Odor Transfer! Help!

[BretyboyOO]

Hey all,
This is my first time on here so please excuse me if I sound a little "new". I have a client who owns a multi-tenant residential building where the tenants are complaining of odor transfer. Each apartment on the "G" line, floors 1 through 12, seems to experience the same odors at the same time. Each "G" line apartment is served by one central bathroom exhaust system and one central kitchen exhaust fan. I ran some airflow tests and found that while the kitchen exhaust system seems to work fine under all conditions, the bathroom exhaust on many of the apartments actually "SUPPLIES" air under certain conditions. Specifically, when the front door leading to the corridor is closed, and all the windows are closed, the bathroom exhaust diffuser actually "supplies" air into the bathroom. However when the front/corridor door or windows are open, the bathroom diffuser then exhausts air, as it should. This is no doubt the cause to the odor transfer, but I am uncertain on what's causing it and how to control it. Could the kitchen exhaust be stronger than the bathroom exhaust so that when I "seal" the apartment shut the kitchen actually pulls air out of the bathroom exhaust? If I recommend a stronger bathroom fan, do I risk creating the same problem in the kitchen? Or, will the problem persist as long as I don't have sufficient make up air entering each apartment? (Keep in mind, when I open the door to the corridor or windows, both fans exhaust normally) If so, how do I introduce makeup air into the apartment? Undercut corridor doors? Any help or advise is greatly appreciated!

 

[trashcanman]

It sounds like the fans are getting their air any way they can. They will not pull a vacuum.
1. Provide backdraft dampers at toilet exhaust and kitchen exhaust (unless the kitchen is exhausting greasy air).
2. Provide adequate makeup air for both systems. Do they run at the same time?
3. A test and balance should be done by a reliable T & B firm to see what is going on.

 

[Drazen]

if i understand well, you are talking about door to common corridor, i.e. main apartment door?

if that is so, yes, i would also believe kitchen exhaust draw the air from bathroom as there is no make up air.

i would tend to make make-up grill in kitchen, as close to kitchen hood as possible to make that flow localized. that grill would have provision for closing, like drive, and should be best linked with hood, to open when hood damper is open.

 

[urgross]

Smoke testing under the bathroom door should be able to give a quick idea of what is happening, or placing a dP across the perimeter.

Are the exhuast fans both constant volume and the supply also constant volume? A volumetric balance, or testing with a flow hood, under closed door and open door should be indicative.

Can the doors be undercut?

 

[ChasBean1]

I think Part 1 of the issue is that the building exhaust air probably exceeds the make-up air. This is only a guess based on what I’ve seen in ± 97 percent of these types of buildings.

Part 2 of the issue is that the bathroom exhaust might have a damper that operates based on a light switch, and the damper is clogged with dust and doesn’t move.

The TX fan operation might also need to be verified.

You might need a professional to review the drawings and field verify operation. These types of issues are not unique to your installation.