Clogged Roof Dryer Vent

[Buckeroo]

Help! My gas dryer is in the center of my ranch house and vents through the roof. The total run of the duct is about 30 feet, and I've recently had all but the short section (3 ft.) between the dryer and the wall replaced with hard duct. Since then, lint collects very quickly on the screen at the roof exhaust, and I have to climb on the roof to clean it out about 3 times a month! Any suggestions for letting the lint pass but keeping critters out?

[Hube]

There is no need for this "screen" at the point ot of exiting.
You should have weather tight "flapper at the exiting point so when the dryer is off this flapper will close .
A screen is just asking to be clogged.
Also, make sure your lint filter in the Dryer is cleaned and tightly secured after EVERY load of clothes.

[Buckeroo]

Thank you, Hube. My house is 40 years old, and the roof cap doesn't have a flapper. I've seen a couple of caps on-line from Broan and Deflect-o that look like they would be good replacements. Perhaps I'll get ambitious, and attempt to replace it myself! In the meantime, I've removed the screen, and I'm taking my chances with the squirrels and the birds.

[LazyPup]

Even with hard duct 30 ft is really pushing the limits on a drier vent, especially if there is a substantial vertical rise. By the time the air gets to the outlet it may not have sufficient velocity to open a flapper vent adequately. The end result would still be an excessive amount of lint buildup. You may need to install an induced draft fan on the input end of the duct and tie the drier in on tee above the fan.

[Hube]

The shorter the run, the better, but a 30 ft. dryer vent run should still have sufficient velocity to open a properly designed back-draft damper. If the the discharge diam. is 4" and has less than 3 -90's installed in the run, the "equivalent footage " is still within range to enable the velocity of the discharge to open this damper.

[Buckeroo]

Now that I've removed the roof screen my dryer is working beautifully. I haven't yet installed a new roof cap with a flapper, but I plan to. It seems that the air has plenty of velocity as it exhausts through the roof, because the vent is now ejecting tufts of lint into my backyard! It surprises me how much lint gets past the screen in my dryer. I think that I'm going to clean it out and make sure that my lint screen is situated properly.

[LazyPup]

I would not install a flapper on the roof opening as it too will eventually catch lint. I would leave the line open in the same manner as the waste vents.

You may consider attaching a sweep 90 elbow on the end to afford protection from rain while not substantially reducing the airflow

[imeduc]

Out of the box here. But it sounds like you dont have an indoor screen that all the dryers have on them. yes some lint will come through the pipe but not that much. id check into that for sure.
What did you replace all of the B vent pipe for a gas burner?

ED

My mistakes dont define me they inform me.