Posts Tagged ‘Heat reclamation’

Efficiency & Bathroom Humidity

January 27, 2010

Reader Frank recently commented:

“Another strategy that I’ve found useful is the proper use of the bathroom vent fan. I know the cfm rating of it and after figuring the size of the room determined that the fan is capable of completely exhanging ALL the air in the room in under two minutes! Excess humidity is no good either; the windows throughout the house frost up noticeably more when the fan doesn’t get used and interior humidity is too high. Anyway~ fan stays off during shower operations and gets flipped on for 1-2 minutes right after, and that’s it. Most of the humidity goes out, most of the heat stays in.”

This reminded me that I’ve been meaning to to discuss bathroom vents.  To start with my conclusion: unless you use them as Frank does (i.e., most judiciously) I think they are a horrible idea in winter.  They are the equivalent of cutting a hole in the wall and blowing cold air in through it at somewhere between 50 and 200 cubic feet per minute.  Oh, I know– they don’t blow air in, they blow air out.   But that air is replaced with air from some other part of your house… which is replaced with air straight from outdoors.  There’s no way around this fact.  You don’t really notice it, probably, because it’s sneaking in through a thousand cracks, and you’re likely in the shower while it’s happening.  But it’s a travesty.

In fact, it’s a double travesty, because besides replacing warm air with cold air, you are losing the (much larger) amount of heat contained in the water vapor.  One of my Cold House mottos is that water should leave the house in the same phase of matter (more…)


Cellar Tour

December 14, 2009

Here’s a quick tour of some of the Cold House cellar features.

This is the laundry area:

We generally wash with cold water, but we do use some hot for whites. The washing machine discharge is conveniently located, making it easy to reclaim wash-water heat. Method: I start the machine, setting it for 8 minutes of washing. I go away and return in 7 minutes. I put the discharge hose in a big bucket. When the machine starts draining the wash water, I collect the water (it’s more than my current 5 gallon bucket will hold, so I just watch carefully and pause the washer before the bucket overflows). Then put the hose back in the drain before the rinse cycle starts. I cover the bucket of hot water and bring it to the kitchen to cool (just like the dishwasher water.)

Speaking of hot water, here’s the hot-water-heater timer I installed yesterday:

At the old Cold House, our hot water was heated by a heat exchanger in the furnace boiler, and was essentially tankless– so we could turn it off easily when not in use, and not keep hot water percolating when we didn’t need it. Unfortunately the new house has just a standard electrically-heated storage tank, which is not so easily controlled. But this timer will help. It’s very flexibly programmable, so we will be doing experiments to see how much it can be turned off. For the moment, it’s set to be off between 9:00 pm and 5:00 am weekdays (9:30pm – 7:00am weekends), but likely we’ll be able to shut it off during the day some, too. If you’re desperate you can push the white button and turn it on any time (or, turn it off…)

Next, this is our wood pile, just waiting for the stove to be installed. It makes me feel warm just looking at it (it also made us quite warm moving and stacking it.)

Lastly, this is the kitty door:

They have a ramp down to the floor. It does not seal very well, unfortunately, but is still probably better than repeatedly opening the human-size doors to let cats in and out. This spot of the house is the one area where I do have concerns about frozen pipes– the drain from a bathtub we rarely use is just adjacent to the window and cat door. So, I’m monitoring the area with the remote thermometer sensor (the little white box atop the pipe.) Right now it’s 45. I don’t think it’s going to be an issue, but I’m going to get some extra insulation done there just to be on the safe side.

Clothes Drying: Big Improvement

December 7, 2009

Longtime readers will recall my ongoing struggles (intellectual, physical, moral) over the issue of drying wet laundry (first, second, third.) To summarize:

1) I have found no simple, dependable way of reclaiming heat from the dryer (i.e., re-condensing the moisture from its exhaust air);
2) Air-drying indoors in the winter is not much more energy-efficient (it uses almost as much heat as it saves) and not practical in the Cold House (things take eons to dry at our temperature, and we already have more than enough moisture in our air); and
3) Air-drying outdoors is fine in summer, but just not functional here in winter (clothes freeze before they dry, no one wants to wade through snow drifts to get to the laundry, etc.)

