Gledhill Stainless Lite Indirect

Discussion in 'Plumbing and Central Heating' started by socdesign, 9 Feb 2013.

  1. socdesign

    socdesign

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    Looking for some advice here:

    Plumber fitted a 210 litre stainless lite indirect cylinder to my system boiler. The house incoming pressure is just above 2 bar. The cylinder kit came with a combination valve and pressure vessel. The combination valve comes preset at 3 bar, although the house is less than this. The combination valve has a 22mm incoming cold water feed which is after the alkathene and double check / pressure reducing valve also set at 3 bar.

    So, to the issue: The expansion vessel appears to be popping violently a few times when the hot water is heating in the cylinder and randomly in the evening. It also pops initially when the hot water tap is run.

    Initially, when the tap was run, the vessel would also judder, but the plumber reduced the vessel pressure to just above that of the incoming and the judder stopped. The pop's still happen though.

    He has tried evacuating any air from the water side of the expansion vessel, and has also tried various expansion vessel pressures to no avail.

    Another recent thing to note is that a guy up the road also just had a Gledhill cylinder fitted (not same plumber) and his is popping in the same manner.

    I thought that this may be a water pressure issue with the estate, but my plumber said that he's installed other systems at lower pressures and has never had an issue like this. So, is there anything that can be done ? Could it be a fault with the vessel or cylinder ? May it just be that the Gledhill doesn't work under 3 bar (paperwork does not give lower limit - just says works at lower pressures than 3 bar!) ?

    Also, what actually causes the popping. I had read that it was a rapid deflection of the diaphragm in the vessel and I can believe that of when turning the tap on, but I would have thought that the expansion when water was heating would have been at a very slow rate.

    Any expert advice appreciated.
     
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  3. Is the expansion vessel connected to the pressure limiting valve
     
  4. mickyg

    mickyg

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    it sounds like there could be a big difference between your standing and dynamic pressure, there's not alot you can do about that
     
  5. socdesign

    socdesign

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    The expansion is fitted to the cold water inlet to the cylinder. This was moved from the expansion vessel port on the valve after a suggestion from another plumber who fits the Gledhill cylinders.

    If the pressure range is the issue, is my only recourse to have all this removed? Apart from the popping, all taps and showers are perfect.

    Still not clear on why the diaphram pops when the water is slowly expanding...
     
  6. socdesign

    socdesign

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    The dynamic pressure goes down to about 1.2 bar. Standing/static at 2.2. When hot water expands it reaches 3.2
     
  7. mickyg

    mickyg

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    you can stop the farting noise by lowering the EV pressure as your plumber has done, but the other noise sounds like the tank itself expanding and contracting. The gledhill lite is light because the metal is thinner than other UV cylinders, so its probably got more flexibility when expanding/contracting, hence your noise.
     
  8. socdesign

    socdesign

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    Ouch! Looks like it could be £500 down the drain then (no pun intended). Will have to have this ripped out and a decent make fitted, as the popping is really quite loud and certainly not something that could be lived with long term.

    When it was suggested that a wide dynamic to standing pressure differential could be the cause, I thought that getting a bigger vessel and lowering the diaphragm pressure may have provided a solution. The bigger vessel then coping with the dynamic to static range plus the hot water expansion range. Would really need an experts opinion on this.
     
  9. Have you contacted gledhill?
    I have fitted a lot of their cylinders and never had any problems.
     
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  11. Fluffster

    Fluffster

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    Just as a matter of interest which way is the vessell positioned, air valve on top or bottom. Is the pipework to the vessell copper or a braided hose?
    I was called to deal with a similar issue years ago which was resolved by postioning the vessell with the valve on the bottom and piping in copper. The flexible hose was too long and kinked in a coil when at cold pressure, when volume increased hot it would whip open like a garden hose and send a good belt of sudden pressure to the EV.

    Pete
     
  12. mickyg

    mickyg

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    yeh but i bet you wouldnt fit one if someone had 1.2 bar dynamic pressure ;)
     
  13. socdesign

    socdesign

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    The expansion is fitted vertical with the inlet pipe to the bottom. It's piped in 22mm copper.

    The installation manual for the cylinder states that the combination valve reduces to 3 bar, but does not give any indication of any lower operating limit for the cylinder. Just states that it will operate at lower pressures.

    Time to dial that premium rate helpline.
     
  14. Your right I probably wouldn't.

    I'm still not sure what's causing the popping though.
    Are you suggesting the cylinder in contracting?
     
  15. mickyg

    mickyg

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    yes, my own ariston one does it a little bit as i have a 1.5bar difference between working/standing, but its not very noticable, it makes sense that if the metal is thinner the flexibility will be greater.
     
  16. socdesign

    socdesign

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    Just a quick update on this:

    The bang/loud pop is actually coming from the Cylinder and not the expansion. Different EV pressures have been tried, but the pops still happen randomly. It appears that the cylinder doesn't like the range of pressures (all under the upper limits). As someone mentioned previously, this may be down to the thinner metalwork, or perhaps even a fault??? It's a pretty loud noise though - like someone slapping their hand down hard on a desk.

    Awaiting Gledhill support. :(
     
  17. Agile

    Agile

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    Thats considered the correct way.

    I would always fit with 15 mm ( or smaller ) connection tube. It only needs to handle the expansion flow and can cause noises otherwise.

    Please let us know what the makers suggest. Perhaps they should supply one with thicker walls?

    Without any warning of problems like these a replacement should be at their expense ( together with the fitting cost! ).

    Tony
     
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