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eddah357 Member Posts: 4
Anyone know how I can figure out how many BTU's 1/2 Fostapex can support. The home I moved to has 1/2 Fostapex feeding 3 rooms with standard hydronic baseboard, this zone recently froze with the extreme temperatures we had in Massachusetts.

I would like to verify total piping length and baseboard calculation to verify 1/2 can support the installed baseboard.


  • hot_rod
    hot_rod Member Posts: 22,472
    A bit over 2 gpm will be the comfort range for 1/2" pex

    Here is a 100' loop, 12 elbows, 2.25 gpm at 180F.  The flow velocity of 4 fps is acceptable.

    A fin tube system designs around a 20° delta so 20,225 btu/ hr is a reasonable number

    If you know the exact length of the loop, number of fittings, or if you have glycol in the loop, the calculator is at the PPI website.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream