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Thread: Dryer venting options

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  • Dryer venting options

    I’m working on a project in a ca. 1905 3 story home in which the architect has placed a 2nd floor laundry (stackable units) in a closet where the position of the dryer vent outlet is non-negotiable (I may only have 4 or 5″ of flexibility on its wall inlet position). Normally, we all go either up or down with the duct and horizontally out the nearest sidewall. Without going into detail, there are features in the house that make going out a sidewall impossible. So, my 2 choices are:

    1. Install recessed dryer box. Go up vertically 5 feet. Turn 90 degrees. Go horizontally 6 feet. Turn up 45 degrees and go 1 foot to a roof type vent outlet that would be right outside a 3rd floor window to allow for lint removal.

    2. Install recessed dryer box. Go up vertically 5 feet. Turn 90 degrees. Go horizontally 7 feet. Turn downward into a soffit vent that will be located approximately 22 ft off the ground.

    My main concerns are maintenance (lint buildup) and the potential for condensation, as our winters in Cincinnati can get rather cold. Any advice on what roof or soffit vents you guys like to use for dryers? Also, which option do you think is best, 1 or 2? I’ve always been able to go out a sidewall, so this is new territory for me. Thanks!

    I would go with the first one because the 2nd one goes up and down and could create a water trap. If you have exposed ductwork for the dryer in the attic you should insulate it. It’s not code in Ct but should be. Sounds like either one is within code so should be fine

    There’s also the option of getting one of those new dehumidifier dryers that don’t need a vent. With energy costs trending the way they are, it’s looking like a great choice.
    http://www.heatpumpdryers.com/

    A friend of mine have Miele condensing dryer in her old apartment, been out in Europe for years, apparently pretty mature technology.

    You can also install a booster fan with a secondary lint trap, increasing air pressure will make lint less likely to settle in vent pipes. It’s very commonly installed in newer high rise condos with low profile vent duct buried in concrete.

    You might want to consider using an externally mounted dryer booster fan like this RVF4XL:

    Vacuum Technology:
    CRUD = Contamination Resulting in Undesirable Deposits.
    CRAPP = Contamination Resulting in Additional Partial Pressure.

    Change your vacuum pump oil now.

    Test. Testing, 1,2,3.

    Thanks for the replies thus far. I am mostly concerned with lint buildup and condensation at the outlet (sorry, should have stated it more clearly). That being the case, would you choose a roof vent (hood) or soffit type vent?

    Mike I think I may owe you a beer.

    That dryer may just solve a problem (actually 40 problems) dropped in my lap.

    Four things cause lint buildup:
    1. Wet lint.
    2. Obstacles in the airway.
    3. Cold vent caps.
    4. Elbows and length. This last item is beyond the scope of my comments.

    If the wet lint travels far enough before encountering obstacles, it has a much better chance of drying out and moving past the obstacles instead of sticking to them. But if the obstacles are cold, the moisture in the air will re-condense and the lint will stick.

    To prevent lint sticking,
    1. Use tape, not screws. Avoid over-crimping pipe.
    2. Insulate duct.
    3. When using a dryer vent booster, install the blower far from dryer. IIRC, 15 feet is the minimum. The best blowers are those whose impellers have little or no contact with the lint stream.
    See
    http://www.tjernlund.com/dryer_booster.htm
    http://www.tjernlund.com/Dryer-Venting-articles.htm
    4. Use a secondary lint filter at the dryer.
    5. Don’t use soffit vent caps with grilles. They load up quickly. There are flapped soffit vent caps that are similar to wall vent caps. They work better, but they load up as well. They have to be cleared by hand from time to time.

    So the answer to your question is, install the vent cap where you have easy access to it, and use the least obstructive vent cap you can find. All other things being equal, the roof vent sounds like the best option on your short list.

    Of the above listed recommendations, by far the most effective cheap device is the lint filter.

    Alternatively, another option that works well is a filtered indoor vent. (These are not recommended with gas dryers.) You can buy one or make one yourself.

    The simplest indoor vent is a sock. You can attach a knit sock with a rubber band to a pipe attached to the back of your dryer. Use a regular rubber band like the ones used in most offices for bundling envelopes and other goods. Don’t use some kind of industrial strength rubber band. (The sock needs to fall off easily when it loads up.) Keep the sock where you can see it at all times. The sock will load up with lint, so it needs to be replaced with a clean one from time to time.

