Venting Clothes Dryer and DC Together?

[Tim Byars]

I bought an older home, and the dryer exhaust in the laundry room vents directly into the garage (cutting a hole to route it outside, either in the laundry room or garage, has been on my list of things to do...I've temporarily rigged up a lint bucket where it comes out in the garage).

Meanwhile, I'm also looking at setting up some genuine dust control for my growing shop, which is also in the garage.

Is there any reason why I wouldn't vent everything outside together? Bring the ducts for both the DC and dryer together at the wall exit? It certainly seems like it would work, but I wonder whether there's anything I'm overlooking.

[Phil Thien]

The only thing I can think of is that the dust from the DC could get into the dryer, and that the gases/moisture from the dryer could get into the shop via the DC.

[Jamie Buxton]

I'm pretty sure that some of your sawdust will blow into the dryer. On my DC system, I have a stub piece of duct. It doesn't go anywhere, and the end is sealed. It is Y'd into the main line. The main flow of dust goes through the other branch of the Y. Dust has to reverse direction and go uphill to get into the stub. Despite that, the stub fills up with dust.

Maybe you could build a spring-loaded damper. It would normally connect the dryer to the exit. When the DC blows, its air pressure would push the damper to the other position. In that position, the damper blocks off the dryer duct, and lets the DC exhaust go outside.

Maybe another way to do the same thing would be to use two standard blast gates -- either manual ones or remotely-operated ones. The gates would allow either the DC to flow or the dryer to flow, but not both simultaneously.

[Ken Fitzgerald]

Tim...The DC will move air with greater pressure and volume. I'd be concerned about sawdust ending up in the dryer and or the vent. In my opinion, something like this may be doable but design it for worst case scenario. If something malfunctioned you wouldn't want the sawdust being blown into the dryer and dryer vent.

For safety I wouldn't do it but I'm pretty conservative when it comes to safety.

[Tim Byars]

Reading these posts and thinking it through, it's hard to ignore the fact that dedicated functions would just be so much "tighter".

And, my version of conservative was to try to make only one hole in the house, but I think I'm persuaded that Ken's version of caution makes more sense.

Thanks all.

[David Freed]

Tim...The DC will move air with greater pressure and volume. I'd be concerned about sawdust ending up in the dryer and or the vent. In my opinion, something like this may be doable but design it for worst case scenario. If something malfunctioned you wouldn't want the sawdust being blown into the dryer and dryer vent.

I agree. Dust in the dryer wouldn't be good, but if you dusted a freshly washed load of your wifes clothes, your next project might be a doghouse.

[Rob Russell]

Another issue is that the dryer exhaust has moisture in it. I'd think that would tend to make dust stick to the piping, which wouldn't be good.

[Jim Becker]

In addition to all the other objections, there is the issue that your dust collection system is going to have a larger vent than your dryer. I would not combine them even if they were the same size, however. And you DO want to get the dryer vent going outside. Exhausting into a garage can damage the home...I know...the previous owners had the dryer venting into the basement and it caused a lot of damage and rot to the structure.

[Robert Payne]

Clothes dryers remove pounds of water and convey the vapor at much lower flow rates than a DC system. Any time the dryer vent has to routed any distance, the temperature drops and there is a strong chance for the vapor to condense, especially if it is routed through unconditioned space. It should be hard ducted and pitched down (1/4" per foot) so any condensate will drain toward the outlet. I agree with others that these two should never be combined.

[Wayne Cannon]

Air vented outside from your shop's dust collector must/will be replaced from somewhere. If your garage also contains any combustion-based appliances, such as hot water heater or gas/oil furnace, the air will likely be sucked through the flues and combustion chambers of the appliances, creating a carbon monoxide hazard in your garage/shop! In other words, be careful about sucking air out of your garage, regardless of where you send it.

I would definitely vent the moist output from the dryer ourdoors, i.e., anywhere other than my shop and its cast iron.

Dust collectors move a LOT of air, so any heat or cooling in your garage/shop (even if only indirectly heated from a shared wall or ceiling with the house) would be quickly lost if vented outdoors -- replaced by outdoor air -- as opposed to returning the filtered warm/cool air back into the shop.

[Pat Germain]

FYI, when installing the new dryer vent, it's a good idea to use rigid vent pipe, rather than the flexible ducting, wherever possible. This would also be a very good time to give your dryer a thorough de-linting. You can buy dryer cleaning kits for a shop vac. They have nifty attachments designed to get inside the dryer for removing all the lint. And boy, do those things get full of lint!

Not only will de-linting result in the dryer working better, all that lint can be a fire hazard. Reducing fire hazards is why using rigid ducting is better than flexible.

[Tim Byars]

I would definitely vent the moist output from the dryer ourdoors, i.e., anywhere other than my shop and its cast iron.

Honestly it isn't much of a moisture issue for me here on the dessicated plains - I don't think I'd mind if the dryer raised the humidity in there around 50%, because then it would reach zero (rimshot, please...)
But seriously folks, that's one reason I've dragged my feet on moving the vent outside.

So, air quality is the huge issue, especially spending so much time out there now.

Also, I have read about the air replacement issue just trying to get educated about dust collection in general - one peculiarity of my situation is that my garage is not at all tight. It's drafty, there's daylight around the garage doors, etc. There's also a single vent from the HVAC in there...not at all enough for real climate control in a drafty oversize garage, but makes it slightly more comfortable and supplies a little ventilation. I wonder if all that would handle replacing the air with a modest DC system? (No water heaters out there, and no standing pilot on the new-ish furnace.)

[Tim Byars]

FYI, when installing the new dryer vent, it's a good idea to use rigid vent pipe, rather than the flexible ducting, wherever possible. This would also be a very good time to give your dryer a thorough de-linting. You can buy dryer cleaning kits for a shop vac. They have nifty attachments designed to get inside the dryer for removing all the lint. And boy, do those things get full of lint!

Not only will de-linting result in the dryer working better, all that lint can be a fire hazard. Reducing fire hazards is why using rigid ducting is better than flexible.

Oddly enough, the fire hazard issue is one that might be more comfortable the way it is now, even venting into the garage. It's about a 1-foot, straight and rigid run right now, making things like duct clogging and condensation pretty much non-existent...it's the easiest thing in the world to clean. (And I'm a compulsive de-linter...the statistics on dryer fires are really frightening.)

[Leo Zick]

Oddly enough, the fire hazard issue is one that might be more comfortable the way it is now, even venting into the garage. It's about a 1-foot, straight and rigid run right now, making things like duct clogging and condensation pretty much non-existent...it's the easiest thing in the world to clean. (And I'm a compulsive de-linter...the statistics on dryer fires are really frightening.)

other than UMC, i dont think there are any codes that dictate dryer vent install and safety. strange especially with the risk (as you point out, around 14k deaths/yr due to lint).

common sense should prevail. at one foot and with rigid pipe, im sure you are fine.

Consider a 45deg elbow tying the pipes together, so at least airflow is directed the right way.
a few days of cutting will obviously be your answer..

[Jay Yoder]

since we are discussing dryer vents and the like, let me ask how u would set this up. my current setup is 4" ridgid pipe. it is in my basement and has to exhaust thru the sideboard right above the concrete block. i have about 10' straight. I added a garage bay to the outside and now it vents into new bay. (I know poor planning). Approximately how many elbows and such can i have before i need to get a dryer vent booster fan. Has anyone installed one of these? i think i have about 12' w/ some elbows currently. Maybe that length is why it takes clothes so long to dry...any help would be appreciated...