Now as the days get colder, I’m particularly displeased with running the dryer: I’ve done some math, and determined that in 45 minutes of running, the dryer sucks all the air from our cellar (which is replaced, of course, with cold air from outside.)

Frustrated with efforts to get back heat from the dryer, I turned my attention to the idea of using it less. One option was to not do laundry till spring: this was quickly squelched by J. The next option was extracting water mechanically rather than thermally. The idea there is that moving water uses much less energy than evaporating it.

I first tried giving laundry an extra run through the “spin” cycle of the washer, but that had no measurable effect. So, I made in investment in a commercial product, the hyper-drive spin-dryer from Laundry Alternative ($135). Success! Running a recent medium load of just-washed mixed clothing through the spinner, I extracted an extra 1.5 liters of water that would otherwise have been boiled off in the dryer. Based on some previous measurements, that represents about half the water content of the laundry load– which should, at least theoretically, reducing the dryer time by 50% (we do have a dryer that senses humidity and shuts itself off at a certain “dryness”, so there’s no guessing with a timer.)

Putting some real numbers to all this: the spin dryer uses 300 watts, and I ran it for about six minutes for this load of laundry– so that’s 0.03 KWh of electricity used. Compare this to the energy needed turn the same volume of water to steam: 0.95 KWh (and that’s assuming absolute efficiency– in reality of running the dryer, it would be more.) In other words, getting this 1.5L of water out with the spinner saves at least 97% of the electricity that the dryer would use to do the same job. Oh, and as an added (trivial) bonus: the 0.03 KWh it does consume winds up as heat inside the house, rather than sent outdoors!

The downsides to the spinner: (1) it isn’t dirt-cheap– at current electricity rates, it will take several years to actually pay for itself. Then again, our big dryer may last twice as long and need half as many repairs if we run it half as much, so you have to figure that in… (2) It’s a bit of a hassle– the spinner basket only hold a third what the washing machine does, so you need to spin a load in two or three stages. (3) The instructions have an inaccurate diagram which resulted in damage to the first unit I bought, having to return it, etc– if you actually buy one, email me and I’ll tell you how to avoid making the same mistake!


October 5, 2009

The two things that plagued my Cold House mind most, last winter, were the heat lost from hot showering/bathing/dishwashing/clothes-washing water, and the heat lost from the clothes dryer.

I (crudely) addressed the first issue by keeping the shower water in the freestanding iron tub till it got cold, and collecting the hot dishwasher/washing machine discharge in 10-gallon pails (keeping them until cold.) The new house doesn’t have such a convenient tub; it’s built-in, and against an outside wall, so getting water heat back through it will be less efficient. However, I have schemes in mind for rigging up a full graywater heat reclamation system (it involves a couple of 55 gallon steel drums, if I can find such.)

The dryer issue, however, remains problematic. Some propose that you can “reclaim” the heat from your dryer simply by venting the dryer into your house, instead of outdoors. There are even commercial gizmos such as this one for the purpose. Since the dryer exhaust is hot, it seems intuitive that diverting it to stay inside the house would allow you to reclaim the heat. Unfortunate it’s not really that simple– because the vast majority of the heat of the dryer exhaust is contained in gaseous water, not in the air. If you

redirect that into the house, the water vapor quickly condenses to liquid water, probably mostly on your windows and cellar floor. That gives off heat, indeed. But then it will again eventually re-evaporate, taking with it the same amount of heat you “reclaimed”. (If it doesn’t eventually re-evaporate, perhaps because your house is incredibly well-sealed, then you will wind up with a warmer but sopping wet house.)

Anyway, the only way to really get the heat back from dryer exhaust is to condense the water contained within it, and then dispose of that water before it evaporates again. Not easy to do. Last winter I experimented with counter-current condensers, in which a six-foot aluminum pipe carrying the dryer exhaust ran inside a larger-diameter aluminum pipe carrying the dryer intake air (the theory being that the water in the exhaust would condense, and drip out the far end.) But it was a miserable failure– only about a tablespoon of the 1+ gallons of water actually condensed. The moral: you need a huge amount of concentrated coldness to absorb the amount of rapid heat produced by the dryer evaporation.

The closest I came to success was by using another electrical appliance to suck up and spit back the heat of the first. By directing the dryer exhaust through a dehumidifier, I managed to condense about 80% of the evaporated water in real-time. This was pretty promising. The dehumidifier, of course, used some additional electricity of its own; but used in this fashion, it spits back much more heat than its own electric draw. The primary problems with this set-up were (1) no matter what I did with filters, lint started to clog the dehumidifier; and (2) there was too much technology, and too many moving parts.

All summer (while we’ve been using a clothes line, mostly) I’ve been wracking my brain for a better way to get condense the dryer vent moisture and get back that heat. But I haven’t come up with one that is cheap and both thermodynamically and functionally practical.

Tub Water

February 22, 2009

Surely one of the most criminal things you can do it take a hot bath in the winter, then pull the plug and run all the still-warm water down the sewer pipe.

I came home yesterday all wicked sore from skiing, and the big hot bath was pretty mandatory. You might think this is quite the waste of energy, all that hot water, but it isn’t at all if you use it to heat the house after you use it for bathing. And that’s easy to do: you just leave the plug in until the water cools to room temp.

Bubbling in the narcotic warmth of the tub, I got to doing mental calculations of the heat in the tub water, and how much it could warm up the bathroom (assuming the bathroom is a sealed system). That required some thought about the heat capacity of various components of the bathroom.

Here’s a pie chart that shows the findings, roughly. It is specific to my bathroom, which is about 7×9 ft with an 8ft ceiling, with tiled floor, and contains a heavy iron tub, small iron radiator, and ceramic toilet and sink. I’ve assumed that about 20 gallons of water has been run for a bath, and that the room is well-insulated beyond the sheetrock (which isn’t really the case, but, you know, just for illustration.)

So, once the temperature of the bathroom equilibrates, about 1/3 the heat will be contained in the tub water, 1/3 in the walls and tile floor, and 1/3 in the sink, toilet, radiator, and tub together. The actual air in the room is what “feels” warm or cold to a person walking around, but it actually contains only a tiny fraction of the room’s heat.

In practical terms, the fact that the tub water has about 1/3 the heat capacity of the rest of the room means that for every degree the water cools, the room will warm by 0.5 degrees. So if you start with tub water at 100F, and the room at 50F, you would eventually end up with both water and room at 50 + ((100-50)*.33) = 66.5F.

But in reality, you can extract more heat than that, because the bathroom is connected to the rest of the house, and given enough time and a coldish house, the bath water will cool further. If you keep the house close to the temperature of incoming cold tap water, you get back as house-heating almost all the energy you put into making the hot bath. Plus, you get a hot bath. Nice.

Simple Experiments In Heat Reclamation: Part II – The Shower

December 19, 2008

Increasingly, I’m becoming convinced that one of the keys to keeping the house warm(er) is paying attention to water.

I mentioned before about the huge energy it takes to evaporate a gallon of water– 2.5 killowatt hours. That got me thinking about the fate of water around the house.

The conclusion I’ve come to: one of the worst things you can do, when trying to keep a house warm(ish) without heat, is to turn liquid water into water vapor, then let it get out of the house in that form. Ideally, any water that enters the house as liquid, should leave as liquid. (Similarly, any frozen water that comes in should leave frozen– or, at worst, liquid.)

Crackpot idea, I know. But think of all the sources of water turning to vapor around the house every day: The dog’s water bowl. Steam from the tea kettle you leave on an extra minute. The simmering tomato sauce. Houseplant soil drying out. Bath towels drying. Dishes drying. Toilet bowls. Mopping the kitchen floor. Wet boots in the entry way. Steam from the shower. Not to mention the humidifier/vaporizer/kettle-on-woodstove that you might have.

And then there’s you, and your housemates. Everyone is constantly churning out water vapor, half through your skin and half through your breath. About a liter a day per person, if you don’t exercise in the house– more if you do, or if your house is hot. In fact, about 25% of your body heat is devoted to vaporizing water– doesn’t that sort of suck? (And don’t forget the dog is breathing, too.)

I think it’s safe to say that by myself here, completely unintentionally, I am probably turning minimum of a half-gallon of water into vapor every day. If my house were completely vapor-tight, after a few days every surface would be dripping and slimy. Luckily (I think), the house is not vapor-tight– so all this vapor eventually escapes outside. It might not do it in one swoop: probably, it first condenses on a cold window, or the toilet tank, or a beer bottle. Then it drips somewhere. But eventually, unless it gets to a drain as liquid, it goes out through a crack as vapor– taking with it that 2.5 kwh per gallon.

It used to be, if I spilled some water on the floor in the winter, I’d half-heartedly sop up the worst of it and leave the rest to evaporate. I look at it a bit differently now… I see the puddle of water and I ask myself, do I want to put that down the sink, or do I want to run the space heater to make it go away? Because that’s what it comes down to.

I’m not being nutso about it, but I am trying to eliminate unnecessary sources of standing/evaporating water around the house. Putting lids on soup pots, for example. Not leaving dishes with water in them lying around.

But the big potential source of improvement here, I think, is from the shower. I admit to liking a nice hot shower, no less now that the house is Cold. But it does produce a lot of water vapor. Step one: trying to keep the vapor in the shower. A fully enclosed shower stall would be great for this; my old clawfoot tub,not so good. But, throwing some bubble-wrap over the top, with a little temporary duct tape for effect, made some difference– shower is warmer, with less hot water, and less steam in the house after. But still quite a bit.

How to catch the steam, and turn it back into water, to make it give back its heat? Various ideas. Simplest: mop it up from where it condenses, before it can dry. I took a sponge to the bathroom window post-shower this morning, and with 10 seconds of effort I squeezed out 50ml of water. That represents the heat of a 35W bulb for an hour. Plus, Cat could see out the window for the rest of the day. The mirror netted some, too. If I had two or three more windows, I expect most of the steam would’ve wound up there.

But you don’t want to go installing extra windows to try and keep more heat in– that’s backwards. You need something that’s already in the house, is coldish but not connected to outside, has a smooth surface, a high heat capacity, a high thermal conductivity, and can be kept up towards the ceiling where the vapor rises. Granite and marble aren’t conductive enough. Something like a slab of copper or aluminum would be good. Silver would be perfect, but pricey. My fantasy image is a border around the top of the walls made of plate copper, with a little gutter under it to catch condensed water and deliver it to drop into the sink. If the room is cold when you start the shower, I think this could be designed to catch, condense, and dispose of most of the steam.

There is a simpler but less elegant solution at hand: a dehumidifier. I tried running it during a shower. First attempt was no use: it was on the floor, and the humid air was not.

Simple Experiments In Heat Reclamation: Part I – The Dishwasher

December 17, 2008

The original idea which started all these shenanigans (back all of two months ago, when heating oil was twice its current price) was that I would “downsize” my living quarters a bit for the winter, spending most of my time in the kitchen. Actually I spend most of my time in the kitchen anyway– it’s also sort of the living room– but the scheme was that I’d install some doors or insulating dividers so that the kitchen could be thermally closed off from the rest of the house, and heated independently when convenient.

