Do any of you vent your dryer through the roof? Does it work OK for you? What about snow on the roof, is it a pain for you to keep the vent clear? For a new laundry room install, I can do that with a straight run of about 11 feet up, or I can put an elbow in the attic and add about 18 feet to get to a side wall. Technically that is too long per code, but I am more concerned about proper functioning than code. So - which is better, through the roof, or too long? Greg
I am not sure what the vents were for, but I was in a larger city last year and there was a new apartment complex going up, they had many vents up through the top like an upright vent, but it had an upside down horseshoe. We both commented how simple and effective.
I'd be concerned with the lint building up if you went to the roof. The dryer isn't putting out high pressure to move it that far vertically. Every time it shuts off I believe you would have small amounts settling back down to the lowest point which I assume would be right at the outlet on the dryer itself. You could have a pretty substantial buildup in short order.
More of condensation factor particularly when it gets cooler out. then combine that with any lint and it gets like cement. shortest run possible out the side wall if possible. In either of your statements above you will need to make allowances for condensation collection and possible a drain line for same.
Greg, I had the same dilemma went I built this my last house. I decided to go thru the wall for the reasons others have stated. I did add a booster fan. Like this: http://shop.tjernlund.com/collections/frontpage/products/lb1 It was a little bit of money but cheap insurance if it prevents lint buildup and a fire. Our old neighbors house had a fire because of lint build up. I also add cleaning the dryer vent at the exhaust point to my list of things to do twice a year (when time changes usually) like checking the smoke detectors. Not as easy a decision as one might think. Good luck.
Not really answering your question, but have you considered a ventless dryer? Large capacity ventless heat pump clothes dryers have been available and in use in Europe for years, most notably by Bosch. Whirlpool has made a model available in the U.S. earlier this year. Cons: More expensive to purchase Generally take longer to dry the clothes More complicated mechanically Pros: Use about half the energy No hole in your house envelope No venting of your conditioned house air to the outside Can be used in any space https://www2.buildinggreen.com/article/heat-pump-clothes-dryers-finally-reach-us
The vertical rise is only about 2 feet more if I go out the roof than if I go out the side, so I am really tempted to go through the roof. But, as Minnesota Marty states, it is not as easy of a decision as it may seem. I will read a bit more about the boosters. DaveGunter thanks for the tip on the ventless dryer. I might do that, i need to look into it a bit more. We have a Bosch washer that my wife loves, and currently we don't have a dryer, s that might be the way to go. Greg
If you decide to go via the roof put a clean-out "T" behind the dryer so the lint has someplace to fall. Also insulate the pipe where it goes through the unheated space. You might want to go to one of the fire wood stove sites to see how they set up flues, they serve about the same purpose. I have a 4" bathroom vent that goes straight up. It works fine except during extremely cold spells. Before the sun hits it frost builds up in the section above the roof and restricts the flow. Dryer output, unless you are using the "fresh air" setting, should be warm enough to prevent this. KaptJaq EDIT: Be sure to have some type of spring loaded flaps on the cap at the top to prevent cold air from spilling down the pipe.
KaptJaq, All warm air venting thru unconditioned space should be insulated to an R-8 insulated ducting. All the Big Boxes sell insulated flex pipe. Sometimes I like running insulated flex pipe even in conditioned space, just for sound. I totally agree the the "T" behind the dryer as a lint trap. But, the key is remembering to clean it out. Regarding a bath vent that goes straight up I would urge you to consider adding more flex and putting in a "P" trap as sorts. Journal of Light Construction website has articles on correctly installing flex vent pipe. Running flex or rigid vent pipe straight up is a common installation error some HVAC guys make. DaveGunter, Interesting idea. I will need to do some more research on the ventless dryers. My concern, off the top of my head, is make up air for the gas. No worries about electric obviously. Greg, Bosch appliances are "top shelf" sometimes they get bad reviews by tradespeople installing them because they do require you to install THEIR WAY. And when you do their stuff seems to work just fine.
