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5/8 wirsbo tubing

chris_40
chris_40 Member Posts: 12
in THE MAIN WALL
does anybody know how many linear feet of basebord element you can run through wirsbo 5/8 tubing

Comments

  • Brad White_97
    Brad White_97 Member Posts: 15
    What is the rating of the fin-tube?

    I do not have Wirsbo-specific charts but I would consider 1.5 to 2.0 GPM to be a reasonable flow rate. Velocity in the 1.4 to 1.8 FPS range and PD's around 3 feet per 100 feet conservatively.

    15,000 to 20,000 BTUH at a 20 degree drop would get you 30 to 40 LF of baseboard at 500 BTUH per, but please do not do that. Too long a run for even heating IMHO. Also you may want to consider Pex-Al-Pex if you are running higher temperatures (which will get you to the 500 BTUH/LF range.

    In short, I would consider any length you would normally serve with any piping (say to 20 feet) to be reasonable. Naturally you can serve longer runs but have to compensate for decaying water temperature along the way.
  • chris_40
    chris_40 Member Posts: 12


    the homeowner has 5/8 tubing running 56 linear feet of bb and added a 30 galon storage tank and wants to know why his bill is so much higher.the total run of pex is probably 180 ft.i was considering a split loop.any advice
  • Brad White_97
    Brad White_97 Member Posts: 15
    You mean the energy bill, Chris?

    That would make sense. Not sure if the storage tank is a buffer tank or is it DHW?

    I can see the radiation petering out quickly especially if on one loop. You are on the right track, I would also suggest as you said, splitting the BBR into more manageable segments.

    The energy cost would be higher because the thermostat would be singing as Mick Jagger would say, "I can't get no... satisfaction... So it runs and runs to less avail. Add more pump and you do not do much more good even with double flow. If you are running say, 3.0 GPM, your pressure drop per 100 feet would be in the 6.25 range. Over 180 LF this is almost 11.5 feet (5 PSIG).

    If the BBR is worth conservatively 400 BTUH per LF (versus 500-500 it might be, taking the low end of the scale here), that 22,400 BTUH potential could not be sustained at the end runs. You may be petering out about half-way with the last element suffering. I would hazard a guess that the thermostat is in a room toward the end?

    If the radiation has been derated for lower temperature water (increased to compensate) all the better, but still...

    Split the loop, yes.
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