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    Boilers Unvented Hot Water Cylinder
  • What is unvented Hot Water?

    The unvented hot water cylinder is now becoming very popular with homeowners when they start carrying out home refurbishment.

    The reason being is they are economical to run, high-pressure hot water at the taps and showers,

    no need for the noisy pumps anymore, and also no need for the cold water storage tank in the loft.

    So when the freezing winters arrive no need to worry about frozen pipes.

    With the unvented hot water system, you need a good incoming cold water mains pressure,

    the minimum pressure you should have is around 1.5 bars. 2-3bar is the recommended pressure required by most unvented hot water cylinder manufactures.

    There are many makes of unvented hot water cylinders on the market today to choose from.

    In my opinion, the Megaflo is probably one of the best around, but it comes at a cost.

    The reason I say the Megaflo is if the incoming water pressure is not so good,

    once the tank is full it seems to help boost the water out to the taps.

    The Megaflo has an internal expansion gap,

    where most other makes have an external expansion vessel and this help boost the pressure.

    Unvented hot water cylinders and any unvented systems have to be installed by a registered unvented engineer.

    This seems to get overlooked by most homeowners, as it is not promoted like Gas is with Gas Safe.

    The unvented hot water cylinder comes with safety devices fitted as standard, but just imagine, if they stopped working.

    I know it’s a long shot, but it can happen.

    The water inside starts to boil where does the expansion go?

    As the water heats up it starts to turn to steam, you now have a steam bomb on your hands.

    When I trained for unvented hot water, we were shown a video of an unvented hot water cylinder that was about to explode.

    The cylinder was in the basement of this house, and as it took off it went through 3 floors, then the roof and still travelled

    50 foot in the air, that’s how dangerous these things can be.

    I know it’s a long shot for this to happen, but we have so many different types of unvented hot water systems these days, big and small units,

    that it’s so important only to let a registered installer carry out any work on these units.

    Unvented hot water cylinders are still expensive, but they are slowly coming down in price, which is good for the homeowner wanting to convert over.

    If you are carrying out a full refurbishment of your property then the cost would probably be the same as if you were to install a cold water tank, hot water tank and booster pump.

    The unvented hot water cylinder will save you money on your energy bills because they are well lagged with insulation, also you don’t lose any heat up the vent pipe as you did on the old vented system.