Thread: Wrong furnace flue instalaltion?

Never saw this type of flue cap before. This was a brand new home and it had 2 of these. They were single wall design, each about 3' long. The flues were proper B vent types until they entered these roof caps. The B vent only extended about 1 foot into the roof sections. They were not otherwise attached or sealed, and there was a gap around it between the top of the B vent and the inside wall of the cap. My concern is that condensation may occur on the single wall part above the termination of the B vent. It would then rain down back into the attic.

I read the furnace installation instructions on site which only said to use a "manufactured" flue and roof cap rated for the purpose.

Anyone know if these are OK?

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Keven,

Link shows similar vent termination start of page 10.

www.ventingpipe.com/catalogs/Simpson/Bvent.pdf

I was not able to open Billy's attachment so I'm commenting without knowing what was in it. No single wall vent should be used outside of the appliance's room or area. Also, I see no flashing detail where the vent penetrates the roof.

One other comment - it's commonly misused but the "flue" is the space inside the vent or chimney liner. It's not a component or "thing."

Originally Posted by Eric Barker

I was not able to open Billy's attachment so I'm commenting without knowing what was in it. No single wall vent should be used outside of the appliance's room or area. Also, I see no flashing detail where the vent penetrates the roof.

One other comment - it's commonly misused but the "flue" is the space inside the vent or chimney liner. It's not a component or "thing."

Eric--Guilty as charged on the misuse of "flue." However, it's what my clients understand. When I talk about vents they seem to think in terms of intake, not exhaust, so I've gotten sloppy. I should have known better than to post the question that way here.

The flashing is fine at the roof; it's a soldered galvanized base similar to a plumbing roof jack. No problems there.

The Simpson info Billy posted (thanks, Billy) gives their blessing to a similar design. It shows the top of the B vent section ending about 1.5" to 3" above a base flashing. There is no base flashing in my example, but the overall concept is similar. Seems strange to me, but the double wall does not have to extend to the top.

Originally Posted by Eric Barker

I was not able to open Billy's attachment so I'm commenting without knowing what was in it. No single wall vent should be used outside of the appliance's room or area. Also, I see no flashing detail where the vent penetrates the roof.

One other comment - it's commonly misused but the "flue" is the space inside the vent or chimney liner. It's not a component or "thing."

Eric,

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Originally Posted by Kevin Barre

The flashing is fine at the roof; it's a soldered galvanized base similar to a plumbing roof jack. No problems there.

Are you sure? It looks like that vent just comes up out of the roof. I cannot imagine that is an approved flashing. I've seen the ones you are referring to, some are shown in the link Billy posted.

The Simpson info Billy posted (thanks, Billy) gives their blessing to a similar design. It shows the top of the B vent section ending about 1.5" to 3" above a base flashing. There is no base flashing in my example, but the overall concept is similar.

Actually, it is quite different.

Those made by Simpson in that link (and made by others as well) have ventilated sides. Those are 'high wind area' Type B Gas Vent Caps. The one in your photo is nothing like those - no ventilated sides, just a flat deflector above the vent opening with open top and bottom. Were you able to get on the roof? What did it say on the cap? All the approved Type B gas vent caps I've seen state Type B Gas Vent Cap on them.

This is an unlisted single walled sleeve over B-vent and should be removed. They should have installed the mfrs listed roof flashing as well. This is probably technically an unlisted "shroud".

If you don't see a listing sticker on the pipe, then I recommend you write it up as suspicious and possibly unlisted for that application.

HTH,
Bob

Originally Posted by Jerry Peck

Those made by Simpson in that link (and made by others as well) have ventilated sides. Those are 'high wind area' Type B Gas Vent Caps. The one in your photo is nothing like those - no ventilated sides, just a flat deflector above the vent opening with open top and bottom.

Originally Posted by Bob Harper

This is an unlisted single walled sleeve over B-vent and should be removed. They should have installed the mfrs listed roof flashing as well. This is probably technically an unlisted "shroud".

If you don't see a listing sticker on the pipe, then I recommend you write it up as suspicious and possibly unlisted for that application.

HTH,
Bob

Thanks for the post Bob,

What was the giveaway?

