Residential Kitchen exhaust mixed with rest room exhaust

[Jabba007]

I am working on a 7 story mixed use building, including residential apartments and condos as well as retail and office space. I am getting pressure to combine the residential kitchen hood exhaust with the restroom exhaust. The plan is for a combined exhaust system with an exhaust fan at it's termination that will run continuously, with smaller, point of use fans also connected to the system, like the "fart farns" that are used in restrooms. These smaller fans will create more airflow when they are on, and still allow continuous exhaust as well.

I have not been able to cite anywhere in the code that prohibits mixing these exhausts. Does anyone have any experience here?

Thanks in advance for your help!

Jabba

 

[walkes]

Our codes in Canada only allow the interconnection of washroom exhaust with general exhaust at the fan inlet. There should also be a backdraft damper on the general side to prevent odours from migrating in the event of a fan failure.

 

[GMcD]

As Walkes has pointed out- it depends on your local Codes and what the local Code Authority will accept. Technically I don't see a problem as long as the little bathroom fans have a backdraft damper on their discharge, ditto for the range hoods in the kitchens. The exhaust shaft can be considered an "extended plenum" and can comply with Codes that say you can only combine toilet exhaust with general exhaust "at the inlet plenum to the exhaust fan". The vertical duct shaft can be considered the "extended plenum". I think it's a lot better than the standard practice I see where individual suite exhausts are terminated at exterior wall caps right over, under or beside openable windows.....

 

[willard3]

In New York, this a code violation.

Kitchen exhaust, residential or commercial, contains grease and grease is flammable.

snip
The plan is for a combined exhaust system with an exhaust fan at it's termination that will run continuously, with smaller, point of use fans also connected to the system, like the "fart farns" that are used in restrooms. These smaller fans will create more airflow when they are on, and still allow continuous exhaust as well.
snip

Fans in series as you envision are very, very tricky to control and you are going to have some nasty surprises if you do this.