Closed system boiler in open vented system

Discussion in 'Plumbing and Central Heating' started by DyerMaker, 23 Nov 2021.

  1. DyerMaker

    DyerMaker

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    Hi folks...

    Is there a way to put a boiler meant for a closed system into a vented system?

    I've heard of putting in a filling loop instead of a filling tank... is this a good idea?

    Appreciate some informed opinions.. Cheers :)
     
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    cross thread

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    If the system is suitable it can be converted to a sealed system that would accept a system boiler
     
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  4. DyerMaker

    DyerMaker

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    Don't really want to change my existing system, was just wondering if there's a way to keep the boiler "happy" so-to-speak so it works within a vented system.
     
  5. oldbuffer

    oldbuffer

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    1. Its not really possible. A sealed system relies on the primary side (radiators, heating coil) to be pressured to around 1.3 bar.
    2. With a vented (unsealed) system you would have a feed and expansion tank in the loft, say, with the boiler in the kitchen. With most houses having a ceiling height of around 2.4 metres, you have the F&E about 5 metres above the boiler. One (first) floor at 2.4 metres, say 1.5 metres from ceiling to boiler in kitchen, and perhaps 1 metre from F&E to first floor ceiling. This is roughly equivalent to a pressure of 0.5 bar, so not really enough to pressurise the system.
    3. Going the other way round (vented to sealed) is much easier.
     
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  7. ianmcd

    ianmcd

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    your post is very confusing, do you mean you have an open vented boiler and want to replace it ? you can still buy open vented boilers
     
  8. DyerMaker

    DyerMaker

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    Thanks... just to play devil's advocate... what if a 1.3 bar pressure relief valve was put on the vent pipe?
     
  9. DyerMaker

    DyerMaker

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    Sorry for confusion... I'm thinking of adding a gas boiler to an existing solid fuel system... and weighing up the options of what's available. It sounds like.. so far anyway.. that I'd be best finding a boiler suitable for a vented system
     
  10. ianmcd

    ianmcd

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    yes you get boilers that are suitable for a vented system, tend to be a bit more expensive as not so many sold but saves you pressurising the system
     
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