Shower Pump Wont Pump much water

Discussion in 'Plumbers' Talk' started by Joiner Will, Mar 17, 2019.

  1. Joiner Will

    Joiner Will New Member

    Hi Everyone,,,, Im lost and almost ready to jump off a bridge with this problem. I will explain my problem and what I have done and any suggestions would be most welcome.
    when I turn the shower on, the flow is great for about 2minutes, then the pump noise changes to a higher pitched noise, and its spluttering and hardly any water is coming out, when I turn the valve between hot & cold the pump makes an array of different noises, the cold flow is a little better than the hot but it really sounds like I have air in the system, its as though the cylinder is emptying below the surrey flange, then it seems that's when the air comes in, I have two tanks above in the loft which both empty togeather but I don't really know, I don't have any blockages in the filters as its great for the first couple of minutes, I was thinking do I change to a Negative head,,, any ideas

    1 Installed 1.5 Grundfos watermill shower pump, twin imp, positive head
    2 its located on the floor at the base of the cylinder
    3 I have fitted an additional tank in the loft
    4 I have fitted a surrey flange to the cylinder
    5 from the top of the shower head to the bottom of the tanks in the loft is approx 600mm

    I appreciate any advice form anyone, I just don't know what else I can do
  2. andy48

    andy48 Active Member

    1. It sounds as if its being starved of water, probably of hot water.
    2. The pressure to force the water out of the hot water cylinder comes from head of water between the cold water storage cistern(s) (CWSC) in the loft and the top of the hot water cylinder.
    3. You say you have fitted an additional CWSC. How has this been piped. With two CWSCs you should have the mains cold going into one, the feeds to HWC and domestic cold from the other, with the two cisterns linked. Without this arrangement the water in one can go stagnant.
    4. Photo's of the loft cisterns and the airing cupboard showing all tanks and connections would be useful.
  3. Joiner Will

    Joiner Will New Member

    Thank you for your reply, it looks like the original water tank has the ball cock in, mains water feed and pipe down to HWC and vent pipe coming up. the new tank has just been fitted alongside the original and joined together by a 22mm pipe, it looks like both tanks empty out together and fill up together, I see what you mean, the new tank dont seem to have much to do, apart from holding extra water, I wonder if I were to lift the old tank up, then fit the new one below it, wold that be better, but im not sure how I would go about doing this. cheers
  4. Heat

    Heat Well-Known Member

    Surely it is as simple as running the shower and going up to the cold tanks with a torch to watch if they quickly drain?
    I would doubt if they do, unless terribly small tanks or badly connected.
  5. Joiner Will

    Joiner Will New Member

    I did, and both tanks drain the same speed, seems to be plenty of water but not much humph, if you get me
  6. ecoplumbing

    ecoplumbing Active Member

    Have you checked the gatevalve from the cold water tank to the cylinder? Maybe this isn't fully open or as you've been turning it on/off it's broken. To me it sounds like a partial blockage and the cold water isn't filling the cylinder quick enough
    Heat likes this.
  7. SteveMJ

    SteveMJ Member

    I'll add the caveat that I am amateur (as regards plumbing). I changed my gate valves for full flow ball valves for the feed for both my hot and cold water from the loft tank CWT. This was because the gate valves were many decades old and would hardly operate; just enough to turn almost off and almost on.
  8. Joiner Will

    Joiner Will New Member

    Actually I think both andy48 & ecoplumbing are right, seems it could be not enough water to the Cylinder, im thinking of taking off the gate valve,as that has been there for 20 years and replacing it with a ball valve like SteveMJ suggests. I was also thinking of trying to lift both water tanks up, as I think I only have 600mm from shower head to bottom of tanks... any ideas the best way to plumb up both tanks, I know andy48 suggested it should be mains in and water out of the second tank, makes sense to me, but how would I do it, with ball cocks etc, would I need one in each tank, best method to have a better pressure to my shower pump would be great, as sometimes the shower wont kick in, so it could well be the pressure. appreciate any help
  9. ecoplumbing

    ecoplumbing Active Member

    Water main inlet/ ball valve should be connected to 1st tank which is joined up to 2nd tank. 2nd tank has all the oulets which means fresh water is constantly being pulled through from the 1st tank. No need for a 2nd ball valve in the 2nd tank.
    2 options regarding the pressure. Lifting the tanks would certainly help your positive pressure pump but personally rather than doing all that work moving pipework. new timber etc, just replace pump with a universal one, ok they cost more but it would save all that work
  10. Joiner Will

    Joiner Will New Member

    Thank you will try and move the tank at the weekend,as the pump is new, will change the gate valve too while im on with it, thank you all for your assistance, will keep you posted if it solved it or not
    ecoplumbing likes this.
  11. Severntrent

    Severntrent Active Member

    What happens if you turn the shower on with the control valve just set to cold water, and similarly if you set it to run hot. What capacity is there in the 2 cold tanks
  12. Joiner Will

    Joiner Will New Member

    hi severntrent
    cold water,,, pump kicks in really good for about 2 mins,then flow very low
    hot water,,, pump kicks in and that too is really good, but after about 2 mins it goes to almost zero water and its coughing and spluttering, as though there is air in it. hope this makes sense to you
    thank you
  13. Joiner Will

    Joiner Will New Member

    Oh the tanks are the big ones about 800mm x 600mm, maybe 50 gallon each I think, but I may be wrong

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