Mr. Peck,

Hart & Cooley make a High Wind area vent cap with out ventilated sides.

Take another look at the pic guys... I think the flashing might be in place. The picture is taken and a very flat angle in relation to the roof and it kind of blends in with the shingles. I think it's there.... it's tough to say for sure.

Originally Posted by Jerry Peck

Are you sure? It looks like that vent just comes up out of the roof. I cannot imagine that is an approved flashing. I've seen the ones you are referring to, some are shown in the link Billy posted.

I could see the base of the flashing from inside the attic, and I could see it from outside using binoculars. It's a flat base flashing (made to the correct pitch) with the vertical section carefully soldered to it. While it obviously took a lot of time to make, I suspect it was made locally or may be old stock. That's why I had the questions. But it wasn't leaking, and it maintains plenty of clearance around combustibles.Those aren't concerns.

Actually, it is quite different.

Those made by Simpson in that link (and made by others as well) have ventilated sides. Those are 'high wind area' Type B Gas Vent Caps. The one in your photo is nothing like those - no ventilated sides, just a flat deflector above the vent opening with open top and bottom. Were you able to get on the roof? What did it say on the cap? All the approved Type B gas vent caps I've seen state Type B Gas Vent Cap on them.

As for getting on the roof, the roof pitch was a 9 in 12, and it had been raining. Much as I wanted to, I'm not crazy enough to get up on a roof in those conditions! My concern isn't the weather-tightness of the base, it's the rest of it.
Not that I'm doubting you if you've seen the "high wind area" type you describe, but in the Simpson info their wording does not mention any special high wind applications...they merely call the design a "combination" top. Simpson seems to tout it as an inexpensive method. In any case, their drawings clearly show the B vent terminating well below the cap. That's my real concern/question.

Not that is matters, but the local AHJ has passed it. I have no problem writing it up, but I want solid backing for my position to deflect the inevitable calls from the builder and/or HVAC contractor. I can't just say "I've never seen one like it on anything less that 30 years old."

Kevin,

If Bob Harper said it's unrated, IT is unrated.

Hopefully He'll have time to expand why.

Originally Posted by Kevin Barre

It's a flat base flashing (made to the correct pitch) with the vertical section carefully soldered to it. While it obviously took a lot of time to make, I suspect it was made locally

Which would mean it was not a listed flashing for use with a Type B gas vent.

I believe those are required to turn up a certain amount and have a storm collar (thinking to what they look like at the top of a chimney, and, if that was not an approved flashing, it should at least meet those requirements). Wind moving that thing around is going to break soldered joints apart.

A listed flashing allows the inspector to see both top and bottom that there is clearance to combustibles. Also as noted, some factory built vents and chimneys require a gap or slots at the top of the flashing cone to allow for cooling.

That smooth pipe does not have the bead rolls of B-vent. Also, by info. provided, the B-vent is short. There should be a listed termination. If a vent is over 5 ft through the roof, it should be supported such as with struts or guy wires.

IF you don't see listing stickers on each section and component, call it out as suspicious. The rest of the B-vent should be visible in the attic or Combustion Appliance Zone but not always accesible.

HTH,
Bob

Hi Billy,

Thanks for the Adobe link. I went to see what version I have which is the 8.1.1.

When I opened it, it went into it's upgrade routine - ????

I went back to your attachment and it now opens. So I have no idea what was wrong but it now works. Strange because I have not been having grief with PDFs.


Thanks again.

Thanks to all for the replies. I did write it up as being most likely a non-listed component and I recommended an assessment and repairs as necessary by a licensed HVAC installer -- and not the same one that installed it! As I said, the clearance to combustibles was not an issue. That was all clearly visible from the attic. The furnace was easily accessible as was the B vent up to the roof--you could walk right up to it.
The strength and wind resistance of the assembly wasn't an issue either. The vertical section had tabs forming a flange and they were carefully folded back and soldered to the underside of the base, as well as around the perimeter of the opening on the top side. The base was made to the exact slope of the roof so the vent stood plumb.
I can't imagine anything short of a tornado tearing it off, and any other conventional flashings would be gone at that point also. Along with your turbine vents and everything else.

Eric,

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