One attraction of this is that, aside from the clothes dryer, most of the heat-emanating appliances are already in the kitchen: the stove, oven, dishwasher, microwave, fridge, and the only incandescent lights I can’t easily change to compact fluorescents. So it seemed, just in the course of living, that the kitchen was likely to stay pretty warm.

I hadn’t really anticipated that I still wouldn’t have turned the heat on at all by mid-December. But such is the case, because indeed the kitchen has stayed pretty warm (even though I haven’t finished installing the doors)(and by “pretty warm” I mean around 52F/11C). Just making coffee & oatmeal in the morning tends to heat the room about 3F.

But as real cold weather approaches, I’ve turned thoughts to reclaiming heat that is currently being wasted. There are endless permutations of fancy, complicated, imaginative, labor-intensive and material-expensive ways to reclaim heat from various heat-wasting functions around the house. But my strong preference, at this stage, is for easy, non-permanent modifications which can be accomplished in under one hour for under $10 (or better, for free.) I set my sights, first, on the dishwasher.

Okay, I see everyone up in arms already: a dishwasher! Terrible waste of energy! You could just do your dishes by hand, saving gobs of energy! Yes, of course I could. And sometimes I do. I lived for many years without a dishwasher. But I enjoy having it. I only need to run it about twice a week. And once you finish reading this post, you might decide that it’s not evil– even if I just used it in the normal fashion.

In fact, I am first going to convince you that the dishwasher is environmentally friendly. Here are the facts on my dishwasher. When run on “light wash” cycle, without the “Hi-Temp Wash” or the SaniHeat™” the dishwasher runs for about 50 minutes. On these settings it uses no electrical heating– just the heat from the incoming hot water. It does have an electric motor and pump, which, according to the affixed placard, draw 1 amp (= 110 watts at 110V) when running. In the course of its hijinx, the dishwasher disgorges 5 gallons / 19L of water, at an average temp of 112F/44C (the first pre-rinse is cool, the remaining stages are hot.)

Perhaps those used to doing dishes by hand need a visual: here is 5 gallons of water, divided into two sides of my sink (like, you know, “wash” and “rinse” sides.)
It’s certainly enough to do a couple days’ worth of dishes. But if you leave the water running while you wash, or if you rinse under running water, you’ll definitely use more than this much water. Also, to get the average temp of 112F, you could have nice hot water for the wash side (155F/68C) and cool water for rinse (69F/21C). Or you could have lukewarm water for both. You definitely can’t have hot for both.

Here’s what the dishwasher handled on the test run (which admittedly was premature– could’ve packed more in, but I ran out of dirty dishes):
That’s 3 plates, 8 soup bowls, 1 mixing bowl, 1 coffee press, 1 measuring cup, 8 coffee cups, 5 drinking glasses, 3 wine glasses, various tupperware, and a ladle.

Now, I could perhaps have washed all this in the sink-water above, but towards the end the wash-water would’ve been pretty icky, and the rinse-water pretty soapy. In order to match the water volume & heat efficiency of the washer, I would’ve had to refrain from “freshening up” either side. As far as electrical use– if I spent 15 minutes doing dishes, and had the kitchen lights on while doing so, then I would waste as much power as the dishwasher motor.

Not that the dishwasher motor power is wasted. It turns into heat. And heat is welcome here. The question (somewhere I started out on this question) is how not to lose that heat– plus, more significantly, all the heat from the hot water. Letting it go warm down the drain is a thermocrime. In sink-washing, you could reclaim the heat by just letting the dirty water sit in the sinks overnight, or however long it takes to reach room temp. But many people might find this unsavory– plus, your sink is out of commission for hours. A better approach might be to use dishpans, and set them aside on the counter after to cool. Not a bad idea.

But with the dishwasher, it turned out to be surprisingly easy to reclaim the water heat. I found the machine has a flexible plastic drain hose, running under the sink, then stuck in a PVC drain pipe. It was easy to pull it out. Then, just as easy to put it into an old bucket instead.

