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Discuss 2 showers 1 pump - problems ! in the Bathrooms, Showers and Wetrooms area at UKPlumbersForums.co.uk.

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  1. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    neg head pump and correct install of the shower pump is your only option
     
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  2. Ric2013

    Ric2013 Plumber

    What is your area? You never know: one of us may be local?

    My understanding is you're happy to have reduced pump life and sub-optimum flow as long as it works, which it did until recently.

    Do you mean you think the shower mixer unit is allowing air into the pipework feeding the shower mixer unit? If I understand your setup properly, that is very unlikely as the pipework is under the pressure of the head of water from the tank in the loft. I don't understand your baby analogy - a shower fitted with a separate pump does not suck!

    You haven't understood the terminology, I'm afraid. The shower mixer is not pulling water at all: the PUMP (whichever type you have, + or -) is pulling water from the cold cistern and the hot water cylinder and pushing it towards the shower. The distinction between the two types of pump is more in how they know when to switch on.

    A positive head pump is used to increase the flow to a shower that already flows under the pressure created by gravity. All the shower does is restrict how much water comes out.

    Where the bathroom is, say, above the cistern, opening the tap or shower valve would result in no flow at all and so the pump would not kick in. So you need a so-called 'negative head' pump that can hold the water in the pipe under pressure until the shower valve opens and then detect that the pressure is dropping and boom, kick in. A negative head pump would also be fitted to installations such as yours where there is very little flow available to be detected by a 'positive head' pump.

    Second column, left page: http://www.stuart-turner.co.uk/media/136776-SystemsPressurePumpsTypes.pdf

    If your installation is borderline, you may find that airlocks on the delivery side of the pump between the pump and shower or a shower mixer that allows very little flow at low pressure are restricting flow enough that gravity is not sufficient to clear them, but pump pressure is. So when you suck on the showerhead it is just enough to get the pump to switch on. The way that hot connexion to the cylinder is made it is quite likely that there will be a certain amount of air in the pipework between the pump and shower which could be a contributary factor.

    To be fair, this is an installation that may just about limp along (though you may be perfectly happy with the way it works) with a few tweaks, but either you will have to try making improvements one at a time, or you'll need to find a local plumber - we really can't diagnose over the internet when the fault appears to be a system design and installation fault and not an obvious product fault.

    Not trying to be harsh, but the point of being a plumber is (or should be) to understand all this stuff when you see it and to be able to make basic tests which are often quicker to do than explain to someone who isn't professionally trained via the net. Sadly a lot of bathroom fitters aren't actually plumbers and don't have a clue, and some plumbers are handymen and so you get the sort of problem you are now experiencing.

    I think you need to find yourself a good local plumber who is willing to try to diagnose faults. There is NOT a shortage of plumbers in this country, whatever people say. I had to laugh when a neighbour of mine (two doors down) was pleased to find I was a plumber and wanted me to quote on some work as she couldn't find a plumber (my van isn't signwritten); when I phoned her (she wanted me to phone before), she didn't reply and didn't return my call or answerphone message. Oh, and another plumber lives almost opposite, and has a signwritten van, but I digress...

    That said, I can understand a lot of us would run a mile - trouble with turning up to a job like yours is either a plumber does a quote which means pretty much rip out and start again, or s/he tries one thing then the next (and would need to be paid for each and every task because plumbers have bills to pay like all of us), some of which tasks may prove to be red herrings and a waste of your money, but all the same necessary to find the major cause. And the risk is (if someone doesn't know you better) that you'd then badmouth that plumber saying he took forever to do the repair charged too much etc etc. You can see why a lot of us would prefer to do a simple new installation on a fixed price and aren't keen to do repairs.
     
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  3. DripsnDropsBognor

    DripsnDropsBognor Member

    Oh the joys of having modern shower with check valves!
    Surrey flange 1st see if it makes any difference if not swap for negative head. I think the cold water stored in the loft isn't as high enough to go as far as the other shower with all the bends and fittings needed to get it there. As well as the hot water connection pulling in air through open vent due to the s flange not being fitted the first time around.
     
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