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Top-up bottle

Discussion in 'Water Regulations' started by Mark K, Dec 3, 2018.

Discuss Top-up bottle in the Water Regulations area at

  1. Mark K

    Mark K Member


    I am just changing my own heating system to a sealed system (not the hot water, just heating) because I added a circuit and needed to move the pump, now the Vent and F and E tank are on the pumped side of the pump.

    Expansion vessel sized and fitted, and open vent sealed off with a bottle air vent, (or will be) but I have 2 questions...

    1, can I use the F and E tank as a "top up bottle" instead of using a mains filling loop? Checking my understanding...I think I can, so long as I can fill the system, then seal it, I don't see an issue.

    2, If so, can I simply use it manually, with a gate valve or do I need to fit a non-return valve and have automatic top-up, is this the best of both worlds, or does it just mask leaks? I think I can do either.

    Two advantages as I see it...

    1, minimum pressure, as only enough to fill the system is needed.
    2, less work!! never a bad thing!

    Thank you.
  2. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Know you need a proper filling loop and pressure gauge in with a built-in non-return valve the mains water I think your question shows you don’t really know what you’re doing have you thought about safety devices
    • Agree Agree x 1
    • Disagree Disagree x 1
  3. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    You can do but you need a nrv on the feed pipe also where's your blow off going ?
    • Agree Agree x 1
  4. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Just wouldn’t risk a pressurised system on an NRV not failing
    • Agree Agree x 1
  5. Mark K

    Mark K Member

    Yes, there is a 3 bar pressure valve, in the garage where the boiler is, piped to outside, it's connected into the system with no valves along with the expansion vessel. There is a pressure gauge fitted at that point, next to the boiler.

    I could connect a mains filling loop in at that point, but diagrams in the boiler MI show sealed systems with a top-up bottle, rather than a "proper mains filing loop", perhaps as I "don't know what I am doing" you could explain that to me....or explain why the boiler manufacturer doesn't know what he is doing???
    • Agree Agree x 1
  6. Mark K

    Mark K Member

    I have fitted a complete system, with expansion vessel, blow off valve, piped to outside pressure gauge and a connection for the mains cold water filling loop.

    My question was simply, can I fill that system from a top-up bottle, rather than the mains?

    The boiler MI shows that I can.

    The NRV on the F and E tank (top-up bottle) is to seal the system, not as any safety device.
  7. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    You never mentioned that you’d fitted safety devices and stated yourself that you were looking for the easy route and because of the attitude on a forum where experts give their opinion free of charge I’m out!
    • Agree Agree x 2
  8. Mark K

    Mark K Member

    My attitude?
  9. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    The “” marks you seem to forget you’re on a forum asking what to do which implies that you don’t know? Correct? Anyway bye
  10. Mark K

    Mark K Member

    An expert wanting to help may have said "have you thought about safety devices?" Someone with a bit of knowledge trying to big themselves up would have said "have you thought about safety devices, your question shows you don't really know what you are doing". I didn't say I hadn't piped it up in garden hose either! Your attitude stank. I was looking for answers based on experience so I can understand, and not just plumb by numbers. Your answer about needing a filling loop instead of answering my questions shows that is what you do, so I will wait for an expert. Thanks for your input though.
    • Optimistic Optimistic x 1
  11. rpm

    rpm Trusted Plumber Top Contributor!!

    Looking at your post in introdutions I can see that you are not the average diyer looking to save money and you are asking the Q to be sure of what you think will work.
    Sometimes the odd " or ! can change the dynamics of the conversation so perhaps a cooling off period here would help matters and the thread can continue later?
    • Like Like x 1
    • Agree Agree x 1
  12. Mark K

    Mark K Member

    Exactly, Shaun's reply was more what I would expect from polite society.
  13. rpm

    rpm Trusted Plumber Top Contributor!!

    Ok Mark, point made now stop poking the bear eh?
    (pun intended lol)
    • Funny Funny x 1
  14. Mark K

    Mark K Member

    Thanks Shaun,

    I have put the expansion vessel, supplied as a kit in the garage, connected directly to the boiler return. It is fitted with a 4-way manifold, into which is connected, the vessel, the boiler return the blow off valve and a connection for cold fill with a ball valve.

    The system is not new, so I want to keep pressures as low as possible, but I am getting some pump-over because the vent and F and E tank are now on the positive side of the pump. It's major work to change that because of the pipework layout.

    I would think that once the system is full and the top-up bottle disconnected, nrv in action or gate valve closed, or the mains filling loop disconnected, that the system would not know any different.

    The gate valve would be just like the combined nrv/ball valve that came with the kit, but just a nrv would give automatic top-up, like a vented system?

    Just looking for any reasons why I am wrong.
  15. snowhead

    snowhead Well-Known Member

    Using the existing F & E tank how would you achieve the initital system pressure?
    Scrap that question , it was open vented so won't have a minimum requirement.
    Last edited: Dec 3, 2018
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