B-vent maximum height

Had a new construction 2-story home where the water heater was stored in the garage. The B-vent was was ran through the structure and through the 2nd-story roof for a total height of roughly 17 feet. I don’t see any limitations in the code for maximum vertical length of B-vents. Is there an industry standard?

It depends on the appliance, do you have a model of the unit? In general 2 stories are done this way all the time. The taller the vent/chimney the better draft.

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Bradford White, 2022, model #RG250T6N.

Bradford White Water Heater Manuals | Water Heater Hub.

It should be braced at 5 feet, or so.

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Looks like 49.33 inches from Minnesota!

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Consider issues:

  • Some appliances have a minimum chimney length, to create proper draft. The manual for the appliance is the only source for that. This is measured from the appliance, not from the roof.

  • There’s a minimum height based on the slope of the roof.

  • The maximum is dictated by common sense and bracing. Too high is more vulnerable to wind and damage, and to excessive cooling of the flue gases which could lead to downdrafts.

In short there’s a sweet spot, and those look kinda crazy tall. A simple B-Vent should not be so tall to require bracing, except in weird circumstances.

For a table see:
https://inspectapedia.com/chimneys/B-Vent-Chimney-Rooftop-Clearances.php