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  • FIRST POST
    • purpleparrotuk
    • By purpleparrotuk 13th Jan 19, 10:02 AM
    • 257Posts
    • 38Thanks
    purpleparrotuk
    Automatic Bypass Valve question
    • #1
    • 13th Jan 19, 10:02 AM
    Automatic Bypass Valve question 13th Jan 19 at 10:02 AM
    I had an automatic bypass valve fitted to my unvented system yesterday and it was left at 0.4. Goes from 0.1-0.5. Anyhow I thought I would set it today according to the instructions. So I closed it off completely to th 0.5 mark and then turned all the trvs on. I then began turning it until the pipe started to get warm. Problem is the abv is in the airing cupboard and it is fitted to the pipes marked flow and return. The flow pipe is hot but the return pipe remains stone cold. Even after leaving the heating on for 10 minutes. So turning the valve makes no difference. Am I doing something wrong? Why is the return pipe stone cold?
    I just tried turning the heating off and the pipe from the ABV got red hot even though the ABV is turned off
    Last edited by purpleparrotuk; 13-01-2019 at 10:04 AM.
Page 1
    • fezster
    • By fezster 13th Jan 19, 10:22 AM
    • 297 Posts
    • 180 Thanks
    fezster
    • #2
    • 13th Jan 19, 10:22 AM
    • #2
    • 13th Jan 19, 10:22 AM
    An ABV is never "off" as such. Even at 0.5, it just has a much higher resistance. When the heating turns off, the motorised valve shuts, but you more than likely have pump overrun on your boiler, so the pump continues to operate for a period of time.

    As the water has nowhere else to go, it passes through the ABV.

    An ABV is usually setup to maintain minimum flow rates through your boiler. Have a look at the honeywell instructions to set it correctly:

    https://www.plumbworld.co.uk/documents/1-honeywell-du145-automatic-bypass-valve-installation-guide.pdf
    • southcoastrgi
    • By southcoastrgi 13th Jan 19, 5:06 PM
    • 5,492 Posts
    • 3,160 Thanks
    southcoastrgi
    • #3
    • 13th Jan 19, 5:06 PM
    • #3
    • 13th Jan 19, 5:06 PM
    If the guy fitted it yesterday he should have set it up so why are you mucking about with it ?
    I'm only here while I wait for Corrie to start.

    You get no BS from me & if I think you are wrong I WILL tell you.
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