on my old boiler it was used because it had a HUGE masonry chimney and i suspect that it took so long to heat up that the draft was unacceptable.

i dont know if it was just too big from the start of if the original boiler may have been different in design and it worked fine for it.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.