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New Construction, Need Hydronic Piping Advice.

OldDude Member Posts: 1
edited February 2021 in Radiant Heating
Need to build Hydronic In Floor Control Panel for New Building [Shop & Apt].
Would like to know if this system will work, need advice or suggestions.
Complete piping diagram & parts code here:


  • hot_rod
    hot_rod Member Posts: 16,287
    A common P/S piping, looks fine. Is that Rinnai a water heater or boiler? If it is a condensing model, why the thermostatic mix valves/ seems you could just fire the boiler to the required SWT?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • OldDude
    OldDude Member Posts: 1
    The Rinnai is a Tankless Water Heater only, Non condensing, LP Gas 150000 BTU.
  • geno907
    geno907 Member Posts: 10
    is rinnai q series a pump into instead of a pump away boiler?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,190
    Most of the boilers are pump on the return. The expansion tank should be on the system loop, making that the primary loop. (according to Dan H. the primary loop is the one with the expansion tank). The boiler loop is now the secondary loop and the boiler pump should ADD pressure to the boiler heat exchanger to increase the pressure in the boiler. higher pressure in the heat exchanger will allow higher temperature before boiling the water. If you put the pump on the boiler outlet the pressure in the heat exchanger will drop, lowering the boiling point.

    I find that the manufacturer's instructions are usually pretty good as to where to put the pump(s) on these systems. Most of them have tested all the options and have put the parts in the best place for the best outcome.

    Yours, truly,
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org