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Bleeding multi port zone

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Dave_94
Dave_94 Member Posts: 17
Have a boiler that was shut down due to indirect rotting and spraying water on zone control. After getting boiler up and running again there is only one baseboard loop and 3 radiant loops with mixing valves and proper shut off valves and purges. Two of the radiant zones each go to a 4 loop manifold with 3/8 pex runs same for returns and all have shutoff valves for each loop. Of course the radiant is air bound and my attempts at purging have failed. There is also a valve on return to shut off return water going thru mixing valve into the feed. Where can I find the proper bleeding procedure? I seem to have issues getting flow thru the individual manifold lines ( no return water ) even when bumping pressure up with feed valve. I tried with return to mix valve open and closed. The mixing valves are below the pumps on a pump away system. No purge valve for bleeding backward thru return. No shut offs on feeds to pump. Thanks for any advice in advance.

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  • hot_rod
    hot_rod Member Posts: 22,254
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    It depends on how it is piped.
    Some manifolds has iso valves and purge cocks right on them.
    If not a purge right at the mix valve return should do it.

    One or two zones at a time with a 1/2" fill valve is doable.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Dave_94
    Dave_94 Member Posts: 17
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    Thanks hot rod, that is what I was doing with return to mixing valve closed but was second or first guessing lol. Was unsure if feeding thru pump with mixing valve below was possible with return to mix closed. I will be more patient today and will let you know.
  • Dave_94
    Dave_94 Member Posts: 17
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    Ok one of the mixing valves was shot but with a cold boiler I got it purged. 3/8 th lines are a real pain.
  • hot_rod
    hot_rod Member Posts: 22,254
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    Take the pressure up to 25-27 psi for a faster purge
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream