Clothes dryers in conditioned envelope

FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
We have a natural gas dryer inside the conditioned envelope of our house. That crazy thing runs 10 - 12 hours every weekend and several more throughout the week while the wife does the laundry. Our climate is hot and humid full of gulf moisture. I know it puts a heck of a load inside our house latent and sensible heat wise which I have to pay the air conditioner to remove.

I am on a mission to reduce uneccesary KWh consumption and I know this creates a terrible inefficiency and operation cost.

I need some general input before I commit myself to a grave mistake. My thoughts:

1) Pull dryer inlet air from outside conditioned envelope. This involves sealing the plenum and all the intake louvres on the rear of the dryer, make an 8" opening at the rear of the dryer, and bring an 8" round insulated duct from a ventilated attic space which is still well over 100 deg F. The attic space is over the garage, and is "clean" with no insulation or other nasty particles.

2) Potential higher static pressure and cfm loss due to inlet duct design could be overcome by an inline dryer booster on the output of the dryer. A lack of airflow through the dryer would cause excessive short-cycling of the burner due to a temperature limit condition I'm sure.

3) Pulling the air from a 110-130 degree F space requires less btu's to dry clothes than pulling from a 78 degree F, I would assume. The burner should cycle less if the temperature inside the drum is supplemented by hot attic air?

Any thought on this, or seen anything like this in action?

Comments

  • Ralph DayRalph Day Solar Expert Posts: 892 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    FL Sun,
    Never thought of that for clothes drying, but I've seen the idea in a chicken barn...attic air (warmer than outside air) brought through a heat exchanger and discharged into the barn.

    The fewer elbows and turns both on inlet and outlet the better for efficiency. Good luck.

    If you keep track of equivilant loads dried the old way and the new way and see any differences everyone here would love to hear about it (and see the rigging.

    Ralph
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Clothes dryers in conditioned envelope

    You will need to filter the incoming air, fiberglass fibers don't mix well with clothes!

    The simple solution is move the dryer into the garage, that way the heat doesn't put an additional load on the AC
  • Ralph DayRalph Day Solar Expert Posts: 892 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    SG, as usual comes up with the most cost effective and simple solution. If you are the one doing the laundry of course. Me, I take it all to the basement, wash it, carry it all back upstairs to hang on an outside line. If your launder-er is willing to basket the wet stuff to the garage and back again, you're in luck.

    Ralph
  • mike95490mike95490 Solar Expert Posts: 8,470 ✭✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    So, what is the "hit" ? Using dry, conditioned air, as feedstock for the dryer, or having the dryer run longer (gas, drum & blower) to dry the clothes in 90% humidity? $

    I've heard of using hot attic air as feed for dryer. Gotta filter it though, as SG says. May need a booster fan to get air thru filter and all the extra duct. $$

    What about segerating the room it's in, or using a small stand-alone dehumidifier to dry the intake air, seperate from the house main AC? $$

    Put a coin slot on the dryer?

    Fresh air intake via heat exhanger (for laundry only) $$

    Sticky mess you have.
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  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    You will need to filter the incoming air, fiberglass fibers don't mix well with clothes!

    The simple solution is move the dryer into the garage, that way the heat doesn't put an additional load on the AC

    Howdy Guppy!

    This attic space has no fiberglass insulation, and is only over the garage. This attic is separated from the main house by a closed cell foam curtain wall, as the house construction is ICF and closed cell foam on the underdeck in the envelope. No nasty fibers here. Filtering the inlet air is a great idea.

    How I wish it could be so simple to move the dryer in the garage, but the resident "laundry engineer" would not have it, and there is not room for a dryer.:cry:
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    Ralph Day wrote: »
    SG, as usual comes up with the most cost effective and simple solution. If you are the one doing the laundry of course. Me, I take it all to the basement, wash it, carry it all back upstairs to hang on an outside line. If your launder-er is willing to basket the wet stuff to the garage and back again, you're in luck.

    Ralph

    That's a no go Ralph. SOL for me on the garage idea.
  • icarusicarus Solar Expert Posts: 5,355 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    I was going to suggest the garage, or draw air from the attic but that seems to be a dead hours.

    Not withstanding the humidity, things do dry in fresh air on a line. Clearly we make life style choices that come with cost(s).

    Tony
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    Mike - great points. My thoughts interleaved in bold.
    mike90045 wrote: »
    So, what is the "hit" ? Using dry, conditioned air, as feedstock for the dryer, or having the dryer run longer (gas, drum & blower) to dry the clothes in 90% humidity? $
    Interesting concept on the humidity. Summer design criteria for our area is an 80 deg F wet bulb temperature. Looking at a psychrometric chart, that is around 80% RH at 85 degrees dry bulb. That same air in a 115 deg F attic actually lowers the RH to right at 35%! This is because the air expands as it is heated, and the grains of moisture per lb of air is reduced because of it. This is why we call it 'relative' humidity since it's relative to the air temperature.

    I've heard of using hot attic air as feed for dryer. Gotta filter it though, as SG says. May need a booster fan to get air thru filter and all the extra duct. $$
    Filtering is a good idea. Booster fan may need to be installed as you said.

    What about segerating the room it's in, or using a small stand-alone dehumidifier to dry the intake air, seperate from the house main AC? $$
    I've thought about segregating the laundry room and treating it as non-conditioned. To do it right, this would intail insulating the laundry room walls and ceiling, and bringing in a passive outside make up duct. Since the structure is ICF and closed cell foam, correctly insulating it and installing an insulated exterior door from the house to the laundry does not work out to be a satisfactory approach.

    Put a coin slot on the dryer?
    Meaning go to the laundrymat?:cool::p

    Fresh air intake via heat exhanger (for laundry only) $$
    An ERV is a great idea, but I've tested numerous of those against our humid air. The passive enthalpic core just does not have the umph to remove enough of the latent load from outside air to be 100% effective. We have to really rely on mechanical refrigeration here to remove the moisture in our outside air.

    Sticky mess you have.

    It is a dilemma. Another trivial note, the most energy consumed regarding air conditioning is the removal of moisture. It takes less "work" to reduce the temperature 1 deg dry bulb than it does to reduce humidity 1 point. So the goal is to maintain strict moisture control inside the conditioned envelope when it come to energy conservation and HVAC in our southern, humid environment. This also includes bathroom and kitchen moisture control as well.
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    icarus wrote: »
    Not withstanding the humidity, things do dry in fresh air on a line. Clearly we make life style choices that come with cost(s).

    Tony

    Hi Tony

    Hanging the laundry would be my first choice. And you are right about lifestyle choices. If it was up to me and only my laundry, the clothesline would rule. I tell my wife to hang the laundry from the clothesline, and she'll have a different use for that line for sure!:p
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    I am sure it is, but the dryer is ducted outside right? Can you check that ducting to make sure it is clear and open? A blocked dryer exhaust will drastically increase drying times. If it is a longer run adding a booster on the exhaust will help as well as well. The more air you can move through the dryer the better, humid or not once it's warmed up 50F or so above intake temps will be pretty dry.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • DabblerDabbler Registered Users Posts: 22
    Re: Clothes dryers in conditioned envelope

    If I may, I have some input. If you haven't yet, you might try some "quick & dirty" way of ducting or blowing some of the attic air into the room and see what you think of the air quality. I have tried a simple version of what you suggested and abandoned it because of the air quality.

    My roof is a wooden structure, with cement tiles on top. I have no insulation (yet), so I didn't have the insulation concern either. I'm near Miami and the attic reaches 110-120 degrees in the Summer. I have a 2 foot square access from the attic to the garage where my dryer is located, so I put an attic fan in the access, and blew hot attic air into the garage in the late afternoon when the attic was hot, to do the drying then (and cool the attic).

    Sure enough, the garage would heat up to 100 degrees or more, so I didn't start any modifications to the dryer. I just ran it in place (it's output vented to the outside).

    What I found, though, was that the air in the garage had a distinct smell to it. Even though the roof is 12 years old, it was a wood-sap/chemical kind of smell, and after spending some time out there, my eyes would burn slightly and my nose and head get congested, similar to when I've done 3 or 4 day stints of too much woodworking and sanding. The smell was noticeable on the dried clothes. They smelled alot like the attic. ;)

    I don't know what it was. Seems like sap or wood additives in the attic would have out-gassed by now, maybe it was even dust and pollen which got in through the soffit vents over the years. I don't know, but it was bad enough to make the idea a "no go" without some kind of heat exchanger, which didn't seem like it would pay for itself any day soon.

    Maybe your attic will smell better than mine! ;)
  • icarusicarus Solar Expert Posts: 5,355 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    How about ducting from the condenser of the a/c/heat pump unit? Probably more trouble than it is worth,, but if you could time dryer use to a/c use you might have marginal ef gain from the a/c and to the dryer.

    One other possible idea would be to not use heat with the dryer and just use air, clearly you would have significantly longer run times, but if you were drawing air from an attic or a/c condenser you might see a sizable reduction in dryer cost.

    As for using the line, lead by example. Do you own laundry and hang it out. The to convince your wife,, figure out the net cost to dry each load of laundry. Lets just say for the sake of argument that it is $1 per load, ten loads a week would be $10, or $520/year. Tell here you will take her for a week end away at a fancy hotel with dinner if she agrees to hang out the laundry (weather permitting) for a year. Your net (family) cost will be the same, but I would rather have the week end rather than the electric bill!

    My wife is almost (not quite) the energy Nazi that I am. The reality is those of us that live cheaply do it out of a combination of necessity and choice. Every dollar NOT spent on something is a dollar less we have to earn, or a dollar that is available for some other purpose. (Let's see, $520 a year, I could buy another couple of hundred watts of Pv,, whoo-hoo!)

    Tony
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    Brock wrote: »
    I am sure it is, but the dryer is ducted outside right? Can you check that ducting to make sure it is clear and open? A blocked dryer exhaust will drastically increase drying times. If it is a longer run adding a booster on the exhaust will help as well as well. The more air you can move through the dryer the better, humid or not once it's warmed up 50F or so above intake temps will be pretty dry.

    The vent is ducted outside. But it is about 20 ft long and has several 90's in it that may impede airflow. I have to clean it like a gun barrel every so often as the dryer's design for lint filtration is poor. I am considering the booster fan.

    But that still will not solve the negative pressure issue. Still have to try to figure a way to draw all dryer air from outside the conditioned envelope without introducing it in the house.
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    Dabbler wrote: »
    What I found, though, was that the air in the garage had a distinct smell to it. Even though the roof is 12 years old, it was a wood-sap/chemical kind of smell, and after spending some time out there, my eyes would burn slightly and my nose and head get congested, similar to when I've done 3 or 4 day stints of too much woodworking and sanding. The smell was noticeable on the dried clothes. They smelled alot like the attic. ;)

    I don't know what it was. Seems like sap or wood additives in the attic would have out-gassed by now, maybe it was even dust and pollen which got in through the soffit vents over the years. I don't know, but it was bad enough to make the idea a "no go" without some kind of heat exchanger, which didn't seem like it would pay for itself any day soon.

    Maybe your attic will smell better than mine! ;)

    Dabbler, I have noticed attics do have an odor. That would not be a good thing to have clothes with that "fresh attic aroma". I'll make sure that doesn't happen.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Clothes dryers in conditioned envelope

    Our clothes dryer: 15' x 15' screened porch, two lines. Uses no electricity, gas, or chemicals and the clothes come out soft and fresh.
    Our washing machine: laundry tub. Infinitely variable on water level, wash times, cycles. Only trouble is that the agitator runs mainly on chocolate chip cookies ... :p
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope

    hmmm. i'll have what he's having and make it a dozen.;):D
  • FL SUNFL SUN Solar Expert Posts: 94 ✭✭✭✭
    Re: Clothes dryers in conditioned envelope
    Our clothes dryer: 15' x 15' screened porch, two lines. Uses no electricity, gas, or chemicals and the clothes come out soft and fresh.
    Our washing machine: laundry tub. Infinitely variable on water level, wash times, cycles. Only trouble is that the agitator runs mainly on chocolate chip cookies ... :p

    Now that's the life......Laundry tub, washboard, homemade lye soap made from the firepit, clothesline. Then go plow the field and harvest the veggies. Just enough daylight to hunt some game for the table.

    And I work work work, just to be able to buy the laundry detergent, pay for the electricity and gas to run it all, buy the food, make the house payment, insurance, whatever else. Half my paycheck goes to make someone else rich in taxes, etc.....The other half goes to interest on all the loans I'm trying to pay off....

    Would be an interesting thought to slow down, and work the land to make it work for me.

    Gotta hand it to you folks out in the wilderness. A few hundred watts of panels, battery storage, working off your own resources in the wild. Sure seems to beat the old hubbub of life us city folk have somehow convinced ourselves we have to have all these luxuries.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Clothes dryers in conditioned envelope

    We're not that different, you and I.
    Being Canadian, half my income goes to taxes. The rest goes to pay off the loans and try to survive. Kinda leaves you out in the wilderness struggling to get by ...

    The worst part is having to saddle a wild moose every time you want to go into town. :p
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Clothes dryers in conditioned envelope

    Well Ive been looking for a solution to drying our clothes on wet days and since Ive just built a 40ft x 35 ft covered porch around the east south west sides of the house with 11 foot high eves (basically to give us shade from the sun I remember when I was a lad (1970s) my parents had one of these

    Ive seen a six lat version which will be 10 ft long, for about 70$ so hopefully that will be fitted for the rainy days .

    Doesnt come with a plug fitted just a rope :p

    Also doesnt solve OPs problem but it does show how you look at solutions differently when living off grid making your own power from a former city dweller;)
  • System2System2 Posts: 6,290 admin
    Re: Clothes dryers in conditioned envelope

    A spin dryer is another tool you can use to get the clothes dry without having to use a lot of energy.

    your link has been eliminated as it was violating the rules, niel
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Clothes dryers in conditioned envelope

    I've just had the use of a commercial-grade Whirlpool washing machine. The clothes came out of it nearly dry; not dripping with water. This greatly reduced drying time, and thus saved energy. I suspect its better performance is due to superior spin cycle extracting more water to begin with. This improves cleaning too, as more of the dirty water is removed in the wash cycle, so less dirt remains for rinsing.
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