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Radiant ceiling help

IZZY
IZZY Member Posts: 50
I built a bedroom addition over my attached garage.  I want to do a radiant ceiling. The joists are 2X8 but I'm putting in R-30, so it should extend above the tops of the joists and touch to make a nice insulation blanket.  I figured I would run it by putting 3/4" plywood strips to the underside of the ceiling joists, running across the joists.  I am planning on using 1/2" pex, 8" on center (both chosen because they seem pretty standard), so to leave a 3/4" gap between the plywood strips, each strip will be 7 1/4" wide.  Heat transfer plates stapled to the plywood, with the omega sitting in the 3/4" gap between the plywood strips.  Then 1/2" sheetrock screwed through the plywood and into the joists, being careful to avoid the tubing.  I've attached a sketch.

Will this work?  Any help/guidance greatly appreciated.

Izzy

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Should work GREAT!

    I have a radiant ceiling in my weekend mountain home, and it is every bit as comfortable as a radiant floor system in my week day home.



    Enjoy!



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • IZZY
    IZZY Member Posts: 50
    Thanks so much

    Is there any concern of the lines freezing since the attic is above?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Theoretically... NO

    "cause when it gets cold outside, the heating system will be working hard :-)



    If in doubt, you can induce anti freeze, but it is messy.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Gordy
    Gordy Member Posts: 9,514
    Nice design and your Gonna Love it!!

     Mine is going on 60 years old never had a freeze up. Its been down to 2.5 times the normal design temp for the area in its history normally -10 gotten down to -30. The original attic insulation was only 5"  of vermiculite.





    Gordy
  • IZZY
    IZZY Member Posts: 50
    Thank you

    that actually makes perfect sense, not sure why I didn't realize that. Thank you again.
  • IZZY
    IZZY Member Posts: 50
    Thank you

    I have been REALLY excited to do this and everything about it makes all the sense in the world, but all of the guys I know who have installed radiant are stuck in their little worlds of "all they have ever done or seen done is radiant in the floor".  So I've been getting a lot of "I don't know if that's such a good idea" or "that will never work" type of responses from my "peers".  This has actually made me want to do it even more to kind of stick it in their faces.  So anyway, thank you and Mark Eatherton for the encouragement.
  • Gordy
    Gordy Member Posts: 9,514
    edited October 2011
    Izzy

     Think about it like this. With radiant ceilings you dont have to worry about floor coverings, and furniture blocking outputs of the panel. You feel the effects of radiant ceilings when you are laying on the couch, bed or sitting in the recliner.



     I can verify temps from floor to ceiling are pretty even, with in 2*.



    Former non believer Gordy 
  • Sal Santamaura
    Sal Santamaura Member Posts: 324
    edited October 2011
    Turning the world upside down

    Mark, have you (or anyone you know) ever put Warmboard on a ceiling?  I know the substrate is thick (even the "R" version), but its even radiation characteristic might be just as useful up there as it is under a floor.
  • Gordy
    Gordy Member Posts: 9,514
    Roth USA

    Roth panel would be my choice.
  • NYplumber
    NYplumber Member Posts: 503
    edited October 2011
    Pros

    The pros out weigh the cons. You can run hotter water thus pulling more btu per square foot without adverse effects of being uncomfortable to step on.....because no one touches the ceiling.



    Did you do a heat loss calc to figure out your water temp?

    Also, I recomend you run it constant circulation on odr to minimize expansion/contraction noises.
    :NYplumber:
  • Gordy
    Gordy Member Posts: 9,514
    Limits

    Yes but there are limits to panel surface temps of 120*. Which is very hot. I usually see max panel temps of 87* on a design day. Water supply temps of 115* not much more than a radiant floor. Thats 50's construction, and panel design.



    All though my Chase copper, and Brass literature from the era bosts mean supply water temps up to 150*. 



    Yes NY plumber is right heatloss tells all in the design of the system... a must.



    Gordy
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