65 ft of fintube?

powerhead

I once heard of a rule of thumb that you can't run more than 65 ft of 3/4 fintube per zone or else you will "run out" of heat. I think this had something to do with maximum gpm through a 3/4 pipe. Does anyone know how this rule works? Does the 65 ft include pipe and fin or just fin alone?

Mark Eatherton1

Yup...

that there would be the finned tube limitation for 3/4" pipe at a 20 degree delta t...

65 feet times 550 btu/foot = 35,750 btuH. That, divided by 10,000 (btuh 1 gpm will deliver at a 20 degree delta T) = 3.57 GPM which is pert near the maximum recommended gpm through a 3/4" pipe based on silent operation.

Powerhead, thats a new name. Welcome to the Wall. Hang out and learn something, will ya:-)

ME

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powerhead

Thanks Mark,

I think I will.