HW vent pipe

[Shift]

Two days ago I installed 140 l indirect cylinder and 50 gallon loft tank, since installed I them I have a small amount of air coming out of the HW taps. The only differences from the old system are the increased size of the tanks, a surrey flange (ready for shower pump with valve closed) and the HW vent pipe which I have configured like picture below. Have I created the problem configuring the vent like this and should it go vertical from the HW.

 

[kevplumb]

draggin air down the vent

 

[Shift]

Thats what I thought might be happening, here's a photo as picture isn't clear. Any suggestions how i could rectify my mistake

 

[stevejohnson]

450mm min offset from top of the hot water cylinder, then should run horizontally (with a slight rise) - then a tee, up to the vent and downards to the ground, before running off to the hot water taps (draw offs).

 

[Shift]

Thanks Steve would this be ok

 

[stevejohnson]

yes that looks correct - make sure the offset before the tee is a min of 450mm though, or you will lose heat straight up the vent . try and make sure the vent pipe is as straight a run as possible (if space). but should be fine that way.

the flange for the shower is fine... did you buy a 3/4" to 22mm/15mm connector for connection of the pipe to the pump?

 

[Shift]

Thanks again Steve, if I go straight to the vertical it only measures 270mm so will it be ok to put in a 90 degree bend to gain the extra length required.
Yes I did buy a 3/4" to 22mm fitting for the pump pipe

 

[ChrisR]

No need to do much at all - a couple of couplers and unbend the pipes a bit so there's a slope for the bubbles to go up...:

 

[GPlumb]

+1 to what ChrisR says.

 

[Shift]

Thanks for the input ChrisR and Gplumb but would it be better to do as Steve has recommended particularly the 450mm offset to avoid heat being lost through the vent. It's not to much trouble to change layout and I would prefer to achieve as near as possible to the optimum set up.

 

[D_Hailsham]

make sure the offset before the tee is a min of 450mm though, or you will lose heat straight up the vent.

What is the theory behind the magic 450mm?

 

[Shift]

Not sure exactly why a minimum of 450mm maybe Steve can enlighten you, mine now measures 410mm after reconfiguration today, no air's entering the HW so I'm

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• Shift
• 25 Nov 2008
• 1

Thanks for the advice.

 

[D_Hailsham]

Not sure exactly why a minimum of 450mm maybe Steve can enlighten you

I wasn't expecting you to know the answer - if you had, you wouldn't have asked your question in the first place.