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Seeking Guidance for DIY Radiant-in-Slab

hi all,

i have a semi-detached brick 2-family home in brooklyn. 20' x 65'. tenants are on the top floor and we occupy the first 2 floors. our ground floor is about 3 feet in ground on 3 sides and at grade in the rear. we are renovating and intend to put 2 full bathrooms and 3 bedrooms there, in addition to the laundry and utility room. we recently install a navian ncb240 which currently serves our dhw and baseboard radiators for both floors (tenants have separate boiler).

we are preparing to remove the current rat slab and repour a new slab on the ground floor. we will install a french drain, vapor barriers on both the walls AND floor. additionally, we will lay 2' polyiso insulation beneath the new slab. finally, i want to lay tubing before the pour.

throughout my research, i've taken note of the following considerations, of which i am still trying to firm-up:
1) 1/2" pex w/ oxygen barrier,
2) 12" center (though some say closer, depending on heat loss analysis),
3) keep loops same length (prob around 220' for me), what is margin of difference? 5'?
4) mixing stations (later, i will staple up tubing to heat upper floor, so higher temp needed),
5) remote manifold toward center is recommended because boiler is at end of floor.
6) sensors?
7) glycol?
8) how far do i lay tubing from interior walls, which are not up yet, and plumbing for 2 bathrooms?
9) what am i missing?

this site was recommended as a place to get contentious and informed advice. ALL IS APPRECIATED.


  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    edited September 2015
    Might want to contact the Radiant Panel Association for a contractor referral? Design work needs to be done to nail down tube spacing, loop lengths, water temps, flow rates, heat loss, etc. Where are ya?
  • Rich_49
    Rich_49 Member Posts: 2,738
    He's in Brooklyn Bob .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    Bob Bona_4