F&E vent pipe

[PrenticeBoyofDerry]

Can some one please confirm the minimum height of the vent pipe above the water level of an F&E cistern and any information to back this up with.
Having a little debate about this with colleagues.
PS I understood it to be 450mm!

 

[sooey]

I used to know that one a long time ago....as far as I remember it's 40 mm a metre of head height plus a couple of hundred mm. So it sounds about right for a two story house but not a three.

 

[PrenticeBoyofDerry]

Is that not the calculation for the CWSC Vent Pipe rather than F&E.
(H X 0.4mm) + 150mm
Height of pipe from cylinder cold feed inlet to warning pipe multiplied by 0.4 per metre plus 150mm

 

[onecog]

It is 450mm min above water level when cold.
That is the highest point ie the bend.

 

[PrenticeBoyofDerry]

It is 450mm min above water level when cold.
That is the highest point ie the bend.

Thanks for that onecof.
May I expand ? Not a pun by the way

So cold water only, not allowing for any expansion of water in F&E cistern?
Is there anywhere you could point me to where this requirement can be clarified? A link or something within water regulations guide, cheers.

 

[sooey]

Is that not the calculation for the CWSC Vent Pipe rather than F&E.
(H X 0.4mm) + 150mm
Height of pipe from cylinder cold feed inlet to warning pipe multiplied by 0.4 per metre plus 150mm

Sorry, yes it is.
I think the 450 figure that's used for the vent on the f&e is a recommendation derived from that though. If it was a requirement you wouldn't have combined feed and vents.

 

[onecog]

I can't point you to any information on it but as a time served plumber that's what i was taught 37 years ago

 

[PrenticeBoyofDerry]

Thanks for the input chaps.
It's something I have in my head from somewhere, not sure how or why. But was brought up in conversation last week, so I put my two penneth in to the mix but would like to know where and why this was/is required, so can back up my comments.
If memory serves me, something to do with pressure surges of the pump?

 

[sooey]

Digging the books out now.
Do you mean this taken from one of the Treloar books.

The cistern must be placed in such a location that it will not be affected by the position and head of the circulating pump. A minimum dimension of the maximum head developed by the pump divided by three needs to be maintained between the water level and the pump to prevent underwater movement in the f& e cistern.

 

[PrenticeBoyofDerry]

I have seen somewhere that the specific measurement of minimum height is 450mm above water level of F&E cistern, but for the life in me!