# Kitchen Type 1 hood duct with Type 2 hood duct tied in



## earshavewalls (May 24, 2010)

I have a plan submitted where the mechanical engineer is proposing to tie in a Type 2 hood (serving a high-temp dishwasher) to the Type 1 hood grease duct system so they don't have to make another shaft to go through the second floor to the roof.

I don't think this is allowed. I have never seen anyone even suggest this before, so this is the first time I have had to research this issue. It seems to me that (this is California Codes, so look out) CMC Section 510.1.3 applies when it states: "Duct systme shall not be interconnected with any other building ventilation or exhaust system."

I feel that a grease duct system is different than a steam exhaust system, but I am wondering if this is only MY opinion or is it an accurate interpretation of the code.

This must be an easy question for someone out there.........I hope.....

Thanks


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## cda (May 24, 2010)

check nfpa 90??

Type I exhaust ducts shall be independent of all other exhaust systems except as provided in Section 506.3.5. Commercial kitchen duct systems serving Type I hoods shall be designed, constructed and installed in accordance with Sections 506.3.1 through 506.3.12.3.

506.3.5 Separation of grease duct system.

A separate grease duct system shall be provided for each Type I hood. A separate grease duct system is not required where all of the following conditions are met:

1.   All interconnected hoods are located within the same story.

2.   All interconnected hoods are located within the same room or in adjoining rooms.

3.   Interconnecting ducts do not penetrate assemblies required to be fire-resistance rated.

4.   The grease duct system does not serve solid fuel-fired appliances.


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## Builder Bob (May 25, 2010)

The answer seperate grease duct system ---- Steam does not equal grease. (Clarification of CDA's post IMHO)


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## Glennman CBO (May 25, 2010)

Agree with cda and Bob. It is neither code, nor feasable, nor practical. A grease system and a steam system do not mix.


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## north star (May 25, 2010)

** * * ** 

*WW,*



*Might as well throw my 2 cents in here and concur with the others.*

*Can't mix **the two separate types of exhaust systems.*

** * * **


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## klarenbeek (May 25, 2010)

I agree also.  Fire waiting to happen.  The duct to the dishwasher wil get grease into it but you know it won't get cleaned like the welded grease duct.  Some will come out due to the steam, but then it will run back to the dishwasher, dripping all over it.


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## earshavewalls (May 25, 2010)

Thanks, all. I felt the same, just couldn't find specific wording in the code (California code, of course).......it would be a much easier life for all if California just adopted the I-codes and got with the program.........JMHO.

Thanks again...


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## Glennman CBO (May 26, 2010)

Ear,

It sounds to me like the code section you quoted covered it.


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