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Flow problems when opening mixing valve

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LDlong
LDlong Member Posts: 2
in Radiant Heating
Attaching pics of setup. We've got an outdoor wood boiler that runs through a fan and heat exchanger for shop floor heat. We then put in a tankless water heater for backup. We're getting almost no flow if we try to send it through our heater and mixing valve. If we close (let the cold run through) the mixing valve we get 3 gpm total flow. Any help would be appreciated

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  • MNSteve
    MNSteve Member Posts: 10
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    tankless heater head loss

    Your photos didn't show up so this is just an educated guess. However I would guess that the tankless heater you are using is a high head-loss model, and your pump is unable to circulate through the WH's heat exchanger.
  • LDlong
    LDlong Member Posts: 2
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    took mixing valve out

    we went ahead and removed the mixing valve. Trying to get air out now. In doing more reading on the board, we're thinking we'd better do a primary/secondary loop. I've tried to get pics and can't seem to get them to show. Any extra info on where the expansion tank and pressure relief valve and mixing valve should be placed would be very much appreciated.

    /Users/1/Pictures/iPhoto Library/Originals/2011/Dec 27, 2011/DSCN1414_2.JPG
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