Venting Cloths Dryers in projects

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Author Message Richard HIrd (Unregistered Guest) Unregistered guest Posted on Friday, May 25, 2012 - 09:26 am:    Working on a large three story apartment building where it was suggested that there were special dryers (Over/Under type) that were designed for extended venting. Have recommendations for products from makers, but none say in there write ups they are specific for this application. Is there such a thing, or do you just go for the biggest HP? Marc C Chavez Senior Member Username: mchavez Post Number: 458 Registered: 07-2002 Posted on Friday, May 25, 2012 - 11:09 am:    I ran into this years ago and it was a real trial. If you have too many turns or too long a run even larger machines don't create enough cfm to kick the lint out. We installed a supplemental fan that sits along side the vent to help push (pull) the air. I believe the analogy went like this: Think slow moving water in the gutter and you spray faster moving water into the stream with the garden hose, this moves the existing water and all the new added water, faster down stream and thus allows the slower water behind to "rush" in to fill the void. and faster water (or air) can "carry" more material with it. I may have the fluid dynamics wrong - probably do - but I had a great mechanical engineer - and he HAD passed that class. Therefore we added the fan and an extra filter for any lint that might get into the supplemental fan. There was some discussion about pressure sensors and alarms but I frankly dont remember that bit and I don't believe we had to add any. Trusting maintanance to clean the lint from the vent is about equal to trusting your little brother with your favorite record album. AND the mechanical code has soem very specific things to say about this issue too... Hope this helps Richard Hird (Unregistered Guest) Unregistered guest Posted on Friday, May 25, 2012 - 09:49 pm:    Marc I did find the fans, thru a home inspector's web site no less. it makes sense to pull the air thru at the end, or points or turns along the way. If you can get power to them they are self actuating. Lint build up and cleaning are still an issue at the fans so you have to get to them. Do not think that a special dryer can do much, unless it is supercharged, and that means the ducts need to be designed. However my client still insists their is such an animal. Will let you know if he comes up with one. Paul Sweet (Unregistered Guest) Unregistered guest Posted on Tuesday, May 29, 2012 - 04:45 pm:    As far as I know the International Mechanical Code doesn't allow booster fans for dryer exhausts any more. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 478 Registered: 10-2007 Posted on Tuesday, May 29, 2012 - 05:47 pm:    Coordinate the location and size of the openings in the exterior wall to accomodate the duct with the structural engineer. In wood construction the openings might make it difficult to use rim joists as collectors. Richard Hird PE (Unregistered Guest) Unregistered guest Posted on Tuesday, May 29, 2012 - 08:51 pm:    Paul/Mark: Very much appreciate the comments! Will look into them. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1402 Registered: 03-2002 Posted on Thursday, May 31, 2012 - 12:06 pm:    What we ended up with was unvented driers. My first reaction was that this was going to spew humidity into the apartments. But I did some research and found that they condense the moisture out of the exhaust stream. They also turn out to be more energy efficient. Our project got axed in the economic crash so I was never able to go the full distance on it. Other projects I worked on did use a continuously-operating fan on the dryer exhaust stack. Don Harris CSI, CCS, CCCA, AIA Senior Member Username: don_harris Post Number: 261 Registered: 03-2003 Posted on Friday, June 01, 2012 - 01:56 pm:    We are looking into the vent-less dryers on a project. Mostly for units where the dryers are located toward the interior of the building. It looks like they may save some ganged venting costs. There is also a combo washer/dryer by LG. Like John says, they condense the moisture and release it into the washer drain. Major manufacturers that we are looking at are Bosch, LG, GE and ASKO.