# Dryer Vent to Basement



## joecaption (Nov 30, 2011)

Those silly things should be against the law.
Basement is by far the most likely place to have moisture issues.
It should have been vented to the outside.
Most often it's ran out the the rim joist.
No heat lost involved.


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## Thunder Chicken (May 22, 2011)

Think of how much water is in a wet load of laundry - that is what is being dumped into the basement every time the dryer is used. That water doesn't magically disappear. Huge potential for moisture damage and mold.

Get this dryer vented through the wall. Installing a through-wall dryer vent isn't too hard but it needs to be done properly, like any wall penetration. Heat loss really isn't a problem.


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## gregzoll (Dec 25, 2006)

Dryers use less electricity then an electric stove does.


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## Thunder Chicken (May 22, 2011)

Remember that a dryer needs good ventilation in order to work properly, and not just on the hot discharge side. The dryer pulls in dry air, heats it, and then passes it through the tumbling clothes to cause evaporation to the air, which then should be vented _outside_. The dryer is pulling air from the interior of the house. If the house is really tight, the blower won't be able to move enough air and the dryer won't work well. 

If the dryer is near a window, the window should be cracked when the dryer is operating to allow free air flow though the dryer. Yes, this lets some cold air into the house, but this cold air will be pulled through the dryer and exhausted anyway. This is much more energy efficient than having it pull heated interior air out of the house. The volume of air going through the dryer during the cycle is probably enough to replace all the air in your house, so it's much better to draw this air mostly from the outdoors. When the dryer is done, close the window.


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## Tom738 (Jun 1, 2010)

gregzoll said:


> Dryers use less electricity then an electric stove does.


When she stopped using the dryer one season a decade or so back she cut her power bill by something like a quarter. (Granted, it was a year when she had to do a lot of laundry.) You also don't necessarily use an electric stove very much--the wood-burning stove and microwave both work nicely. Her biggest power sink right now is probably the big old electric hot water heater. Regardless, if you have lots of space, it's really easy to dry clothes on a clothesline in summer or drying rack in winter (and the clothes often dry better--fewer wrinkles if dried at all, and a better smell if dried outdoors), so she doesn't spend the extra money on the dryer unless she needs something quickly.

Electricity is so absurdly expensive in Ontario (unpredictable billing, mismanaged, paying back debt that an abusive incompetent monopoly accrued decades ago, with their billing so screwed up that any non-monopoly company in the world would not be able to stay in business with that kind of an operation--all combining to make power absurdly expensive for anyone not fairly wealthy to begin with, at least in the rural areas. It turns out that a lot of rural Ontario is very poor. And the published rates are pretty much useless for comparing prices, because of the way they change based on the kind of location, and they charge the customers different amounts for generation, transmission, and delivery.) It's not that the guys working for the Ontario Energy Board don't try, but they're working with a fundamentally broken system of administration below them. And then all the way down, the guys working the line are sometimes great, but are sometimes *******s who lie to homeowners about what they're going to do to get permission to do certain work or dumb kids who cut down two-hundred-year-old beautiful, healthy trees just for the fun of it.


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## Tom738 (Jun 1, 2010)

Thunder Chicken said:


> Remember that a dryer needs good ventilation in order to work properly, and not just on the hot discharge side. The dryer pulls in dry air, heats it, and then passes it through the tumbling clothes to cause evaporation to the air, which then should be vented _outside_. The dryer is pulling air from the interior of the house. If the house is really tight, the blower won't be able to move enough air and the dryer won't work well.
> 
> If the dryer is near a window, the window should be cracked when the dryer is operating to allow free air flow though the dryer. Yes, this lets some cold air into the house, but this cold air will be pulled through the dryer and exhausted anyway. This is much more energy efficient than having it pull heated interior air out of the house. The volume of air going through the dryer during the cycle is probably enough to replace all the air in your house, so it's much better to draw this air mostly from the outdoors. When the dryer is done, close the window.


This is a really interesting point. If accurate, it suggests dryers are designed wrong for cold climates and should really have their own air supply from outside.


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## Gary in WA (Mar 11, 2009)

gregzoll said:


> Dryers use less electricity then an electric stove does.


----------- maybe a gas dryer, Electric dryer- no; https://www.sparkenergy.com/en/blog/archive/appliance-electricity-usage-guide/

Annually per use including oven, both are still less; https://www.efficiencyvermont.com/f...frigerators/General-Info/Electric-Usage-Chart

Without the open window, cold air does constantly enter the dryer bottom through the ducting with a poor/non-sealing flapper at the exterior termination point when not in use. Certain vents are better than others per resistance, if you install one; http://www.dryerbox.com/ratings/dryerfittingschart.htm

Be sure to install it per local code; eg. *pp.23;*http://www.codecheck.com/cc/ccimages/PDFs/CC6th_Sample.pdf

The moisture will go to the coldest part (wall/ceiling) of the room or the ceiling near the bucket- rising with the warm air- depending on the basement air currents. Mildew (mold) could easily happen, look all around. We can help with the install...

