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Secondary Loop Sizing.

jjheat
jjheat Member Posts: 35
in THE MAIN WALL
I have 2 Alpine 399,000 btu boilers that are twinning in to a common secondary looop that needs to deliver 80 GPM. Is 2" large enough???

Comments

  • kcopp
    kcopp Member Posts: 4,462
    looking at Dan's

    Golden Book of HH...2.1/2" would be better. 2" will only get you 50/45 gpm safely.
  • Henry
    Henry Member Posts: 998
    Design range

    Using the B&G "System Sizer Calculator" a 2 1/2 inch pipe is at the limit for "normally used design range" for 80 GPM. It has a friction rating of 4.5 Ft per 100 Ft of pipe, plus you must account for fittings and valves. This will affect your pump sizing.
  • Jason_13
    Jason_13 Member Posts: 304
    Alpine manual

    The Alpine manual calls for a 2-1/2" common pipe where both boilers tie into the manifolds. The boiler piping (secondary pipe) is 2" per the manual even though the boiler tapping's are 1-1/2".
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited September 2012
    If Each Boiler

    Can only provide 37gpm output on a 20 delta, how do you expect to get 80gpm? Just curious. On a 20 degree delta 3" pipe will carry 77gpm or 770,000 btu/hr. Increase the boiler delta to 25, select the proper pumps per the manual and you can pipe the primary or boiler side in 2".

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