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Loops and Pumps for Garage Radiant System

I have an insulated 30' X 36' garage with 10' ceilings. I installed 4 loops (280' each)of 1/2" pex in the floor with 2" poly under the slab. I have decided to go with a Navien NHB-55 boiler running natural gas. I have picked up a Grundfros 15-58 and was planning on just setting up one loop with the pump on the return side of the boiler. I am beginning to second guess whether I should be plumbing a primary and secondary loop with a second pump before the manifold. Am I running into a problem with not setting up a primary and secondary and/or will a single 15-58 be adequate? For reference the 15-58 is specified by Navien and I am in South Dakota where wind chill be be -40 F. Any help would be greatly appreciated.

Comments

  • hot_rod
    hot_rod Member Posts: 18,190
    Looks like Navian is indicating primary secondary piping, either use their kit or build you own set of close spaced tees.

    Use they pump the suggest for the boiler, another 15-58 on the radiant loop manifold, feeding all your tubing.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Dakota_Winter
  • Dakota_Winter
    Dakota_Winter Member Posts: 3
    That is where I was leaning. Just out of curiousity, what would a primary/secondary loop do for this setup or why does Navien call for it?
  • hot_rod
    hot_rod Member Posts: 18,190
    P/S piping assures that that small heat exchanger, flow sensitive boiler always gets adequate flow thru it, regardless of what zones or loops are running. It's really to assure the boiler is protected and can lead a long, happy, trouble free life.

    It's also the first question tech support will ask the you call them with boiler issues :) How'd you pipe it?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Dakota_Winter
  • Dakota_Winter
    Dakota_Winter Member Posts: 3
    I appreciate the help. Thanks a bunch