DIY Doctor

Shower problem

Postby MB28 » Sat Dec 04, 2010 8:06 pm

I have just had a new bathroom fitted. I have a separate shower unit (which I had in the last bathroom) this was power by a twin impeller pump, which is in the loft and the water comes from the cold water tank (located in loft) and hot water tank (located on same level as shower). My old bath and sink had the cold water coming from the mains and hot from the tank.

After having the new suite fitted the hot water pressure was far to low on the sink, bath and shower was just a trickle. My plumber suggested a single hot water impeller pump located next to the hot water cylinder which was installed and gives great hot water pressure to the bath, sink and shower. The shower would only stay hot though, so he installed a single impeller pump in the loft for the cold water to the shower only, which gives great pressure to the shower, HOWEVER......a problem occurs when he tried to mix the temperatures. One pump seems to switch the other off to there is a toing a throwing of pumps making the water flow very uneven, i.e hot - cold - hot - cold, you can hear the pumps shutting on and off in turn.

does anyone have any idea's of how I can achieve equal balance for the shower?

I have a thermostatic shower valve, the hot water pump is 1.5 bar 22mm, the cold is 1.7 bar 15mm. The plumber has suggested either trying the cold water coming directly from the cold tank, or mains.

If anyone can suggest and advice I would really appreciate it, I am so worried that the bathroom I have spent a lot of money on will not have a decent working shower.

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Simply Build It

Postby plumbbob » Mon Dec 06, 2010 10:43 pm

The most obvious point is the shower MUST be run from a single twin impeller pump so the supplies are always balanced.

If need be, a further single impeller pump can be installed for the hot supply to the sink and bath.

I might add, if the old bath and sink hot worked ok but the new ones don't then it is possible you have bought/been sold the wrong taps.
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Postby CathyA » Sun Jan 09, 2011 9:35 pm

[quote= wrong taps.[/quote]

I wondered what you mean by 'wrong taps'. I have just had fitted (by an amateur) a mixer tap shower thingy, and although it seemed to work OK when he fitted it, the hot water doesn't come out any more (nether from shower rse or bath tap). I have been browsing everywhere online to try and find the cause/solution. I don't want to turn it off and drain the header tank etc until I know what I'm looking for - or whether I will need to remove the new gizmo and just put my old taps back on. How would I know if my tap is right or wrong?


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Postby plumbbob » Mon Jan 10, 2011 8:43 pm

Some taps, particularly cheaper types imported from abroad will only work with high pressure systems such as hot water supplied by a combi boiler.

If connected to a low pressure system ie, a hot water system which is supplied from a header tank, these high pressure taps will only dribble or at the best only run slowly.

If your taps have worked in the past, then this will not be the cause. An airlock is far more likely possibility.
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Postby robsmith25 » Tue Jan 11, 2011 9:24 am


I too have had a 'Bristan Qube Inline Vertical Shower Pole with Integral Diverter' shower fitted 4 months ago that worked great for two months, now it goes hot and then cold each time we use it. The shower has had the filters inspected by the chap who fitted it and there appears to be no problems and it is not a hard water area. We have a valient combination boiler less than 4 years old down stairs and the shower is up stairs so no water tank. Would anyone have any ideas what the problem could be or if there are any existing issues with this particular shower. I have a bristan engineer coming out in a few days and just want an idea before they come.

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