is venting your dryer to the house O.K in winter?

[barry]

Exactly. It happens that's what I do in colder months when weather makes drying outdoors difficult. (Clothes still spend some time outdoors for the "fresh-air treatment.) Sadly, I don't live on a farm.

Putting the partly-dry clothes near the woodstove overnight finishes the job nicely, not to mention the humidification. No need to hang them, just pile them very loosely in baskets. Great air-freshener, too.

My electric dryer collects dust, on the outside. (And wastes space, but not energy.)

J

[Stretch]

Pop (& Nick)

International Mechanical Code:

Section 913.2 Exhaust Required. Clothes dryers shall be exhausted in accordance with Section 504.

Section 504.4 Exhaust installation. Dryer exhaust ducts for clothes dryers shall terminate on the outside of the building and shall be equiped with a backdraft damper...... Clothes dryer exhaust ducts shall not be connected to a vent connector, vent or chimney.

See also sections 504.5, 504.6, 504.61, 504.62, 504.7.

[Amun]

While there are dozens of posted replies pro and con, the only way you will ever be able to know for sure is to do it. I pretty much guarantee that in one year you will never do it again.

Especially if YOU are the one who cleans the house. That lint gets EVERYWHERE, and you will spend far more in energy costs running the vacuum cleaner 10 times as much as you did before.

AMUN

[Pop]

Hmm, that was interesting to see and I was ready to apologize, but something looked awfully familiar there. On top of that, being "international" I couldn't find anything in my quick research that would show it to be applicable to anything but commercial construction regs and nothing "national" that seemed to call for it other than a couple of city codes and their construction codes. So, I'm doubting that anything makes it applicable as a coded national requirement like NEC or NFPA etc.. Remember, the context here is the homeowner and what he can/can't do per applicable codes. This is exactly why I often tell people to check with their local code enforcement offices because there can be a lot of surprises.

A quick search showed that what I was right, there was something familiar about it. It's the same place that said, among other things:

"a) Attic furnaces and crawlspace furnaces are not permitted. " but, what's missing there is the fact that they ARE permitted, just under a different section and with caveats. But, this isn't the point here; the next one is:

"d) All dryer vents shall be metal or metal flex. Non-metallic vents for dryers are not permitted. See Section 504.6 and Amendment to 504.6 " Soo, the flexible, nylon-wire-ribbed parts sold in stores with UL and CSA ratings, even ETL probably, and EC, aren't allowable? I respectfully submit that they ARE permitted, just NOT for the commercial construction company doing the original install. Local codes will determine whether they are acceptable or not.

And then:

"All ductwork shall be a closed system and in compliance with the International Mechanical Code Section 603. Use of a stud space or joist space for a supply or plenum return is not permitted. Gypsum ducts are not permitted. Delete Sections 603.5 and

603.5.1. "

Well, I can show you several "Fuel Fired Appliances See Section 303 for approved and prohibited locations. a) Section 303.3 Prohibited locations Fuel-fired appliances shall not be located in, or obtain combustion air from, any of the following rooms or spaces.

1. Sleeping rooms
2. Bathrooms
3. Toilet rooms
4. Storage closets
5. Surgical rooms "

That's blatantly untrue and there HAS to be a section of exceptions or dependencies somewhere even for an international code. Fuel fired appliances are used in hotel rooms (sleeping rooms) and in my own home, which has now been inspected twice, once before we moved in and three years ago for acquiring a boarding licence to be a foster child home, and the ONLY thing either inspection ever found was too many things plugged into a power strip because its location appeared close to "permanent". It appeared as an "exception" and not a "violation". Oops! Sorry, I lied; they did find a violation - my garage wood stove (a huge one) wasn't considered grandfathered anymore and I had to pull it out. The previous owner here was a fireman and I guess he knew his way around the codes; he built, installed and inspected it . I didn't get that courtesy. Oh, they also considered it an "incinerator", not a wood stove, which made the "rules" a little different. The inspector wouldn't budge on that one. All I had to do tough was take the stovepipe off it and cover the chimney hole - then he passed me. Took about 15 minutes.

Anyway, I guess I should have said "applicable" code to the OPs situation, but I thought that was understood. Guess not.

Not really trying to be a PIA by the way - I just don't care for misperceptions.

Pop

[Bill]

Well if venting the dryer indoors, how much would it raise the indoor relative humidity? Only from 40% to 60%? I should think it would be more than that...

[Chris Lewis]

According to Jeff Wisnia :

I've been doing some research on this, and it appears that the technology just seems to have not produced something economically viable yet for residential class dryers. For multiple commercial dryers (ie: laundramats) certainly, but not a single relatively little used unit.

Coping with the lint is perhaps the major factor, otherwise, standard heat recovery ventilators (ie: those in R2000 homes are typically $500-$900) would be common already for this purpose.

The cheapest heat reclamation units I've seen suitable for dryers are on the order of $3K at a bare minimum, and routine service schedules (lint cleanout etc.) is apparently important. Significant effectiveness and a reasonably short repayment period in a commercial setting (especially when you share them amongst several units), but not useful in a residence.

[Edwin Pawlowski]

Based on what? The depends on the number of loads of laundry, wetness of hte laundry, size of hte house, etc. No one can give an accurate number as it differs from household to household.

[modervador]

You're telling me I can obtain a residential clothes dryer from Sears that is configured by the manufacturer (or with a factory-made accessory) to vent the gas exhaust separately from the "other" exhaust?

