pump position relation to hot water cylinder Drainage and wastage systems and plumbing help, advice and answers

[farney]

I am new to this site so I appreciate this may be a stupid question but is there a rule of thumb that dictates the position of the shower pump in relation to the hot water cylinder. Mine is approx 1 metre away but very close to the shower mixer say 350mm Have I got this the wrong way round as pressure falls off at shower head after 20-30 seconds of firing up the shower. In and outlets to pump are 22mm as is cold feed to HWC. At present there is a Surrey flange in position but Techflow don't like those. Does any one have any experience of the top entry Techflange and if so would it make any difference. All help will be appreciated

[stoneyboy]

farney,
With such a short distance between the tank and shower the position of the pump should not matter. The surrey flange should work fine - the pump should be connected to the side exit rather than the top one.
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[farney]

stoneyboy

many thanks for that, I have actually replaced Surrey flange today with a top entry Techno flange and so far the shower works fine but the critical point will be tomorrow morning just after a new batch of water has been heated which is when I get a fall off of pressure or an ingress of air all todo with aeration I suppose. As you say I would have thought the Surrey flange should have worked. I will report back later

[farney]

well the Technoflange works better but here's the thing. . .run the bidet hot, the basin hot and the shower hot all at the same time and guess what? a great splurge of air and then all is well. the shower will now rip your skin but where is the air getting in. Directly leaving the HWC is a elbow and then a slight incline to the vent before going vertical, I am going to change that to 45 degrees before going vertical to the vent but any other thoughts will be more than welcome. Thanks

[stoneyboy]

farney,
Thanks for the feedback. From your description look for a horizontal section in the vent pipe (probably in the loft) I suspect vented air is collecting here and when you turn everything on this is sucked into the pump. Once the slug of air has been removed the vent pipe will be full of water.
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[farney]

stoneyboy

Yes thanks for that, will try and reduce all horizontals to a minimum will report back later, rather hot in the loft at present.