Two dryers connected to the same exhaust via a “Y”. Backdraft problems?

Question

I have two dryers (one gas, one electric) and their exhaust pipes are merged with a "Y" to a common exterior exhaust. I'd like to keep it that way to minimize cuts through the wall (and eventually I may get rid of the old electric dryer).

The new gas dryer is 15 feet away from the wall, the old one is close to it (and to the "Y").

Question: there's a bit of back draft when the gas dryer is working. I can smell it when I'm around that old electric dryer. Can I install some sort of backdraft preventer? Is there such a thing?

Answer 1

@Peter: I think you answered your own question in your comment to ChrisF. What you want is an "inline draft blocker." And you'll want two, one for each dryer. Here are a few on Amazon:

http://www.amazon.com/Lambro-Industries-Blocker-1775L-Accessories/dp/B000H5PTJA/ref=sr_1_1?ie=UTF8&s=hi&qid=1304804320&sr=1-1

http://www.amazon.com/DEFLECTO-BD04-Draft-Blocker/dp/B00009W3HB/ref=pd_cp_hi_2

http://www.amazon.com/Dundas-Jafine-DB4ZW-Dryer-Blocker/dp/B000DZDPPE/ref=sr_1_34?s=hi&ie=UTF8&qid=1304804226&sr=1-34

Answer 2

I don't know whether you can get them to fit inside an exhaust pipe, but you can get one-way grilles/vents for the outlet.

These have a series of flaps that can swing one way only - outwards - so when the hot air is blowing out they flip up, but they get forced closed when blown from the outside.

If you could fit something like that between each dryer and the "Y" then this would solve your problem.

This is a picture of what I mean:

Obviously this won't work as the grille wont fit in line, but it shows the flaps.