Multi Dryers Vent System

[Mike Lamb]

Does anyone have a chart or some reference for the sizing or layout of a collective vent being used for multiple clothes dryers? The dryer in this unit is electric but I can't vouch for the other units.

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[Steven Hockstein]

I would tell my client that they should have an independent dryer vent for each dryer.

Lots of reasons but here are a few:

The lint will drop down and clog ducts below.

The fumes from below can enter into the upper dryer vent duct.

Added the lint build-up.

90 degree connection is much less efficient for air flow.

Also-the cheapo vent duct is going to collect lint and I would recommend that they use a metal duct with smooth walls.

On the positive side I have had the opportunity to design two brand new houses because the original houses burned to the ground because of dryer vent fires. Luckily, nobody was injured.

[Mike Lamb]

Steve, that may not be practical for large multi-units.

I have been tooling around the Internet and have come up with a couple things.

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This is from the International Mechanical Code 2009-504.8

Common exhaust systems for clothes dryers located in multistory structures.

5. The exhaust fan motor design shall be in accordance with Section 503.2.

6. The exhaust fan motor shall be located outside of

the airstream.

7. The exhaust fan shall run continuously, and shall

be connected to a standby power source.

8. Exhaust fan operation shall be monitored in an

approved location and shall initiate an audible or

visual signal when the fan is not in operation

Does this suggest that a fan is required?

[Steven Hockstein]

I thought it was in a multi-family house, not an apartment building. I don't know the specific rules or the equipment required. I know that make-up air is especially important if there is a fan continuously pulling the air. Did you check to see if there is air being pulled from the duct?