Venting a dryer not on an exterior wall
joenorm
| Posted in General Questions on
Hello,
While I would have much preferred the dryer to be located on an exterior wall for easy venting, the new design I am building did not turn out this way and the Washer/Dryer are basically in the middle of the house.
Its not a large footprint so no direction is a very long run through the crawl space.
Vented crawl. My question is what is the proper way to vent the dryer.
I am assuming i’d want to stay in the insulated floor joist space to avoid a condensing pipe in the cooler crawl space.
Should I use hard line pipe for this?
Thanks
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Replies
Have you considered having a non vented crawl? If there is enough room to get in there, that would be a huge improvement. Hard line is always better, but if it is vented, not sure how much difference condensation is going to make since they are already pretty humid when they are vented, and it won't drip down on insulation, just dirt, that is already wet and it won't drip up into the dryer.
4" hard pipe is preferred. We generally run rigid pipe with the longest continuous runs as possible ie - a single 10' piece rather than five 2' pieces. Tape or mastic the seams to avoid screws. We generally sleeve the rigid pipe with R8 flex. Try to avoid condensation, wet lint is very hard to clean
Hey Joe,
I would imagine that you need to stay in the joist space anyway, to get the duct to exit the building through the rim. Where is your project located?
Rigid pipes do generally perform better than flex or corrugated ducting. Keep the basics in mind: keep turns to a minimum, tape seams, pitch the pipe so any condensation in the pipe drains, etc.
If you don't have a dryer yet, you could consider a condensing dryer, which doesn't need to be vented and which may be more efficient than a conventional dryer:
https://www.greenbuildingadvisor.com/article/energy-saving-clothes-dryers-hit-u-s-markets
https://www.finehomebuilding.com/2018/01/09/next-dryer-ventless
I haven't used these, but in theory these or something similar should be help for any turns.
https://www.amazon.com/Inovte-Degree-Overall-Length-Dryer-Ell/dp/B005FHXK2I
I believe Mike Guertin used those in the house he built with Fine Homebuilding...
Yes he did: https://www.finehomebuilding.com/2016/11/08/clothes-dryer-exhaust-vent
Joe,
Consider heat pump ventless options as well (to piggy-back on Brian's point). I love my Miele ventless HP washer/dryer combo. It is small but is more than enough for my wife and I. The dryer uses very, very little electricity.
Until simple, air tight dampers hit the US market, I'll always have a ventless dryer.
Rick,
These seem to fit that description.
https://www.amazon.ca/LAMBRO-LAO289W-4-Inch-Dryer-Vent/dp/B005EGQTU0/ref=asc_df_B005EGQTU0/?tag=googleshopc0c-20&linkCode=df0&hvadid=292953940978&hvpos=1o1&hvnetw=g&hvrand=15614345590517800395&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001623&hvtargid=pla-431518368676&psc=1
I have a similar model (different vendor on my house- they work and seal pretty well with periodic lint-cleaning (in my case 2-4x per year.)
This short DIY installation video shows how they work, starting at about the 1:15 mark.
https://www.youtube.com/watch?v=1Vzeyyh3I_Q
Codes and manufacturer's specs typically limit the maximum length of the vent pipe to 35', and that includes the "equivalent feet" of every ell along the path. Definitely use hard-pipe for both the straight runs and turns, and seal every joint (including the slip joints on any segmented ells) with duct mastic &/or HVAC tape, and limit the flex connections to the minimum necessary for hooking up the dryer with enough wiggle room for service.
See section M1502 of the IRC- in particular M1502.4.5:
https://codes.iccsafe.org/content/IRC2015/chapter-15-exhaust-systems