems are very safe!

Our main supply partner is Megaflo, the market leaders in unvented cylinders and a bubble top design, which requires less serviceable parts, we also offer a more budget conscious Gledhill cylinder, both of which offer long term warranties.

Tap Tight Plumbing & Heating Engineers are G3 qualified so please call us for a free quote – 01491 905375.

See examples of our work with unvented cylinders

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Whether a private household, landlord or agent we are happy to provide you with the above services, and can also offer competitively priced Gas Safety and Landlord Certificates to ensure you meet current legal requirements.

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