    Two disadvantages to the indoor filter method:
    1. If not managed properly, can be a fire hazard. Might not pass code.
    2. Heats house in summer.

    Four disadvantages of more conventional methods:
    1. Out of sight, out of mind. Lack of maintenance leads to fire hazards. Passing code doesn’t necessarily make it safer.
    2. More expensive to buy and install.
    3. More complex. More difficult and expensive to maintain.
    4. Wastes heat in winter.

    While the indoor vent is often passed over in favor of more complex and expensive solutions, it’s often the best, simply because its maintenance requirements are in your face and it’s easier to maintain than the more complex methods.

    The difference between maintenance methods is like the difference between remembering to get gas and remembering to change the oil. One is more likely to get done without a reminder than the other.

    Last edited by Space Racer; 08-13-2013 at 04:53 PM .

    Vacuum Technology:
    CRUD = Contamination Resulting in Undesirable Deposits.
    CRAPP = Contamination Resulting in Additional Partial Pressure.

    Change your vacuum pump oil now.

    I’m working on a project in a ca. 1905 3 story home in which the architect has placed a 2nd floor laundry (stackable units) in a closet where the position of the dryer vent outlet is non-negotiable (I may only have 4 or 5" of flexibility on its wall inlet position). Normally, we all go either up or down with the duct and horizontally out the nearest sidewall. Without going into detail, there are features in the house that make going out a sidewall impossible. So, my 2 choices are: 1.

    Venting Dryer Inside

    I have a theory, and I’d love feedback.

    I’m going to take a 5-gallon bucket with a lid, and I’m going to make a hole in the lid large enough to fit a piece of pvc that’s about 2 feet long, and about 3″ in diameter (or whatever fits the dryer vent hose).

    I’m going to put some holes within 1″ of the end of the pvc all around it. I’m going to fit the pvc through the hole of the tightly fitting lid, then submerge it into may 4- or 5″ of water.

    Then I’m hooking the vent from the dryer to the top of the pvc.

    The theory is that the steam should push into the water and cool, while the air should bubble out from the bottom of the pvc into the bucket. Some small holes in the lid of the bucket should allow the warmer air to escape ambiently, and I would hope that the humidity is reduced significantly by the water in the bucket. I figure that by the time the water warms to the point of equilibrium, the clothes should be about dry, and there should be little worry of re-steaming the area with the bucket water.

    But I just don’t know yet.

    Consider a heat exchanger. The air you get out of the dryer is very damp. The hose fell off my drier the other day and there was condensation running down the walls before I caught it.

    The other advantage of a heat exchanger is that you avoid blowing bits of lint around. Breathing in that sort of things isn’t good for your lungs’ health.

    For the heat exchanger, I suggest you ask the Google Machine for design advice.

    Be careful about back pressure. Dryers don’t have big enough fans to push the air through much water. Shame because that would deal with the humidity and clean the leftover lint.

    “You must be the change you want to see in the world.” “First they ignore you, then they laugh at you, then they fight you, then you win.” –Mahatma Gandhi
    “Preach the Gospel always, and if necessary, use words.” –Francis of Assisi.
    “Family farms work when the whole family works the farm.” — Adam Klaus

    Really good points, folks. Thank you.

    I would like to see about finding a metal, 5-gallon bucket instead. Maybe that would assist with the heat transfer better, thus allowing the water to continue to stay cooler on the basement floor and remove the steam. I’m hoping the warmer air bubbles out of the water and escapes the bucket through either vent holes in the top, or through an exhaust line.

    I’ll have to play with the water depth to compensate for the dryer’s air pressure. Burning it out would obviously be counterproductive.

    One thing I find interesting about these forums is the often times complicated solutions to some problem (real or perceived). This violates one of the basic rules of design . the most elegant solution to a problem is usually the simplest.

    Realize your potential by simplifying your life.
    “Learn how to see. Realize that everything connects to everything else.”

