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  • Do Unvented Hot Water Cylinders Need An Annual Service?

    29th December 2018 | News | steveduval
  • Unvented Hot Water Cylinders

    First I will explain what unvented hot water cylinders are.

    How it differs from a vented hot water cylinder.

    Most properties in the United Kingdom were built with hot and cold water storage tanks.

    These tanks supplied hot and cold water to the bathrooms and the hot water to the kitchen.

    Nowadays it’s becoming very popular with homeowners to 

    convert the cylinder over to an unvented cylinder.

    So what are unvented hot water cylinders?

    Unvented hot water cylinders work by using the incoming water mains to supply water to all hot outlets.

    Whereas the vented hot water cylinder relies on a cold water storage tank to supply it with water.

    This is normally called low pressure.

    The incoming water mains need to have a minimum pressure of 1.5 bar for the cylinder to work correctly. 

    The higher the incoming water pressure the better.

    For an unvented cylinder to work correctly the incoming water 

    supply pipe needs to be a minimum of 22 m, the bigger the better.

    Every unvented hot water cylinder is supplied with a pressure regulator set which is normally set to 3 bar.

    So if you have an incoming water pressure of 6 bar the 

    regulator will reduce it down to 3 bar to all outlets.

    The regulator is connected to the mains water supply pipe, 

    it has two connections one to supply the unvented hot water cylinder. 

    The other is to connect the cold supplies, 

    this will give an even water pressure at all outlets for both hot and cold.

    If you decide to convert over to an unvented hot water cylinder, 

    then the cold water storage tank, normally

    located in the loft can be removed. 

    All the cold water outlets from the tank will need to be connected to the 

    water mains through the regulator.

    These unvented hot water cylinders still works in the same 

    way as the vented cylinder. 

    water is still heated via the boiler or immersion heaters, 

    the only difference is the water pressure.

    So Do I Need an Annual Service?

    The answer is simply yes.

    Just like your gas boiler, the unvented hot water cylinder needs to be 

    checked to make sure it is safe and working correctly.

    So What Needs To Be Checked?

    Every cylinder will have some form of expansion vessel. 

    This could be internal or external and needs to be checked at least once a year.

    The expansion overtime will deplete and needs to be reset.

    The cylinder will also be fitted with a safety valve called a 

    temperature and pressure relief valve.

    it will need to be checked to make sure that it is

    working correctly and doing what

    it is supposed to do.

    All unvented hot water cylinders can only be fitted by a registered person by law.

    If fitted incorrectly it could become a potential bomb. 

    just check out the videos on YouTube to see what could happen should something go wrong.

    It’s just as important to have the unvented cylinder serviced as

    it is to have your central heating boiler serviced. 

    Always be safe and have the annual check.