Bought a new washer+dryer. Old washer+dryer are still working fine, so I figured I will keep the old dryer and just dispose of the old top load washer (the new one is a nice front load). They're both electric, so I don't have to worry about gas plumbing.

Do I need a separate vent pipe for each dryer? Or can they just "share" a single vent pipe, via a "Y-pipe?"

  • 2
    You plan on using them at the same time? And you had a new electric circuit installed for the second dryer?
    – JPhi1618
    Oct 15, 2015 at 19:58
  • 1
    I totally forgot that I would need a separate breaker switch for another dryer! I might dispose of it it becomes too much work
    – Rollo R
    Oct 15, 2015 at 20:17

1 Answer 1


A dryer moves a lot of air, and requires a dedicated 4" vent. For two dryers to operate at the same time, you would need a 6" vent. Just as air conditioning ducting gets smaller as it splits off, the two outgoing vents will need to join into a larger vent.

The area of a 4" vent is (πr^2 = 3.14 * 2 * 2 = ) 12.6 sq in. A 6" vent is 28.3 sq in. so it can handle the two 4" vents (you wouldn't have to double the vent size to 8"...).

Combine this with the need for an additional electric run, and your spare dryer is turning into a big expense!

  • 1
    I checked the installation manual for several popular brands. They all require the use of a back draft damper for each unit when venting multiple dryers in a common duct. ( another expense)
    – mikes
    Oct 16, 2015 at 1:36
  • 1
    Another expense and another joint for lint to get stuck on.... It's not looking good.
    – JPhi1618
    Oct 16, 2015 at 2:04

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