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Experts in Hot Water Systems

We can service both open vented and unvented hot water systems, there’s a slight different between the two so it’s important to know which one you have.

An open vented hot water system has two tanks, one is a hot water storage tank usually located in an airing cupboard and the other is a cold water feed tank located at the highest point in the system, which is usually in the loft.

This system works by filling the feed tank in the loft with cold water from the mains supply, which then feeds into the hot water tank and is heated by an immersion heater or with a coil inside the tank, heated by a gas boiler. Open vented systems rely on gravity to build pressure and push water through the system, which as a result means open vented hot water systems normally have quite low pressure.

Open vented heating systems were the preferred hot water system for many years, up until the 1980’s when combi boilers were introduced. They are commonly found in older homes and are prone to some issues, such as the float valve in the feed tank sticking closed, causing the water levels to fall dramatically, they are also prone to contamination as the feed tank is open in the loft, and they also cannot work with a combi boiler so you would have to update your entire heating system when changing from a gas to a combi boiler.

An unvented or pressurised hot water system has a hot water storage tank that is fed directly from the mains water supply and therefore has a higher pressure. This system has no reliance on a tank in the loft to cater for expansion and venting, hence the name.

The system works by taking cold water directly from the mains water supply and heating it within the unvented cylinder, then storing it until required. The water can be heated by immersion heaters, a gas boiler through an indirect coil or increasingly by solar or other energy efficient methods.

These cylinders can be used for small use items such as under sink heaters or for larger domestic and commercial applications.

Unvented cylinders are generally very reliable but have several features that can give problems over time, which include pressure reducing valves, non-return valves, pressure relief valves and temperature relief valves, and failure of the heat source. It is a requirement of all unvented cylinder owners to have the cylinder inspected at least once a year.

Whatever your concern, please give our team of qualified experts a call on 0808 250 9949 to arrange a convenient time to investigate the issue.

Hot water systems repairs & replacement

Whether you have an unvented or open vented hot water system, our highly trained plumbers can maintain, repair and replace every aspect of the system to make sure it’s working perfectly.

Pressure issues

Water temperature issues

Leaking pipework

Faulty or broken systems

Hot water tank repair or replacement

Airlock issues

Strange noises coming from the system

Limescale build up affecting hot water

Water supply issues

How it works

Our local, professional plumbers are highly trained, fully insured and DBS checked, with an excellent first-time fix rate. So you can rely on them to get your plumbing problem sorted in no time.

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Frequently Asked Questions

Can I have an unvented hot water system fitted?

As long as you have space in the property with access to mains water supply. The ideal space would be in an airing cupboard.

Can I increase the water pressure from my open vented hot water system?

Yes, if you have low water pressure coming from the hot water cylinder, we can fit a booster pump which will improve the water pressure across the property.

Why is an unvented hot water system needed?

An unvented hot water system is essential in large properties to ensure mains pressured water is supplied to all appliances. It also removed the need for tanks in the roof space.

How often does an unvented hot water system need to be serviced?

An unvented hot water system should be serviced at least once a year to ensure it remains in optimal working condition.

Is there a problem with my hot water system?

A typical sign of a problem with your hot water system can be water passing through to the warning pipes. If this happens, it is likely the system is gaining too much pressure. Another typical sign you have a problem is lower pressure than normal coming from your taps, if this happens it’s likely you have an issue with your water supply.

What qualifies a plumber to work on unvented hot water systems?

Regardless of the work required, in you are hiring a plumber to conduct work on your unvented hot water system you should ensure they are G3 qualified. At Metro Plumb, we have a growing network of G3 qualified plumbers. Find your local plumber here.

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