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Discuss recurring airlock in hot water feed to shower pump in the Bathrooms, Showers and Wetrooms area at UKPlumbersForums.co.uk.

  1. Big_Al

    Big_Al New Member

    Hi everyone,

    I thought I had solved my previous issue - posted here:

    recent hotwater pressure drop to shower pump - help!

    Up until a month ago, I have had good strong pressure in the shower with plenty of hot water and then one morning a major loss in pressure. Pump is fine (it's a 2.5bar Aqualisa, twin impeller).

    I now have to bleed the hot water feed everytime I want a decent shower. It will run fine, at almost the original pressure, with good hot water, perfectly fine. A couple of cycles of use, she's ok. Then, when you come to turn it on again, low pressure for about 5 minutes and then the pump stops and starts intermittently. If you dial up the cold water mix on the thermostatic tap, she will kick into life at reasonable pressure, but ice cold.

    I then bleed the HW feed into the pump and the problem is solved - everything back to near enough normal....until a few cycles of use again and back to the same thing....until I bleed it and so on...etc.

    It's a classic 113l CW tank in the loft feeding the HW cylinder downstairs situation. I have checked for gunk that might be blocking the cw tank outlet, but nothing I can see. I was quite shocked to see limescale crystals floating on the surfaceof the passive side of the tank...like bloomin ice floes in the arctic!

    The other weird thing, is that the 2nd bathroom which I installed a Mira power shower with a cold feed branching off the mains in the loft, is now also underpowered, my kids reported to me recently, said it had been like that for weeks but no one told me! In the past, that has worked very well, with the economy mode being used as anything else above was apparently just a tad too powerful. I checked our mains supply to the property and it's just over 3Bar. It's a simple copper pipe about 4m from the mains down to the Mira power shower and it is new copper pipe I installed 18 months ago. Un fathomable mystery!

    So - first off - I will be fitting one of those anti limescale BWT filters to the mains feeding the tank.

    I am also thinking about draining the CW tank and chucking some kilrock descaling fluid down the bottom...incase there's any limescale build up in the pipes leading out the bottom of the main feed.

    Does anyone have any other suggestions as to what else I might try?
     
  2. Riley

    Riley Plumber GSR

    Let’s have a few pics of your hot water cylinder/pump set up. Are you using a flange or is the hot teed off
     
  3. Big_Al

    Big_Al New Member

    Hi Riley,

    Thanks for your reply. Not too sure what you are asking - I am just an enthusiastic amateur...the howater feed goes directly to the pump?

    Thanks - see pics as requested. Hard to get an overall view of it but hopefully you can make out what's what :)

    20180914_084418.jpg

    20180914_085006.jpg

    20180914_085018.jpg
     
  4. Gasmk1

    Gasmk1 GSR

    i am a gas man not a plumber but think you will find not plumbed correctly draw off should have a surrey flange (or similar) and i suspect your tank may be too small
     
  5. Riley

    Riley Plumber GSR

    Yep agreed plumbed wrong. Should be on a Surrey flange as per the manufacturers instructions
     
  6. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    WTF , are they jubilee clips holding the blue hose on ?
     
    • Agree Agree x 1
  7. Big_Al

    Big_Al New Member

    I appreciate the comments from folks far more knowledgable than me, but everything you see here pictured, in terms of pipework....etc, has delivered plenty of hot and cold water to where it's been needed at good pressure, since I moved into this house for the last 5 years or so. Nothing structural has changed to what you see. The pressure drop...etc started out of the blue about a month ago.

    Deep descale and flush of the whole system? What sort of cost would I be looking at? Any other ideas?
     
    Last edited: Sep 14, 2018
  8. rpm

    rpm Trusted Plumber Top Contributor!!

    Do not put Kil-Rock through the pump.
     
  9. Big_Al

    Big_Al New Member

    Thanks - I won't :)
     
  10. Riley

    Riley Plumber GSR

    That’s as maybe but it’s working more by luck than by design but know that it’s wrong. It could be that your ball valve in the tank in the loft is partially blocked and isn’t replenishing the water quick enough allowing air into the pipework.
     
  11. rpm

    rpm Trusted Plumber Top Contributor!!

    Pipes going down then rising up then down into the pump was never a good idea.
    Yes it may have worked fine for 5yrs but it isn`t fine now is it. Don`t know a lot about auto bleed valves or where one might be installed in that lot but I`ll chuck it in the mix anyway for somebody else to comment on.
     
    • Disagree Disagree x 1
  12. Chewitt

    Chewitt New Member

    As above comments, you have been lucky the system has worked.
    I am not an installer but have sold shower pumps for over 30 years.
    I would always advise the following minimum requirements
    50 gallon 227 litre cold water storage tank.
    48x18" 1200 x 450mm cylinder 180 litres
    Surrey flange for cylinder.

    I believe that your pump and cylinder are drawing the water quicker than the ball valve can refill. Try watching in the loft when the pump is running.
     
  13. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    I would love to rip that lot out and do it properly
     
    • Like Like x 1
  14. rpm

    rpm Trusted Plumber Top Contributor!!

    I'm sure you mean carefully cut and remove it taking great care not to damage anything. :D
     
    • Funny Funny x 2
  15. Cailean

    Cailean Member

    That set up is a bloody mess. The fact that it's lasted this long should be recorded in the Guinness book of records.
     
    • Agree Agree x 1
    • Funny Funny x 1