Gary


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## Thunder Chicken (May 22, 2011)

Tom738 said:


> This is a really interesting point. If accurate, it suggests dryers are designed wrong for cold climates and should really have their own air supply from outside.


If you ever go to a laundromat, you'll see that the dryers are often set _through_ the wall just for this reason, to pull air directly from the outdoors through the dryer and out the exhaust. Otherwise, if you had 20 dryers each trying to pull 200 cfm, you wouldn't be able to pull the door open and your ears would pop from the negative pressure.

For occasional use, in a house that needs fresh air ventilation anyway, just cracking a nearby window will be fine.


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## Tom738 (Jun 1, 2010)

Thunder Chicken said:


> If you ever go to a laundromat, you'll see that the dryers are often set _through_ the wall just for this reason, to pull air directly from the outdoors through the dryer and out the exhaust. Otherwise, if you had 20 dryers each trying to pull 200 cfm, you wouldn't be able to pull the door open and your ears would pop from the negative pressure.
> 
> For occasional use, in a house that needs fresh air ventilation anyway, just cracking a nearby window will be fine.


Interesting. I will have to look at dryer design a little at some point.

If that figure is representative of an older dryer, 200 cfm from the bottom would be about the bottom 0.5 vertical feet of air per minute from a 400 square foot room (assuming no serious air movement in and out). So over half an hour, you would suck more than the entire warm air out of the room. Given a hundred degree difference between interior and exterior temperatures, at about 0.25 btu/degree(F)/cf, that is about 0.25 btu/degree/cf * 15.0 ft *400 sqft *100 degrees=150,000 btu of heat lost if the air is being pulled from the inside. Of course, it will actually be a bit different because (1) air sucked into the dryer won't be uniform and linear from the bottom (2) there will be some air exchange with other rooms in the home, (3) the btu/degree/cf figure is for pretty dry air, and (4) while the difference at thirty below may be 100 degrees, the difference will be less down at floor level. 

That sounds... hard to believe, because 150,000 btu is more heat by far than most homes are able to generate in an hour, and any room operating a dryer would get a *lot* colder very quickly.

Still, worth keeping in mind.


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## gregzoll (Dec 25, 2006)

Thunder Chicken said:


> If you ever go to a laundromat, you'll see that the dryers are often set _through_ the wall just for this reason, to pull air directly from the outdoors through the dryer and out the exhaust. Otherwise, if you had 20 dryers each trying to pull 200 cfm, you wouldn't be able to pull the door open and your ears would pop from the negative pressure.
> 
> For occasional use, in a house that needs fresh air ventilation anyway, just cracking a nearby window will be fine.


Actually they are placed within a false wall. Behind it is the back wall and the backs of the dryers.

They do it that way, so that they can still get to the back of them for cleaning and maintenance.

There is no other ventung in a laundry mat, other than the front door.


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## Thunder Chicken (May 22, 2011)

Tom738 said:


> Interesting. I will have to look at dryer design a little at some point.
> 
> If that figure is representative of an older dryer, 200 cfm from the bottom would be about the bottom 0.5 vertical feet of air per minute from a 400 square foot room (assuming no serious air movement in and out). So over half an hour, you would suck more than the entire warm air out of the room. Given a hundred degree difference between interior and exterior temperatures, at about 0.25 btu/degree(F)/cf, that is about 0.25 btu/degree/cf * 15.0 ft *400 sqft *100 degrees=150,000 btu of heat lost if the air is being pulled from the inside. Of course, it will actually be a bit different because (1) air sucked into the dryer won't be uniform and linear from the bottom (2) there will be some air exchange with other rooms in the home, (3) the btu/degree/cf figure is for pretty dry air, and (4) while the difference at thirty below may be 100 degrees, the difference will be less down at floor level.
> 
> ...


Your math isn't quite right*. The specific heat of air is 0.25 Btu/*lb-*F. 1 cubic foot of air is 0.0765 lbs. So you lose about 11,500 Btu per hour, which is something your heating system can manage. This costs you about 3.4 kWh in heat every time you run your dryer, not counting the electricity required to actually run the dryer. If you have a window next to your dryer and pull the air from the outside (mostly), you save some or all of that 3.4 kWh.

*I teach engineering thermodynamics in college.


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## beenthere (Oct 11, 2008)

Thunder Chicken said:


> Remember that a dryer needs good ventilation in order to work properly, and not just on the hot discharge side. The dryer pulls in dry air, heats it, and then passes it through the tumbling clothes to cause evaporation to the air, which then should be vented _outside_. The dryer is pulling air from the interior of the house. If the house is really tight, the blower won't be able to move enough air and the dryer won't work well.
> 
> If the dryer is near a window, the window should be cracked when the dryer is operating to allow free air flow though the dryer. Yes, this lets some cold air into the house, but this cold air will be pulled through the dryer and exhausted anyway. This is much more energy efficient than having it pull heated interior air out of the house. The volume of air going through the dryer during the cycle is probably enough to replace all the air in your house, so it's much better to draw this air mostly from the outdoors. When the dryer is done, close the window.


