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Clothes Dryer Exhaust - Makeup Air

Dominic

SAWHORSE
Joined
Jun 20, 2017
Messages
49
Location
Albany
Section 504.6 states "Makeup air. Installations exhausting more than 200 cfm (0.09 m3 /s) shall be provided with makeup air."

The laundry room I am designing will have 3 dryers which triggers 504.6. The engineer is telling me there is no off the shelf make-up air unit so he will need to design one. His design would be variable speed and tied to the quantity of dryers running. This is an expensive little sytem for a 3 dryer laundry room.

Has anyone run into and has an economical solultion?

There is an opperable window in the room. Can we say the window is our point of make-up air? Code does not specifically state mechanical means of makeup air.

I am interested to see how others dealt with this.

Thank you in advance.

 
What kind of setting
House, apartment, business, other?

one story or multi ?
 
I am not ok with the window option. The ventilator is a good solution. Just trying to find a perfect solution.

I think the best solution is to install heat pump dryers and call it a day.
 
I would say you still need some sort of control system to start and stop the fan(s) with the dryers, unless you rely on the occupants using the dryer to start the fan(s).

Without conditioning the outside air, you could be drastically raising or lowering the air temperature and raising the humidity of the room.
 
Assuming these are electric clothes dryers and makeup air is the only issue ....

Here's my thoughts .... provide exterior wall opening and a motorized damper (sealed well so we don't offend the energy folks too terribly much). Interlock each dryer to the motorized damper so if one operates, damper opens. Provide electric unit heaters to keep temps up during the winter. A/C wouldn't be required or necessary in the summer, at least not for the functionality of the clothes dryer. If you want comfort, you could provide A/C. Make sure walls are well insulated :)
 
Assuming these are electric clothes dryers and makeup air is the only issue ....

Here's my thoughts .... provide exterior wall opening and a motorized damper (sealed well so we don't offend the energy folks too terribly much). Interlock each dryer to the motorized damper so if one operates, damper opens....
I like the motorized dampers idea but why not go one step further and have them operate based on pressure differential between the room with the neighboring room/hallway? It probably would necessary to provide makeup air if only 1 of them was running.
 
I live and design in a mostly temperate climate (southern California). Most of the apartments developers I work with make the common laundry room an unconditioned space. they put a barometric backdraft-style louvered damper on the exterior wall and they're done.
 
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