Wood stove and water heater vented together

[inspectorreuben]

Why can't a wood stove and a natural gas water heater share the same vent?

[Jerry Simon]

Why can't a wood stove and a natural gas water heater share the same vent?

To get to the other side.

[gtblum]

To get to the other side.

Cold beer right out my nose!

[rkenney]

G2427.6.10 (503.6.12) Marking. In those localities where solid and liquid fuels are used extensively, gas vents shall be permanently identified by a label attached to the wall or ceiling at a point where the vent connector enters the gas vent. The determination of where such localities exist shall be made by the code official. The label shall read:

“This gas vent is for appliances that burn gas. Do not connect to solid or liquid fuel-burning appliances or incinerators.â€

[Bill Kibbel]

Why can't a wood stove and a natural gas water heater share the same vent?

NFPPA 211, NFPA 54 & The solid-fuel burning appliance listing.

[inspectorreuben]

Jerry - yeah, I know

Bob - I think you're on to what I'm after, which is the reasoning behind the code.

If someone else has a great explanation of why, I'd be interested to hear. I hate telling my client "you can't do this because it's code." Instead, I said it wasn't safe... but I really don't know why, and come to think of it, I guess I'm really not sure it isn't safe.

[Marc]

How's this: Flue gas temperatures are a factor in flue design since those temperatures influence the developed draft. What works for wood burning won't work for natural gas.

Marc

[John Kogel]

You don't want CO from a water heater leaking out of your woodstove, which can happen when the stove is cold.

And you don't want wood smoke and creosote belching out of your water heater vent pipe, maybe causing backdrafting as well.

[Jim Katen]

. . . and because wood stove vents tend to accumulate lots of debris that causes them to become constricted.