Ta da! 5 gallons of warm water, nicely contained. I tossed a plastic lid on it (to prevent steaming evaporation), moved it out of the way, and let it cool. When I remembered, I poured it down the drain.

How much energy can you save this way? Well, that depends how cold you keep your house. The colder your house, the more heat you get back. (Do you detect proselytizing?) The best case is if your kitchen, overnight, gets colder than your incoming tap water– which I’m pleased to report mine does these days. In that scenario, you actually get a bit more heat back than you put in! If my kitchen drops to 45F/7C, then I reclaim (44C – 7C =) 37˚C worth of heat, from all 19L of water. That works out to 703 kcal, or 0.82 kwh. There’s a bit more, too: some of the heat from the original hot water went into heating the dishes, and the dishwasher racks and walls, all of which ultimately gets delivered to the kitchen, too. (Knowing that my hot tap water is 125F/52C, but comes out the dishwasher at 44C, can quickly calculate that the objects absorbed and will return another 152 kcal). All told, this reclamation represents, roughly, 2/3 cup of oil burned in the furnace– or running the space heater on “MEDIUM for an hour– per run. Even at my paltry rate of dish use, that comes to over two gallons of oil a winter, or 50 hours of space heater. And, more importantly, it might stave off, for a few more days, turning the heat on in the first place.

There are many ways to improve the convenience (though not the efficiency) of this “system”. I could, for example, find a metal bucket– that would speed the wastewater cooling, so it wouldn’t have to be sitting around as long. I could find a 5-gallon container that fits under the sink. I could “hard-wire” it into the drains, so it could be emptied with a foot-pump and never seen by houseguests. But that’s all so complicated. I like the bucket.

[P.S. There is one wrinkle I forgot to mention: no matter how you do dishes, drying them will cost you some heat. And, alas, it’s the same amount of energy no matter how you choose to do it.]

[P.P.S. It has been brought to my attention that standard dishwasher soap may be more environmentally unfriendly than dish hand-washing soap. I am investigating “greener” soap options…]

Factual Data

December 12, 2008


My estimate of 1.5 gallons of residual water in a load of wet laundry was slightly high. I did an average-size load of darks yesterday (including two towels) and took measurements:

Weight before washing: 13.5 lbs
Weight after washing: 22.0 lbs
Weight of residual water: 8.5 lbs
Volume of residual water: 1.06 gallons

Valerie said…
Only 1 gallon? Great! If you’re tempted to run a humidifier during the winter, now all you have to do is hang your laundry all over your radiators (or over your woodstove, if you want to live on the edge). If you’re worried about aesthetics, well, I guess it just means you need nicer clothes.

11/21/08 3:26 PM
Anonymous said…
Just remember that anything that slows the velocity of air exiting your dryer will decrease it’s efficiency (using more energy) and potentially create a fire hazard if lint collects nearer the hot center of the dryer.

11/22/08 11:38 PM
jcat said…
Are you sure you were meant to become a psychiatrist? Somehow actuary or ….accountant…. seems more fitting

11/23/08 1:57 PM
Anonymous said…
Fascinating. So this is what you do when you can’t play outside. It’s going to be a loooooong winter.

11/25/08 10:19 AM

Heat Reclamation

December 12, 2008


Heat Reclamation
You may be saying to yourself, “I wonder what kind of whack-o schemes and projects that wing-nut has been up to lately?” Well, I’m glad you asked.

For one thing I (and some hardy friends!) have been trying to see far into the season we can go without turning on the central heat in our homes. This is based on several motivations, including an interest in human physiology, and the fact that the price of heating oil was over $4/gallon when I thought up the idea. But that’s all for a different post. Anyway, I’m aiming now for December 1st, and so far, doing quite well– right now it is 32F (0C) outside, 51F (11C) inside, and I’m typing quite comfortably. We’re allowed to use space heaters, judiciously, but for the most part I haven’t needed to. I have noticed that my house is forming icicles sooner than my neighbors’. Good sign!