Cost about the same either way.


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## beenthere (Oct 11, 2008)

Thunder Chicken said:


> Your math isn't quite right*. The specific heat of air is 0.25 Btu/*lb-*F. 1 cubic foot of air is 0.0765 lbs. So you lose about 11,500 Btu per hour, which is something your heating system can manage. This costs you about 3.4 kWh in heat every time you run your dryer, not counting the electricity required to actually run the dryer. If you have a window next to your dryer and pull the air from the outside (mostly), you save some or all of that 3.4 kWh.
> 
> *I teach engineering thermodynamics in college.


With the current set up. No heat is lost from the home, since they are putting the heat into the basement. 

Opening a window when its -40°F outside is counter productive.


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## Thunder Chicken (May 22, 2011)

Except they would be dumping a lot of humid air into a cold basement. If they don't want condensation and mold, then they need to get that humid air out of the building. Given they need to get the humid air out, they should try to deliver outside air to the dryer so it isn't pulling warm air out of the house.


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## Daniel Holzman (Mar 10, 2009)

I use a different system. I have a conventional electric dryer in the basement. I have an air to air heat exchanger hot water heater (the GE Geospring model). This type of hot water heater will condense moisture out of the air, and convert the latent heat content of the water vapor into heat for the hot water. So I vent my dryer directly into the basement through a special vent designed for that purpose, with a sock over the duct to capture lint.

The hot water heater acts like a dehumidifier in the basement, so the exhausted moist air from the dryer is partially condensed in the winter, leaving a very nice, humidified basement. In the summer, much of the moisture in the air is condensed by the hot water heater, again leaving a dry basement.

This only works because the hot water heater is a heat exchanger model, but there are several companies that make them. I have been doing this for almost ten years without any problems. The hot water heater cost me about $1200 years ago, not sure what they go for now, but it is more efficient than a conventional electric water heater, and MA electric rates are about the highest in the country, so it makes sense in my case.


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## Thunder Chicken (May 22, 2011)

Daniel Holzman said:


> The hot water heater acts like a dehumidifier in the basement, so the exhausted moist air from the dryer is partially condensed in the winter, leaving a very nice, humidified basement. In the summer, much of the moisture in the air is condensed by the hot water heater, again leaving a dry basement.


This could be a great solution for the OP as it would let them actually use the heat from the dryer to help heat the house while removing any potential condensation and mold issues. Cool.

I should look into this.


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## mikegp (Jul 17, 2011)

joecaption said:


> No heat lost involved.


I would say every dryer vent loses heat. I have one of the fancier ones and it still loses heat. The vent duct is cold. I disconnected the duct the other day and cold air poured in. It wasn't even that cold out, probably mid 40's. I'm thinking about insulating the duct itself, but maybe the dryer will just become the cold spot.

I have one of these:


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## gregzoll (Dec 25, 2006)

mikegp if you are feeling cold air from outside. You need a different vent.


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## Tom738 (Jun 1, 2010)

Thunder Chicken said:


> Your math isn't quite right*. The specific heat of air is 0.25 Btu/*lb-*F. 1 cubic foot of air is 0.0765 lbs. So you lose about 11,500 Btu per hour, which is something your heating system can manage. This costs you about 3.4 kWh in heat every time you run your dryer, not counting the electricity required to actually run the dryer. If you have a window next to your dryer and pull the air from the outside (mostly), you save some or all of that 3.4 kWh.
> 
> *I teach engineering thermodynamics in college.


Okay, ONE order of magnitude...  

Thank you.


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## mikegp (Jul 17, 2011)

gregzoll said:


> mikegp if you are feeling cold air from outside. You need a different vent.


It's not airflow, it's just temp change.


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## beenthere (Oct 11, 2008)

Thunder Chicken said:


> Except they would be dumping a lot of humid air into a cold basement. If they don't want condensation and mold, then they need to get that humid air out of the building. Given they need to get the humid air out, they should try to deliver outside air to the dryer so it isn't pulling warm air out of the house.


Used only occasionally, won't be much moisture added to the basement.

You can recheck my result. It comes from Carrier's Psychrometric software.

But if he/she cracks the window open when its -30°F outside, and the drier is exhausting 200 CFM, and that 200 CFM is from that -30°F air. It would take 29,159 BTUs to heat the air up to 105°F(I think that is the average driers low temp setting) to dry the clothes. Which is more heat then they average electric clothes drier produces.

If they are going to use it daily, then it would need to be vented outside. Use only indoor air, and let the main heating system provide the extra heat needed.


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