Connector pipes

John Pilger

I have a question for all you seasoned pro's. In NFPA 211 (Standard for Chimneys, Fireplaces, Vents and Solid Fuel Burning Appliances) it states that the male end always goes toward the appliance. This is to keep creosote and condensation in the connector pipes. Every oil and gas-fired appliance I see the connector pipes have the male end toward the chimney. Almost all appliance manufacturers have their flue outlet with the male end toward the chimney, but NFPA 31 does not address this and the default is NFPA 211. My take is that the male end should go toward the chimney to reduce turbulence in the connector pipe and reduce soot leakage thru leaky joints when you get that burst of positive pressure on the appliance start up. Am I wrong here? Any help would be appreciated.

John Pilger

Phil_20

The application of the code you are talking about is in regard to SOLID fuel. Gas and atomized fuel oil are regulated by NFG code and the male end always goes with the flow.

Brad White

That is correct

The "Male-End Toward the Appliance" is for solid fuel and is intended to prevent the creosote from back-flowing out of the pipe and to ensure it flows back to the appliance for combustion if it can.

It does seem counter-intuitive at first though, doesn't it?

John Pilger

Connector pipes

Thank you for the responses. I have checked NFPA 54 the National Fuel Gas Code and I can't find anywhere where it gives the direction of the connector pipes. Maybe I am missing something, can you please give me the section and paragraph it is in so I can use that section to prove my point.