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How to set an automatic bypass valve

Discussion in 'Plumbing and Central Heating' started by lavinpj1, 7 Oct 2015.

  1. lavinpj1

    lavinpj1

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    I have a Worcester 40CDi Classic Regular boiler. The valve ranges from 0.1-0.5 bar. From various things I've seen, you need the pump head and boiler minimum flow rate to calculate this.

    The pump is adjustable between 0m and 6m head, but it's always been set on 5m. Not sure if this is the correct setting... any advice?

    I spoke to Worcester who said the minimum flow rate of the boiler was 1.5l/min.

    What should the bypass be set to?
     
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  3. Agile

    Agile

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    You seem to be confusing CH and DHW.

    The auto bypass valve is only needed if you have TRVs.

    Makes me wonder why you suddenly want to fit one.

    Any combi needs the pump set on maximum, I am assuming your's is a combi !

    Typically set the auto bypass to 0.2 bar. There are many web sites suggesting how to set them more closely to suit any particular system where the objective is to set them to just start flowing when 2/3 of the TRVs are off.

    Tony
     
  4. lavinpj1

    lavinpj1

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    I have 3 zone valves which are all closed when the heating and hot water turn off.

    The boiler does pump overrun when there is no more call for heat. This process requires the bypass such that there is still water moving around.

    It's not a combi. The pump is external to the boiler and is adjustable from 0-6m head.

    I'll try this value, thanks.
     
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