One way valve help or advice

Orkatec

Hi
I have very little head between my Hot water tank and header tank.
I wish to fit a shower pump but I am worried I might suck air in to the system through the expansion vent.
Would it be possible to fit a one way valve on the expansion pipe to prevent this or dose any one have an alternative suggestion.

Kim

DVardysShadow

Valves or any obstruction in expansion pipes are a big NoNo. Expansion pipes are there for safety and when they need to blow off, they need to be free.

You need your draw off from the top of the cylinder to be as low as possible above the cylinder top connection and you need the pipe from the header to the feed connection on the bottom of the cylinder to be as large a bore as possible. Ideally as big as the expansion pipe or bigger. Don't put in a smaller expansion pipe however.

keystone

Orkatec wrote: »

Hi
I have very little head between my Hot water tank and header tank.
I wish to fit a shower pump but I am worried I might suck air in to the system through the expansion vent.

You won't if you pipe it properly and site your pump in the right place. How much is "very little" Can you provide a dimensioned drawing of your setup please?

Would it be possible to fit a one way valve on the expansion pipe to prevent this............

Of course its possible to do it. Should you do it? No, No and thrice No.

....or dose any one have an alternative suggestion.

Yes pipe it correctly and site the pump properly.

Cheers

Edit: Oh - DV got there first.

ormus

as above.
never ever put any restriction into the expansion pipe.

Orkatec

The bottom of the header tank is level with the top of the cylinder.
The draw off is as low as possible.
The feed from the tank to the bottom of the cylinder is open, would this not accommodate any expansion if the valve got stuck ?

keystone

Do you mean you have got one of these:


?

would this not accommodate any expansion if the valve got stuck ?

Which part of "thou shalt not fit any sort of valve on or obstruct your vent pipe" did you not understand?

Cheers

Orkatec

I understood it perfectly but I have only heard of one other guy who has the authority to say "thou shalt not".
Am I not allowed to question a statement given with out a reason to back it up ?

keystone

C'mon fella. You came on here looking for advice and three people in a row, independently, have told you that you should not do what you are proposing - there's a bit of a clue there. You respond to this by promptly banging on yet again about using an NRV and are surprised when you get the obvious reply. So do you want help or not?

Cheers

ariba10

You put a restriction in the vent pipe and you will make a potential bomb out of it.

Orkatec

The advice is most appreciated . Which part of "thou shalt not fit any sort of valve on or obstruct your vent pipe" did you not understand? Was not
This is the kind of response which puts people off seeking advice.
I assume you are or have been in the plumbing game, and I would ask you would you talk to a customer in this manner, I think not.

DVardysShadow

Orkatec wrote: »

... The feed from the tank to the bottom of the cylinder is open, would this not accommodate any expansion if the valve got stuck?

The Expansion Pipe is there precisely to defend against the circumstance that the Feed Pipe becomes blocked.

If you deliberately introduce a NRV into the Expansion, you start with that pipe effectively blocked and have removed your defence against the scenario which the Expansion Pipe is supposed to defend.

When an Expansion Pipe wants to blow, it may blow suddenly with some considerable force