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View Full Version : Max bends of a furnace flue



Rich Sumen
06-09-2011, 01:57 PM
Does anyone know code or rules or the amount of bends allowed on a flue?
A HWT and a 92,000 BTU furnace flue connect together properly, (single wall pipe) but then have 3, 90 degree bents, each about 3" apart before they
turn up into a "B" vent pipe. (a total of 4 bends including the turn up, from the furnace and up, at the end of the run, into the B pipe) All piping slopes up properly, about an inch per foot.

Thanks / Richard

Matt Fellman
06-09-2011, 10:10 PM
I remember reading about a max # of bends rule when I was training years ago but have since learned that it all pretty much comes down to manufacturer specs. There are tables and rules in the extensive fuel/gas code but in most cases the manf. instructions are your best bet.

What you describe sounds odd..... a picture would help a bunch.

Tom Thompson
06-09-2011, 10:42 PM
CA. code
Only 1/3rd of the total vertical vent rise can be horizontal, any angel greater than 45 degrees is considered horizontal. No more that one offset not greater than 60 degrees is allowed. 75% of the total vent must be vertical. The vent connector (between appliance and chimney) can be installed at 1/4" per foot rise, it's still figured into the 1/3 rd horizontal.