Grease Duct Enclosure Termination

[fatboy]

We have a new steak house going into an old building. The grease duct has been routed through the building, penetrates an exterior wall at the top of first floor, goes up the side of the building to the third floor where it the goes back onto the roof and exhausts. The contractor terminated the duct enclosure (wrap) where it exits the building at the first floor. At final my inspectors call the contractor on it, citing 2012 IMC 506.3.11.2, which states the enclosure must be continous to the outlet terminal. The engineer is claiming the outlet terminal is where the duct exits the building, not the exhaust outlet. I know they need to protect it as required by 506.2, and part of me has trouble with requiring the wrap on the exterior of the building, but I think the outlet terminal is the point of exhaust. Opinions?

 

[cda]

Sorry hate to say, I have to agree with an engineer

Thank about even when it goes straight up and you have say three feet of duct above the roof line, that three feet is not protected

Yes I have seen your set up before with no protection

Now do not know if you had a property line near, if that would change the answer

 

[Codegeek]

Since the purpose of the grease duct enclosure is to protect other areas of the building from the spread of smoke and fire from the kitchen, I'd say once it penetrates the exterior wall, it's reached the outlet terminal. If you believe the installation is not achieving providing for this protection, then I think you may have an argument. Otherwise I think the engineer is correct.

 

[north star]

$ = = $

What about Section 506.3.11. [ `12 IMC ]......506.3.11 Grease duct enclosures.

"A grease duct serving a Type I hood that penetrates a ceiling, wall, floor or any

concealed spaces shall be enclosed from the point of penetration to the outlet

terminal." ?



= $ $ =

 

[fatboy]

That was the question.....what constitutes the "outlet terminal"?

I had pretty much worked myself into accepting the installation, as long as they protect it as 506.2 requires. Just wanted some reinforcement that I was looking at it as in under the intent of the code.

 

[mtlogcabin]

Question

1 is the exterior of the building combustible and is there sufficient clearance from combustibles?

2 It gets pretty cold on Colorado will the duct maintain sufficient temps and keep excessive build up of grease on the inside?

 

[fatboy]

Non-combustible construction, 3" separation. The temp question was raised with the engineer, he said at the velocity they are moving the air, it will only be in that part of the duct 4-5 seconds.

 

[north star]

= =

fatboy,

Im my simple mind, an exhaust "outlet terminal" would be where the duct stops

[ i.e. - stops / ends ].

Also, I'm thinking along the lines of **mtlogcabin** as well, ...the congealing

of F.O.G. in that vertical duct.

= =

 

[north star]

# #

So the question becomes, ...is the "wrap" required for thermal protection

of the duct system [ on the exterior, ...in colder climates ], as well as,

protection from combustible surfaces ?

# #

 

[cda]

Well you install a rated shaft or wrap

Are you trying to protect the building from the duck or the ducks from the building??

Come on get your ducks in a row

 

[klarenbeek]

I agree with north star. Outlet TERMINAL would mean where the duct ends. The reason for the code change was based on the listing of the grease duct wrap. It was never actually listed to only wrap just portions of the duct for clearance reduction only.

Perhaps the contractor could avoid the problem by using the shaft enclosure in section 506.3.11.1. I haven't seen it used in years, but it is an option.

 

[cda]

So is the base of the exhaust fan the terminal?

And everything below that is duct work???

So on this one do you wrap it to the base of the fan??????

http://www.michiganexhaustcleaning.com/neglected_coney_island_exhaust_fan.jpg

 

[north star]

+ + +

"So is the base of the exhaust fan the terminal?"

Where the ductwork actually stops/end is the termination point [ i.e. - the terminal ].

"So on this one do you wrap it to the base of the fan??????"

Section 506.3.11 [ from the `12 IMC ] requires that all duct work be enclosed, not necessarily"wrapped" per se', except, Section 506.3.11.4 does not require enclosure......From Section

506.3.11.4 - Duct enclosure not required: "A duct enclosure shall not be required for

a grease duct that penetrates only a nonfire-resistance-rated roof/ceiling assembly."

**cda**,

In your picture, that exhaust outlet does not appear to be 40 inches above the roof surface.

[ RE: Section 506.3.13.1 Termination above the roof. "Exhaust outlets that terminate above

the roof shall have the discharge opening located not less than 40 inches (1016 mm) above the roof

surface."......Am I just seeing it wrong?



+ + +

 

[cda]

+ + +

Where the ductwork actually stops/end is the termination point [ i.e. - the terminal ].



Section 506.3.11 [ from the `12 IMC ] requires that all duct work be enclosed, not necessarily

"wrapped" per se', except, Section 506.3.11.4 does not require enclosure......From Section

506.3.11.4 - Duct enclosure not required: "A duct enclosure shall not be required for

a grease duct that penetrates only a nonfire-resistance-rated roof/ceiling assembly."

**cda**,

In your picture, that exhaust outlet does not appear to be 40 inches above the roof surface.

[ RE: Section 506.3.13.1 Termination above the roof. "Exhaust outlets that terminate above

the roof shall have the discharge opening located not less than 40 inches (1016 mm) above the roof

surface."......Am I just seeing it wrong?



+ + +

S

I do not know, one of them Internet things

To me in that picture the duct ends at the bottom of the fan

 

[fireguy]

While not part of the code, an exhaust system must be cleaned, to remove combustable grease. If that duct is away from the building, how far would be comfortble leaning over the edge of the building. Now think about doing that at 2:00 AM, ice on the roof.

Back to the code. A fan is to be hinged so the fan and duct can be cleaned of the grease. NFPA 96-2011-11.6.2 Hoods, grease removal devices, fans, ducts, and other appurtances shall be cleaed to remove combustable contaminants jprior to surfaces becoming heavily contaminiated with grease or oily sludge. Defining depth of contaminants is A.11.6.2, grease should be cleaned to 0.002 " depth.

No way would I accept a job, knowing the duct and fan is not accessable. And having to lean over the edge of the roof is not accessable.

 

[cda]

Op

Appears to state that the exhaust fan winds up on the roof

 

[Codegeek]

Fatboy, I would contact Sam Dardano since he's from your neck of the woods and very involved in the IMC. See what he has to say about it.

 

[fatboy]

Yeah I thought of that also, I will be seeing him Friday for our Chapter meeting, he is presenting.

I also have an interp request in with the ICC.

Thanks all........

 

[cda]

so they wrap the outside duct work.

How long is that going to stand up to the weather??

and once again why is the wrap there in the first place?? what are you trying to protect

 

[cda]

if you have a handbook it shows that the wrap or shaft ends at the roof line

 

[fatboy]

yes it does, on both illustrations.................

 

[cda]

View attachment 676

OpIs this kind of what they are proposing ???Sorry about the orientation And someone wants a shaft or wrap from where it comes out of the building all the way to the fan???View attachment 676

/monthly_2013_02/image.jpg.191503633b33dbf339c808f39ac25c5e.jpg

 

[fatboy]

Exactly.......and the someone was my inspectors, but then I had some heartburn with it. BTW, the building is masonry, and the duct has the required 3" separation. I'm still waiting on an interp from ICC.

BTW, seldom do I question my inspectors, but based on the responses here, it is not a clearly written section. Can someone say, code change?

 

[cda]

Exactly.......and the someone was my inspectors, but then I had some heartburn with it. BTW, the building is masonry, and the duct has the required 3" separation. I'm still waiting on an interp from ICC.BTW, seldom do I question my inspectors, but based on the responses here, it is not a clearly written section. Can someone say, code change?

My boss questions my calls all the time.

Of course I give him good reason to