So, as part of my overall strategy to reduce oil use, I decided to fashion my kitchen into a winter-bunker. It’s a large kitchen, and already has the sofa, DVD player, etc. in it– not to mention all the food– so I really could just spend the winter in this one room. I made a insulated curtain for one kitchen doorway from a thick quilt, and have bought an old salvage door which I am working on installing in the other doorway. When done, I’ll be able to seal off the bunker from the rest of the house, and, I hope, just stay warm with a space heater. Cool, no?

In the process of all this I got to thinking about the clothes dryer, which is right under the kitchen and vents outdoors right next to the window. In past winters I’ve enjoyed watching the dragon-breath of steam wafting up past the window, and admired the snow-free zone which was kept cleared around the vent all winter. The other day I looked at the dryer to see how much energy, exactly, it uses in doing its thing. Guess what? 5,600 WATTS! Yeah… that’s a lot! Also I got to thinking about the huge VOLUME of air the dryer sucks out of the cellar, which is being replaced by frigid outdoor-temp air rushing in through all the gaps in our cellar windows, etc. Terrible!

I’m considering some type of clothes line for the summer (though my yard is awfully small and shady), but in the winter line-drying isn’t a good option at the Palace. So, for this season, I started to think of ways to reclaim the heat from the dryer, rather than dumping it outside. First idea: just undo the vent hose from the exit hole, and redirect the warm air back into the cellar. E-Z, and stops the air-sucking-out problem, but it seems no good to be humidifying the very air you’re trying to use to dry things. Plus, what good, really, does warm air in the basement do?

So I thought next about instead running the hose up to the kitchen, where the warmth would be useful, and even the humidity might be desirable (in the winter). But as I pictured the amount of humidity involved, and envisioned the dank, dripping windows, etc., as well as the pleasant-only-in-small-quantities aroma of dryer exhaust air, I decided against this as well.

Third incarnation, I thought about sourcing a surplus old iron radiator (Smallish State is littered with such), putting it in the kitchen, running the dryer house in one end of it, another hose out the other, and thence to the outdoors. Thus some of the heat would get transferred from the dryer air to the radiator, warming the kitchen, but the moisture would still get blown outside (some water might condense inside the radiator, but that’s okay.) However, I still pictured half or more of the heat escaping outdoors, which bothered me. And the problem of cold-air-suck remains, because you’re blowing the exhaust outside.

So, for Theoretical Version 4.0, I mentally added a condensing coil of copper tubing to the hose after it leaves the house. Then, another hose at the bottom of the coil returns back inside, downhill all the way, before turning up at the end. A small hole at the low point of the “U” is made, with a bucket below. Water in the humid air leaving the house condenses running through the cold coil, runs down the exit hose, falls into the bucket. The air, now cooler and drier (but still warmer than ambient outside temperature) is returned to the cellar. Voila! Maybe. Suggestions?


Johanna said…

Though I challenge your assertion that you need a dryer in the winter. I don’t own one here in this Canadian climate, the vast majority of Europeans have never owned one, and we have no difficulty at all drying everything on racks. It might take a bit longer right now, with the heat off, but once it’s on things dry overnight (better for the clothes, too).

If you are wedded to the idea of having a clothes dryer, I wonder if you could retrofit a heat exchanger like on condensation dryers. I wonder about the insulation loss of running extra pipes outside and in, through either double glazed windows or a window and a storm window. In my climate, the copper coil would ice up fairly quickly.

I’m also confused about your house building icicles sooner, since, given similar sun exposure and the same ambient temperature, icicles will be more common on buildings with greater heat loss. Maybe the cold miser needs an energy audit?

11/19/08 7:09 AM
charlsiekate said…
How is your tropical roommate adjusting to the no heat thing? The low here in Georgia was 24 last night, which I’m sure is laughable to you New England folks, but we definitely enjoyed the heater. And a warm puppy at the foot of the bed.

