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Hydronic cool heating issue

danitheplumber
danitheplumber Member Posts: 85
in THE MAIN WALL
Have a customer with two coil units. One supply is 180f returns 140f and the other gets 160f and return is 100f. The coils get heater by boiler that supplies 4 other units and they're not having any issues and all there sensor indicate normal supply and return temperature. The system was bleed and there's full force of water coming out and water comes out hot. What could cause only one coil to only get 160 and a return of 100 and not a single other fan coil has this issue?
Here are some pictures.
Any suggestions or information would be greatly appreciated. 

Thank you and happy holidays.

Comments

  • bburd
    bburd Member Posts: 1,041
    Sounds like restricted water flow at the cooler unit, or unbalanced flow. 

    How old is the system? Your delta Ts are wide for an older system.
    —
    Bburd
    danitheplumber
  • danitheplumber
    danitheplumber Member Posts: 85
    Customer said he had contractor put it in 3 years ago at the same time the building management put boiler in for entire property. So everything is 3 years and no issue except this week with this one fan coil.
  • bburd
    bburd Member Posts: 1,041
    Check water flow rates through coils if possible. Compare to specs.
    —
    Bburd
  • HVACNUT
    HVACNUT Member Posts: 6,334
    How far away is the 160° coil? Insulated?
    Are all zone SWT's equal leaving the manifold ?
  • danitheplumber
    danitheplumber Member Posts: 85
    He has two units 12 feet apart one works great second one is having issues. They both work fine and now one can only gets 160f and 100f on return even though sensor on boiler indicated 179 supply and 173 on return. The room it serves doesn't get over 65-68f and runs all day. they need it at 73 to be comfortable.
  • Bill_17
    Bill_17 Member Posts: 68
    Are you able to measure the flow rates to each fan coil and provide a full system diagram? It looks like there is at least one flow meter, if so, perhaps you can open only one zone at a time and measure flow rate and temperatures across each fan coil and post the results. If the temperature of the offending fan coil goes up to what's expected, then try opening one more zone randomly, document the results, then try another second zone, do this again and try some different combinations as we are looking for clues. Report back with your findings.

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