Two clothes dryers sharing a common vent??!

[jamckelvey]

Just bought a 2-flat that we are (slowly) converting into a single-family. Property came complete with two clothes washers and dryers. Both dryer exhausts share a common vent line to the outside. This doesn't seem right to me since either unit will create a back-pressure on the other when operating. I'm going to rework the vent system so that each has its own dedicated vent/outdoor exhaust terminal but in the mean time, I am curious to know if common venting is incorrect/code-illegal and/or unsafe.

Thanks!
Jim

 

[Jadnashua]

It could be very unsafe, especially if these are gas dryers...if there was any restriction, you could be blowing into the other area, not counting lint, etc. There could be dampers in-line, but they also add restrictions that will increase the drying time and cost you money. Minimize the elbows, use smooth wall duct (not the corregated stuff) to minimize restrictions and save money in the long term. Avoid screws in the duct to minimize lint buildup.

 

[Sponsor]

 

[jamckelvey]

FYI-No dampers. Doesn't change things, but no dampers.

 

[Jadnashua]

I wouldn't want to use dampers, as they would provide some restrictions...restrictions on a dryer equate to longer running time, lint catchers (dangerous), and potential feedback loops of the exhaust. Run separate exhaust and ducts...

 

[Lakee911]

If you're converting to a single family, why do you need two dryers?

 

[Geniescience]

To answer the original question, i think it's totally NOT code to let air flow back into someone else's dryer. And that is what happens when air can go both ways. One way is to the outside, one other way is over into the dryer next door. Air doesn't care.

If you want to keep both dryers on one vent, I would recommend a flapper backstopper, knowing that it has its own problem which can be dealt with during regular maintenance. Cleaning it off.

Jim, what Jim deB pointed out about feedback loops is even more true when your two living units are open to each other. Air will come tumbling out of one dryer to feed the air removed by the dryer that is on. All the more reason to prevent backflow. If you must keep both dryers and if you won't have two separate vent lines.

David