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Second guessing

Looked at a radiant slab install for a customer last week. The customer had radiant installed in another building using a different contractor. ( I spent two days redoing that so it was done properly) I had my wholesaler do a heat loss for the new building slab and it just seems off. Might be I have not done a floor in a long time.



40x40 building with a first floor that is 2x6 construction. The slab is basically the basement with the foundation being half above grade and half below. There are two 12x13 roll up doors and a steel entry door. The 8' foundation walls that are below grade are not insulated. 4' slab, 13'6" height to heated first floor ceiling.



Wholesaler came up with 12 loops of 1/2" tubing @ 200' loop lengths.



Designed for 115 water temp at 0 degree design temp.



Maybe I am just off but it seems like a lot of tubing?

Comments

  • ZmanZman Posts: 3,341
    Questions

    Are you saying you are heating a 1600 sq foot space with tubing at 9" centers or are there 2 floors?

    What kind of underslab insulation?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • AFOCTAFOCT Posts: 3
    Answers

    The building is basically a one floor house. I am just putting the tubing in the floor of the basement. Unfortunately he purchased enough "insulation to do this floor from the previous contractor. It is insultarp. ( Don't get me started on this stuff) I did talk him into 2" perimeter insulation.
  • ZmanZman Posts: 3,341
    Output

    Siggy's software puts your output at about 62K BTU or 39BTU/ft. at the 115 design temp.

    That seems a little high but considering the insutarp (I agree it is crap) and the under insulated walls I think I would run with it unless you do a heat loss calc that tells you different.

    Too much radiation is never a bad thing, particularly if you are running a condensing boiler.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SWEISWEI Posts: 7,356
    Not quite clear

    Are you planning to heat the basement and let the first floor (which sounds like it could be 4 feet above ground level) live with the leftovers?
  • AFOCTAFOCT Posts: 3
    .

    Yeah the second floor will be heated off a second zone. My heat loss came up with 63k. I think I just haven't done a radiant install in awhile so I must just be overthinking it. The boiler is gonna be condenser.



    Thanks for the input fellas!!!
  • RichRich Posts: 2,184
    12 @ 200

    Is 12" oc layout . 1,600 ft building , 2400 feet of tube .  Besides the lack of quality insulation . Sounds as if the average depth below grade is 4' , any chance the guy will excavate tat and install 2 - 4" of EPS or XPS up against that wall ? That would be a huge help . 
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
  • ZmanZman Posts: 3,341
    12"?

    Rich,

    Wouldn't 12" centers be about 1,600 feet of tubing? It would be a little more for the manifolds but pretty close to a tube every foot. Certainly not 2,400 feet of tube in the floor.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RichRich Posts: 2,184
    Z

     there are in fact 3 lineal feet of tubing in two square feet . @ 0" - 12" - 24" .  And due to the time of my post last night I reverted to my default 1 trip to the supply house calculation , I do apologise , after reading this now in my office after coffee and being wide awake I correct myself and say 12" center would require along the lines of  1,850 ft with leader lengths and 9" spacing would require about 2340 feet . You are correct .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
  • ZmanZman Posts: 3,341
    No worries...

    I was checking my own sanity more than anything.....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RichRich Posts: 2,184
    Default in my mind

    when I am out in a remote site I always order 3 lineal feet for every 2 square , 0" 12" 24" , 3 lineal feet for 2 sq . We save lots of trips this way and always have stuff in shop for those small jobs .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
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