    Leonardo Da Vinci

    we have experimented with something similar to this, but with an off the shelf product.

    we used something similar to this:

    if you google: indoor dryer lint trap you will find similar products.

    we did find that is adds a ton of humidity to the house. so much so, that we set a fan on top of the dryer to help move the air out of the laundry room and throughout the rest of the house. we live in a desert, so added humidity isnt a bad thing, especially in the [dry] winter, which is the only time we use this (solar dryer 75% of the year)
    we did notice a lot more lint in the laundry room also. likely because the contraption above doesnt catch it all.

    edit: we only use this device in the winter when it is below

    35* as the clothes seem to freeze on our clothesline then

    http://www.cloud9farms.com/ – Southern Colorado – Zone 5 (-19*f) – 5300ft elevation – 12in rainfall plus irrigation rights
    Dairy cows, “hair” sheep, Kune Kune pigs, chickens, guineas and turkeys

    Clothes lines ! another simple solution, probably the best, In many Parts of the Country people have to fight for the right to hang their clothes on the line ! This is not a joke !
    there is no punchline ! In lots of places with shared services, a homeowners committee tells you what you can and can’t do !

    Including the right to Dry ! BIG AL !

    Success has a Thousand Fathers , Failure is an Orphan

    LOOK AT THE ” SIMILAR THREADS ” BELOW !

    Tom Gauthier wrote: One thing I find interesting about these forums is the often times complicated solutions to some problem (real or perceived). This violates one of the basic rules of design . the most elegant solution to a problem is usually the simplest.

    Sometimes the simplest solution is simple because it requires labor. I’m personally very short on time these days and drying laundry outside would be a challenge.

    Also, if you’re paying to heat your living space anyhow, it doesn’t hurt to dry some clothes first.

    Keeping with the simplicity of things, there’s a very simple reason that I’m looking to reroute my dryer’s venting inside:

    In the winter, it seems logical to use the heat from the dryer to help warm the house rather than the outside. Hanging clothes out makes them too cold to don.

    i think a lot of it will depends on local conditions.

    in the winter, we have low enough humidity and brisk enough winds, that clothes dry on the line, so long as they dont freeze.

    35* and above seems fine to hang clothes here.
    i can imagine in the midwest or northeast, you may get frozen clothes if they are left outside with the humidity there.

    we have also seen people who hang clothes inside, along south facing windows during the winter. less power usage, but you still get the humidity inside. helps if you have a wood stove going also.

    we thought “if im gonna run the dryer [in the winter] the last thing i want to do is dump that heat outside”

    http://www.cloud9farms.com/ – Southern Colorado – Zone 5 (-19*f) – 5300ft elevation – 12in rainfall plus irrigation rights
    Dairy cows, “hair” sheep, Kune Kune pigs, chickens, guineas and turkeys

    We’re in NH. The winters are crazy humid and heavy. No outdoor clothes drying here during the cold season.

    Our basement is also subject to mold due to the humidity. The Rocket Stove is helping with that, and now I have the heat exchange on the dryer, and it’s working better than I expected. The cold water in the bucket is handling a good 95% of the humidity from the steam. I’m psyched.

    Jeff, curious how you came to the conclusion that 95% of humidity is being handled? Call me a skeptic.

    This practice could compound the problems of humid air exfiltration through the envelope leading to hidden condensation (and m word) problems.

    Another way to add heat and humidity for better or worse is to not run bath vent fans during hot showers. I do this in my small house only after the furnace has had time to dry out the air.

    “If you want to save the environment, build a city worth living in.” – Wendell Berry

    The rocket heater in the basement is running full-burn throughout the day, which cuts the humidity considerably (my dehumidifier is only being emptied every 3 or 4 days now, rather than every day). The vapor from the dryer is hitting the cooler barrel and the cool water within, so the warm vapor condenses quite nicely. Little- to no vapor is visible coming from the small gaps around the lid of the barrel, and anything that does escape into the basement air is negligible, especially considering how much vapor was down there prior to the heater running and the dehumidifier running. A shower puts out way more steam than the attachment on the dryer does, so I’m pretty confident that the moister problem has actually been reduced, and the added warmth to the basement as my “thermal battery” is helpful.

    I have to add that I did not have the heat-exchange system set up on the dryer prior to the heater and dehumidifier running. The natural moisture in this basement is pretty intense. I was very worried about the dryer’s added moisture, but it is proving to be a non-issue.

    I’m going to take a 5-gallon bucket with a lid, and I’m going to make a hole in the lid large enough to fit a piece of pvc that’s about 2 feet long, and about 3 in diameter (or whatever fits the dryer vent hose). I figure that by the time the water warms to the point of equilibrium, the clothes should be about dry, and there should be little worry of re-steaming the area with the bucket water.