Top-up bottle

[ShaunCorbs]

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.

What boiler you got?

 

[Mark K]

What boiler you got?

Vaillant 418 pro from memory, system boiler, flow and return outlets from the top. 18Kw.

 

[ShaunCorbs]

So that's fine I would install a nrv on the feed and then just install all you safety things minus the filling loop

 

[rpm]

Lever valve rather than gate valve? More reliable.

 

[Rob Foster]

Guys,

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.

I have read your plans very carefully, I would make an initial,observation that 65% of all sealed unvented systems leak and lose pressure so an unconnected Top up bottle could be a pain, and mains water at pressure is very cheap.
Unless you are worried about wras regulation regarding seperation of drinking water etc. I can quote you chapter and verse if you need to know
I am a heating designer so can see where you are coming from.
But why design problems in ?
I also fail to understand the motivation behind your project
So,perhaps you might elabourate (they can’t touch you for elaborating I do it )
Rob Foster

 

[Mark K]

So that's fine I would install a nrv on the feed and then just install all you safety things minus the filling loop

Thank you, great to have it confirmed. I add the filling loop later if I want to, or decide to do away with the header tanks to free up loft space. For now the ball valve on the vessel manifold is a nice comvenient drain point .

 

[Mark K]

I have read your plans very carefully, I would make an initial,observation that 65% of all sealed unvented systems leak and lose pressure so an unconnected Top up bottle could be a pain, and mains water at pressure is very cheap.
Unless you are worried about wras regulation regarding seperation of drinking water etc. I can quote you chapter and verse if you need to know
I am a heating designer so can see where you are coming from.
But why design problems in ?
I also fail to understand the motivation behind your project
So,perhaps you might elabourate (they can’t touch you for elaborating I do it )
Rob Foster

Thanks Rob,

The house I bought in 1994 was a small cottage, with no heating or hot water. I installed a boiler in the cornerof the 8' x 8' kirchen and, because there was no space I put the cold water tank, f and e tank, hot water cylinder, pump and S plan valves in the loft.
Primary flow went from the boiler, past tje vent pipe, past the fande through the pump and into the S plan valves.
The house is 2.5 times the size now and what was the cornerof the kitchen is the middle of the lounge and the boiler is in the garage, which didn't exist back then.
I have added two radiators in the, now, kitchen, (to replace electric underfloor heating) and connected into the f and r primarys for 2 reasons. First, it saves ripping the house apart and second, so I can have it as a seperate zone. With the pump in the loft, A, the heating or hw would need to be on to get circulation so it could only be a zone that could be off, not on by itself. B, the circulation could/would bypass the boiler. So I moved the pump to the flow directly above the boiler. But that puts the pump before the vent and f and e connections.
Again, moving those involves pipe runs in the decorated part of the house, so I decided to make it a sealed system.

It's almost just an acedemic interest thing for me to know if I can use the f and e tank as a top up bottle, permanemtly connected via a nrv.

I have oversized the expansion vessel slightly to reduce the pressure rise and only filling to atmospheric pressure via the top-up bittle seems a good move too.

 

[Mark K]

Ok Mark, point made now stop poking the bear eh?
(pun intended lol)

Yes, agreed, I was quite upset. Calmed down now.

 

[Mark K]

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

That is my understanding, also, as the boiler has top outlets, the chance of damaging it, or causing a danger, from running dry is minimal, unless the boiler itself fails, then it's damaged anyway, and that's no different to a vented system.

 

[Mark K]

Lever valve rather than gate valve? More reliable.

Indeed, but there is already a gate valve on the outlet from the F and E tank.

I know, I know, there shouldn't be.

 

[Rob Foster]

Yes, agreed, I was quite upset. Calmed down now.

Ok so we are all back on track
Now, Imwill,look at this again when I get gnome
Rob Foster aka centralheatking

 

[Mark K]

Ok so we are all back on track
Now, Imwill,look at this again when I get gnome
Rob Foster aka centralheatking

Hi Rob,

This explains a little better. Excuse my technical drawing, a bit rusty these days.

Cheers,

Mark

 

[Gasmk1]

why not fit one of these in plave of the tank and set at 1/2 bar you can get them with a guage easy to do

Emmeti UK - 00200514 - 1/2" MBSP x FBSP - Automatic Filling Valve - 00200514

 

[SimonG]

Personally I would go filling loop and do away with tank and just pressurise to half a bar.

 

[Mark K]

why not fit one of these in plave of the tank and set at 1/2 bar you can get them with a guage easy to do

Emmeti UK - 00200514 - 1/2" MBSP x FBSP - Automatic Filling Valve - 00200514

Never seen one of those, every day is a school day. Thank you.