Metal Chimney

[NewInspector]

My question is how to tell if an exterior metal chimney is rated for exterior use. I am new to the field & during my training came across this one. Would the info typically be included w/the other stamped info? This was a waterfront home built in the 1950's. Also, are there any restrictions as to the proximity of this type of chimney & a deck.

RDH

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[hausdok]

Those are typically exposed to the weather when the protrude from a roof plane, so this isn't any different. It's okay. You just need to ensure a 1-inch clearance to combustibles.

Did it have the necessary height above the ridge? From this angle, it looks like it extends more than 3ft. above the roof, so you might have a guy wire requirement. Check with your local AHJ to see what's required in your parts.

OT - OF!!!

M.

[kurt]

What about excessive condensation in the flue? I think there's a restriction on length of run; B vents are a mess in Chicago in winter if you run them outside the building.

[Jim Katen]

My question is how to tell if an exterior metal chimney is rated for exterior use. I am new to the field & during my training came across this one. Would the info typically be included w/the other stamped info? This was a waterfront home built in the 1950's. Also, are there any restrictions as to the proximity of this type of chimney & a deck.

It's not a chimney. It's a b-vent.

B-vents are rated for exterior use.

Running them outside for long distances can cause problems during cold weather because the exhaust gases get cold before they reach the top and the draft becomes sluggish.

The vent requires 1" clearance to combustibles. Other than that, there's no reason it can't pass by a deck.

- Jim Katen, Oregon

[hausdok]

Hi Again,

Yeah Kurt, that's a good point, but around here they're typically installed on furnaces in unheated garages and they pass directly up through the garage roof to the outside. Sometimes they pass through heavily insulated and well-ventilated attics where the temperatures aren't that much different from outside. They do get some condensation, but nothing on the order of what you'll see in Chicago with your temps or in Mass where he is.

OT - OF!!!

M.

[NewInspector]

I found this on the manufacturers website. I don't know if the practice of creating a chase is actually practiced, but it does seem to be preferred/recommended below the roofline.

http://www.selkirkcanada.com/products/v ... 202004.pdf

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[NewInspector]

Thanks for all the responses. My next question would be for the code gurus. Does the code address this issue?

RDH

Quote: By misfortune was my life prolonged, so that I may tell sad stories of my own mishaps. - Silas Marner

[Jim Katen]

Originally posted by NewInspector

Thanks for all the responses. My next question would be for the code gurus. Does the code address this issue?

G2427.6.1 Installation, general. Gas vents shall be installed in accordance with the terms of their listings and the manufacturer's instructions.

G2428.2.9 Chimney and vent locations. Tables G2428.2(1) and G2428.2(2) shall be used for chimneys and vents not exposed to the outdoors below the roof line. . .

- Jim Katen, Oregon

[NewInspector]

THX JIM.

[Eric B]

I have found it necessary to explain the water stain cause to the client. Too often the HVAC contractor will blame them on a roof leak.