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  1. #1

    help with in floor radiant heat

    Ill start from the beginning. I went to the customers house there was a leak on the return manifold. I tried to get replacement parts but was unable to... so i replaced the supply and return manifolds. Since doing so the floors dont get warm enough and the kick board heaters(2nd stage) are over heating. I cant seem to get any heat to the floors.

    There are 3 zones two of which have 2nd stage kickboard heaters. The system isnt piped primary secondary like i would of liked, the supply and return run out from the boiler first tying into the first kickboard heater then the infloor radiant heat manifolds then to the last kickboard heater to complete the loop.

    I have the infloor looped balanced at .75 gallon a minute according to the gauges on the supply manifold, the radiant mixing valve set to 120 degrees. The tubing is 1/2 inch pex

    Name:  radiant.png
Views: 326
Size:  12.6 KB

    bad picture but gives you an idea of how its piped. What should the flow rate through the pex to get good heat transfer? Any info would be great thanks

  2. #2
    Join Date
    Dec 2003
    Location
    Northern VA
    Posts
    622
    I know that this is obvious..... Air??
    "Iron sharpeneth iron..."

  3. #3
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,011
    Hydronics 101: flow & temp drop will tell you the btu's/hr you're delivering to the floor.
    You said you balanced the flow to .75gpm with 120 input. Q = 500 x .75 x 20. 20 being the highest delta T a residential temp drop should be (IMO) Q = 7500 btu's/hr.
    Now, if the .75 gpm was across the entire manifold, not much heat going out to the zone/hr when you figure it's across X amount of loops. If that was the flow on each loop that should be showing some warming in that zone.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  4. #4
    Join Date
    Sep 2012
    Location
    Ottawa, Canada
    Posts
    28
    You will need to remove the air that YOU put in the system

  5. #5
    It΄s not just the air You will have to remove. To do that You will have to control that You have the RIGHT static pressure (P0) in the vessel and the right Pa for the system.


    Br // Michael
    Last edited by beenthere; 12-19-2012 at 05:48 AM. Reason: Removed link to his company

  6. #6
    Sorry!
    Wrong link.
    Use this: <Removed link to your company>
    Then download the animation that You find under "Documentation" - Mowies/training. // Michael
    Last edited by beenthere; 12-19-2012 at 05:50 AM. Reason: Removed link to his company

  7. #7
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    If you haven't you need to purge it out. Loop by loop force the air out.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,033
    Michael, you must be a Pro member to have a link to your company, and then it must be in your sig, not in the post body itself.

    Please get your post count up to 15 and apply for pro membership, thank you.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Aug 2011
    Posts
    37
    stop and purge

  10. #10
    Join Date
    Sep 2011
    Posts
    50
    If the problem is in the system (aside from air) I wouldn't be able to tell you for sure where to start because the drawing is pretty poor.
    I can only assume what is where and by what I am assuming..... The loop isn't even built correctly. I'll assume I am mistaken but sorry, I cant deduce anything from this and this is what I do.

    Just because it was working before you got there doesn't mean it was right before you got there.

  11. #11
    Join Date
    Sep 2011
    Posts
    50
    Name:  121.png
Views: 100
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    Here is what it should look like if you want everything to work. Is this how it is put together?.

    Cant find the option to delete a post so guess I am working on my post count now

  12. #12
    Join Date
    Sep 2011
    Posts
    50
    Name:  121.png
Views: 100
Size:  25.2 KB

    Here is what it should look like if you want everything to work. Is this how it is put together?.
    (opps!) in my haste to draw this out, I brought the kick heaters return in front of the mixing valve. That should be after the mixing valve toward the boiler. Adding a flow check between the kick heater and radiant return isn't a bad practice either.

  13. #13
    Join Date
    Sep 2011
    Posts
    50
    Name:  122.png
Views: 107
Size:  25.5 KB

    Like this

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