2012 IMC Kitchen Ventilation Question

[Ziggypump]

I'm hoping someone can help me in understanding or looking at this issue another way. Per the IMC 2012 (which I have to use) Kitchens/cooking have a note b on table 403.3. Note b states that, "Mechanical exhaust required and the recirculation of air from such spaces is prohibited (see seciton 403.2.1, Item 3)." 403.2.1, Item 3 in essence says that all air supplied to spaces with note b, as indicated in table 403.3, must be exhausted. This includes code minimum and any extra supplied.

This is all well and good if we are just supplying make-up air, but space conditioning of the kitchen is requested by the owner. They want a separate rooftop unit to condition the air. That would mean the make-up air unit would only supply air to the exhaust hood supply plenum, and the rest of the make-up air would come from a separate rooftop and from adjacent spaces (need to keep this kitchen negative).

The way I see the code, a rooftop unit to condition the space would not be allowed as that is returning air. But returning and supplying air to the same space shouldn't cause too many problems. What are your thoughts on the code interpretation?

 

[dbill74]

By your reasoning (and I see no fault in it), you would need to provide a 100% OA unit to provide conditioning for the kitchen.
However, reading through a commentary of the IMC I have about 403.2.1 Item 3, I find that the intent of this item does not prohibit conditioning air from being recirculated within the same space. The key point and intent of this line is that the AHU serving a kitchen can serve only the kitchen, it is not allowed to also serve the dining area, bathrooms, etc.

Wouldn't hurt to contact and see how the AHJ interprets this.

 

[Ziggypump]

I believe the intent too except for the "All air supplied to such spaces shall be exhausted, including any air in excess of that required by Table 403.3." It's this line that is throwing me. It doesn't say anything about Outside air, it says Supply air. I do have the question into the AHJ, but this is by secondary means of information while I wait.

thanks,

 

[DBronson]

Ziggypump:

If you follow the link and scroll down to "Application Information", download the "Kitchen Ventilation Systems- Application Design Guide". There's a good discussion of this topic in that publication.


Link

Regards,

DB

 

[chicopee]

If you want to conserve air conditioning within the kitchen, you should do research on push-pull ventilation system over cooking appliances. About 30 years ago, I came across such a system for a golf course club house in Connecticut. It was expensive but I guess it paid for itself I would say within a 10 years time.