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Pump speed/Automatic bypass valve setting.

Discussion in 'Plumbing and Central Heating' started by Mottie, 23 Apr 2018.

  1. Mottie

    Mottie

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    I have the following setup. Is there a simple(ish) process for setting up the pump speed and bypass valve settings? Would you first set the pump speed and then adjust the valve to suit the pump speed or does it not matter? Is a lower speed better than a higher speed? Why are there different speeds - why not just one? Should the bypass valve need readjusting if you changed the pump speed - presumably there’ll be more pressure to open the valve at higher pump speeds so should the valve be tightened a little? Or loosened off on a low speed?

    Another question, is it common for the valve to make a noise when it opens? The reason I ask is that after I have my shower go to bed at night, about 15 minutes later I hear a funny one-off farty/groany squeak. I just got the exact same noise when I loosened off the valve so I assume the noise that I’m hearing is the valve opening when the hot water has reached temperature, the zone valve closes and the pump overruns. Is that normal or does the bypass valve need changing - it’s only about 15 months old. Or is just good old trial and error. :D Thanks.

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    Last edited: 23 Apr 2018
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  3. D_Hailsham

    D_Hailsham

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    First, you set the speed, then you set the bypass. The speed required depends on: 1. the size of the system (no of rads and layout); 2. the required temperature drop across the system.

    So the same pump can be used in different sized systems.

    The valve will need resetting if the pump speed is changed.

    Your pump has six settings: three fixed speed (permanent lights) and three variable speed (flashing lights). An auto bypass valve does not work correctly when a variable speed is selected.
     
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  4. Mottie

    Mottie

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    Thanks. Right. I have 10 rads and a (knackered and soon to be replaced 60;000 btu) boiler. Speed 1 seems too slow for the heating. Speed 3 is probably too fast for just hot water so I’m going for 2. It’s been on that speed for ages so I’d best leave it at that and adjust the bypass valve for that speed. I was unaware about the variable speeds on my pump though - how do I get them? My pump just cycles between 1,2 or 3 when pressing the button and I only get solid lights.
     
    Last edited: 24 Apr 2018
  5. heatservice

    heatservice

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    Your pump is a standard UPS2 15-50/60 3 speed pump it the Alpha2 model which is variable speed.
     
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  6. D_Hailsham

    D_Hailsham

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    Are you sure about that? I have the same model pump and it has three fixed speeds and three variable (proportional pressure) speeds
     
  7. heatservice

    heatservice

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    As far as Im aware the UPS model only has 3 speeds I think on the older models you could remove a screw from the inlet port which gave you a slightly better flow on each of the speeds, dont know if the newer models have that also but their not variable.
     
  8. Madrab

    Madrab

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  9. heatservice

    heatservice

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  11. D_Hailsham

    D_Hailsham

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  12. heatservice

    heatservice

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  13. Madrab

    Madrab

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    OP, can you please press and hold the speed button on the pump for around 5 odd sec and see if the green speed light then goes from solid to flashing?
     
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  14. Mottie

    Mottie

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    Yep. It flashes. And stops pumping. Thought I'd buggered it up - had to press and muck about with the buttons to get it working again!

    When I have a new boiler, will that work with it or is it still best to pick a speed and stay with it?
     
  15. Madrab

    Madrab

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    Sorry should have said just do it again and hold and it should reset back to normal speed settings, when it flashes that's it going into it's variable speed setting so it is the dual speed pump.

    Yes, that pump should be fine. If you are gong to play around with it though I'd suggest you get Foss's own manual for it so you know what to do with it and how to set it up. The correct speed setting requires you to know certain technical values for your CH system, as @D_Hailsham alluded to earlier, so I'd suggest it's time to get a better understanding of how the system works and how it needs to be setup before playing around any more (y)

    Do some reading up as it can get too long winded to explain on a forum post
     
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  16. Mottie

    Mottie

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    Ok thanks. I’ll leave it as it is for now and look into it further after I’ve had the boiler replaced.
     
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