Pump and vent pipe

10 Jul 2006
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United Kingdom
I think this is a stupid question but I can't find an answer elsewhere.

Need to install a pump for a new shower we're putting in. 3 storey house. HW Cylinder in airing cupboard on 2nd floor. Shower will be installed in an existing bathroom (sink and bath only) on 3rd floor. Hot water from floor 3 is piped up from cylinder on floor 2. Cold for floor 3 is tapped off mains on its way up to the tank in the loft. Running new pipework will be extremely difficult but existing pipework accessible at both ends.

Plan is...

1. Install single HW pump (Stuart Turner) next to cylinder in airing cupboard. 2 bar.
2. Install Pressure Reducing valve on cold in airing cupboard as it heads up to 3rd floor. Reduce to 2bar (we seem to always have higher than that). Both Stuart Turner and Grohe (shower valve mnfr) seem to think this is ok.
3. New Surrey flange and dedicated feed for pump.
4. Tap into HW 22mm a it goes upstairs. Attach to pumped outlet instead of to cylinder (current arrangement).

This will pump the whole bathroom on floor 3 (sink and shower - there is nothing else) upstairs.

The arrangement means I can work with existing pipework, which I can access in the airing cupboard or in the stripped out bathroom.

My main question is whether this arrangement causes a problem with the vent pipe. The pumped outlet heading upstairs goes to the bathroom and then (presumably) carries on up to vent. If I pump this, do I cause a problem with the venting arrangements?

Any help gratefully received.
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You cannot have an open vent on the outlet of the pump, for many reasons. You will need separate pipes for the vent and the pumped hot.

The mains cold (+PRV) and pumped hot isn't ideal, but can work.

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