Thread: Maximum elbows allowed

I just had a Amana high efficiency gas furnace put in. When they got done I noticed that there are 7 elbows in the exhust and 5 in the combustion draw pipe.Wondering what the max is. Also is it okay to leave the combustion air pipe off and pull straight from basement? My parents is like that. Is plenty big of a basement but not sure on the rule there. Thanks!

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The first thing I would do is look at the installation manual, which you should have, or if you don't, it's no doubt available online.

Originally Posted by Eric Smith

Also is it okay to leave the combustion air pipe off and pull straight from basement?

Allowed by some manufacturers, not allowed or not recommended by others. Also, some manufacturers require an elbow or other protection at the intake at the furnace to prevent blockage.

Bottom line: check the manufacturer's installation instructions for the specific model of furnace or boiler.

Refer to g2427.4 for venting, cat 4 appliances as specified or furnished by the manufacturer.

The install manual lists how many 90's allowed based on pipe size and pipe run length. You have to look at the manual for that unit. 7 seems a bit much.