Shower pump problems

[PaulWill]

I've recently installed a new bathroom on the same floor level as a gravity fed hot and cold water system. I've installed a twin negative head pump as per the photo but still have problem with the hot water running through the pump. Cold water through the pump is fine. I've got a surrey flange fitted to the top of the hot water cylinder but the pump still sounds like it’s got air in the system and running the hot water at a much lower flow rate than the cold. Can anyone see any problems with the setup on the photo ? (from left to right: hot water in, hot water out, cold water out, cold water in). My thoughts are 1) That it may have something to do with the ‘T’ very close to the hot water pump outlet. 2) The feed from the hot water cylinder goes down, then slightly up (beside the brass elbow) then down again into the pump ? Any thoughts would be welcome. Thanks, Paul

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[footprints]

Hi Paul,
Certainly looks like a possible point to trap air on the elbow directly above the hot inlet, cutting back the pipe above the copper elbow to move the elbow up a bit to give air a chance to clear is certainly worth doing.
Or of course you can re-jig the pipe to run under the 15mm and cut back the pipe connecting to the pump.

Regards,
footprints

 

[PaulWill]

Now also wondering if the surrey flange is the wrong flange. Should I have fitted a Warix flange instead. Whats the difference between the surrey and the warix ? I've read somewhere the surrey can restrict the flow ? Want to avoid drilling a hole in the side of the cylinder for an essex flange if at all possible.

 

[hazetimesfive]

its all run in plastic, which is more restrictive than copper, lots of elbows instead of nice sweeping bends, open vent in plastic.. wtf..

the flange is the least of your worries.. I would be ashamed to charge money for an install like that.

 

[footprints]

Just going back to basics for a moment I can't see the isolation valves on the push fit connections are they fully open?
Have you disconnected the shower and checked the flow rate to the bathroom with a temp hose into the bath or a bucket?

Surrey flanges do restrict slightly more than Essex not sure about Warix, I thought the main difference was that you can swivel the Warix around to any position instead of being stuck with wherever the thread on the Surrey tightens.


It looks as though perhaps you have two showers running of it, there seems to be one backing onto the cylinder I would be suprised if any restriction the Surrey gave had much effect on a run that short.

Can't say I'm a fan of plastic either, I too would like to see the open vent in nice rigid copper, I only use it as a last resort myself, but I doubt it's causing any real problems with regard to flow, born out by the fact that you say the cold which has a similar route is ok.

 

[Tipper]

Mine used to do that at my last house but one.

It seemed to be due to a slight upward run of pipework between the cylinder and the pump causing an air/vapour lock. Also if the tank temperature was high the pump seemed to vapour lock more.

Make sure all pipework from cylinder to pump has a downward gradient so that any air/vapour can vent away up the pipe. It was sometimes cured by turning the shower to hot and full volume to get the flow moving before setting the desired shower temperature.

(Oh and I think it's a 'Warwick' flange not Warix. As in Essex and Sussex!)

My pump ran two thermostatic showers with no problem at all.

 

[PaulWill]

Thanks for all the feedback, some usefull points to try. On the general arrangement of plastic pipes I'd have to agree that its all a bit of a mess. Wish i'd taken that up with the plumber at the time. Unfortunately there are no isolation valves on the connections apart from the connection between the cold water tank and the cold water inlet to the pump. There is a mixer tap/shower head on the bath that's fed from the pump which has good cold water flow rate and bad hot water flow rate when everything else (main thermostatic shower which you can see the back of in the photo and sink taps are turned off).

I will definitely try re-routing the pipework to ensure the hot water feed to the pump follows a continueous downslope. Whilst I'm at that I'll also turn that 'T' on the hot water pump outlet 90 degrees anticlockwise to ensure the pump isn't pumping against a pipe wall in the T. In regard to the surrey flange, the instructions for the pump actually states not to use one and use a warix or esssex instead, so I'll try fitting that also. The warix will also allow me to feed off from the correct side of the cylinder instead of the surrey (ie less elbows)

Hopefull some of these will fix it.

 

[footprints]

Sorry Paul,
I had it wrong I assumed it was a DIY job, if your plumber did it, why not chase him up?
footprints

Ps If you are prepared to do it an essex flange is perhaps the best option several bits of advice on the net about fitting one, but try your other ideas before altering the take off from the tank might save a lot of unneeded aggro

 

[Nige F]

I`ve not commented because I thought it was a Novice DIY job That is un believable if the Clown had the nerve to even think he was a Plumber PS a Sussex flange is brazed into the side of a copper cylinder