I want one. Model number please. All I could find was dryers which allowed a choice of where to run the single exhaust pipe (back, side, bottom).

[modervador]

I can't name the the particular number myself, but I believe there is a section that specifies that manufacturer's installation requirements must be followed. I've yet to see a residential gas dryer that did not require venting to the outdoors per the manufacturer's installation manual.

[James]

I would be a good idea to vent indoor if you get nose bleeds as I do in winter. Really low RH in my house during heating season.

[udarrell]

That's a soft water rinse. :-)

- udarrell

[nicksanspam]

1 load.

12 pounds of water.

A 2400 ft^2 average US house with 0.7 ACH, dried in H hours, with a 0.0025 outdoor humidity ratio.

Nick

[nicksanspam]

Wow. Can we install the damper backwards, after an open T in the house?

And if the guy who dries his clothes by the woodstove loosely stacked in laundry baskets were to bring his electric dryer back out of the rain into the house and put it near the woodstove and stack the clothes loosely inside, with no power applied, would he have to comply with section 504.4?

What if he turned on the tumbler motor without the electric heating elements?

Or put his clothes in a closet with a $12 heater and a humidistat?

Do the International Mechanical Code police often visit houses?

Are they something like The Spanish Inquisition?

Nick

[nicksanspam]

This reminds me of the National Mechanical Code, which is said to prohibit circulating conditioned air at more than 120 F in wooden stud spaces. I presume the excuse was the danger of fire, and the code committee creatures who wrote this sell fireproof materials.

A few of the few dozen wood solar attics in Soldiers Grove WI were lined with drywall after the state declared them "plenums," until pharmacist Don Stebbins refused to do so, saying the theoretical graph they were using for the time it takes wood to catch fire was in degrees C vs F, and the time scale was log vs linear. At this point the state creatures cravenly slunk away without reimbusing the injured parties. There have been no fires in 27 years.

Good thing the code creatures didn't see that part :-)

Nick

[nicksanspam]

10 WO=.0025'outdoor humidity ratio (Phila in January) 20 TR=70'room temp (F) 30 CFM=.7*2400*8/60'airflow through house (cfm) 40 W=12'pounds of water per load 50 FOR H=2 TO 12 STEP 2'drying time (hours) 60 P=W/H'water vapor supply rate (lb/h) 70 WI=WO+P/(60*CFM*.075)'indoor humidity ratio 80 PA=29.921/(1+.62198/WI)'vapor pressure of room air ("Hg) 90 PS=EXP(17.863-9621/(460+TR))'vapor pressure at Tr and 100% RH ("Hg) 100 RH=100*PA/PS'relative humidity in house (%) 110 PRINT H,RH 120 NEXT H

Time (H) RH (%)

2 53.60285 4 34.89333 6 28.61733 8 25.47186 10 23.58219 12 22.32141

Nick

[Jeff Wisnia]

Sound similar to the thread here a while ago started by someone who was wondering how he could recover the waste heat from warm shower water on its way down the drain.

Even in my most parsimonious of moods I wouldn't expect you'd ever get a payback of capital costs from doing something like that in a home.

Do they even do things like that in places like high school gym shower rooms?

I do remember a friend who about 35 years ago had a city water cooled air conditioning system in his home. The condenser was cooled by water, not air. He had it plumbed so that he could route the discharge water to his garden hose when he wanted to, but I expect those times were few and far between and most of the time the water just went down the drain.

That was back when city water was ignorably cheap. I haven't recently heard of any home air conditioning systems using water for condenser cooling, do they still make them? (Don't bother telling me about setting up a lawn sprinkler to spray the condenser of an air cooled unit. Same general principle, but that's not what I was rambling about.)

Jeff

[Bucky]

I had a natural gas dryer and vented inside the home. We installed a box with a flap in it to direct the exhaust outdoors or indoors. The indoors hole had a fine lint filter (similar to a nylon stocking), there was no lint coming out. I don't think there are any significant byproducts of natural gas combustion. There certainly was no odors or anything. I mean, it should be the same as a natural gas stove/range, and those are obviously not vented.

[Goedjn]

It may produce too much water, smells from soap and/or softeners, dust, and uneven heat. Stick one of those diverters in, and if you don't like the effect it has, take it out again. It's not going to destroy anything in one day, except possibly the wallpaper in the laundry.

[DrLith]

Are you sure? I looked at a site that said the average dryer load evaporates out 5 pints of water (and a pint being a pound, the world 'round, that's be 5 lbs of water).

[Chris Lewis]

It's "similar", but the difference in scale should be pretty obvious.

A dryer runs at around 3000-4000 watts. That's about half of an electric furnace. Blowing that much outside will cost you something reasonably substantial per operating hour (up to $1/hour range in some cases). This is considerably more wasted heat than 20 minutes worth of warm water - which is considerably harder to "extract" to any useful degree anyway.

Probably not at $3K. However, if it were less than $500 it starts becoming attractive.

It will be interesting to see if the stuff I saw gets down to prices reasonable for residential systems and not be quite so physically large.

Sometimes, you want to conserve power simply because it's the right thing to do.

The $3K technology I saw seems relatively new (just one manufacturer), so it hasn't gotten a lot of penetration even at the commercial end yet, where payback period was indicated to be in the 6-12 month range.

Our high school gym didn't have a dryer ;-)

If you're interested, I think this is the manufacturer I found earlier:

One happy customer: the technology better)

There's a patent on a simpler (no moving parts) one, but I don't think it's in manufacture:

This is an interesting discussion:

(references the rototherm unit)