Of course, I imagine our house is designed more for the summer heat than the winter cold, and I’m sure my house doesn’t have a heater that uses oil.

11/19/08 9:25 AM
Turboglacier said…
J: I may go with “drying racks” at some point. But space is limited here, and with multiple people doing laundry– well, I don’t know. In general these “European ideas” of which you speak are notorious for leading countries into socialism, prolonged life-expectancy, and other evils.

Heat exchangers– yes, looked into, but they are expensive to buy (like, $500) and not easy to build. And have to have a second fan, so need electricity, blah blah. I don’t think there would be much insulation loss– I’ve already got a hole through the basement wall for the existing exhaust hose, so I’d just use that (the hoses would really go through a window– that was just artistic license, and so I could draw clouds.)

Icicles: In mid-winter, I’d agree with your assessment– icicles form from buildings melting the snow on their roofs, which water then refreezes dripping off the eves. But we’ve had no snow yet, and the temps have barely been dipping below freezing. The icicle in the photo formed from the dregs of a rainstorm dripping off the window sill as the temp dipped down just to freezing over night. I believe my neighbors’ walls did not form any icicles because their excessively-heated walls kept their exterior temperature above freezing, preventing any ice from forming.

CKate: Luckily for Tropical Housemate, he moved on several weeks ago (he was only temporary). He would NOT enjoy what’s going on here now (this morning, e.g.: 28F outside, 50F inside.) In stroke of fantastic luck, I’ve found a new (more permanent) housemate who grew up in Caribou, Maine– frequently in contention with Bismarck, ND for the coldest spot in the Lower 48. So she will, I hope, feel right at home here. Also, she’s bringing two more cats, so we will have all that extra warmth!

11/19/08 10:21 AM
Turboglacier said…
Excuse: above should say “(the hoses would really NOT go through a window…)”

11/19/08 10:23 AM
The MSILF said…
I also don’t have a dryer as this apartment doesn’t have the hookup, and use the racks, which fold up completely…and it’s cold here in winter, not like your cold, but still…inside it’s cold. Now I’d really never go back. It seems so unnecessary. And I think here, where it’s also dry, a lot of people just redirect the dryer vent right back into the room in winter.

11/19/08 12:26 PM
Claire Colvin said…
I realize the schematic is just an artist’s rendering and not to scale, but I’m wondering about the length of hose/ pipe involved here. Any way to test if the exhaust output of the dryer moves at a sufficient velocity to force the air all the way through the lengthened system?

11/19/08 1:58 PM
Turboglacier said…
“Test” it? Of course there’s a way to “test” it: build it, and see if it works! How else?

11/19/08 3:03 PM
Rossie said…
Forgive me if this is answered farther down in the post – I stopped reading with the first sentence of the second paragraph as I am absolutely dumbfounded. You live in New England and are trying not to use heat? in the WINTER?? and other people have joined you in this effort???

Words fail

11/21/08 10:19 PM
Turboglacier said…

Oh yes– just so.

And some of the others who have joined are actually north of New England. J., are you still in? Sort of?

[Right now: 22F outside, 42 in my bedroom, and 53 here in the kitchen bunker with one space heater on. I’m wearing normal clothes, a hat, and down vest. Have been for comfortable for hours.]

11/21/08 11:52 PM
Anonymous said…
something to consider:

the fine particles in dryer exhaust air(lint) can be potentially explosive if the suspended level of them in the air gets high enough.

you might want to exhaust the air into the top of a bucket filled with water (or get a commercial product similar to

Also heat exchangers can be created simply from easy to get materials.

1)figure out how many you need(= to the cross section of your dryer exhaust)

2)divide the number into a number of 1/8th-1/4 in.(2-5mm)slots.

3)double the number of slots from #2 and figure out how many dividers you need(to separate the slots from each other)

4)accumulate(drink) enough pop/beer (as long as it comes in Al cans) to provide the raw material for your dividers.

5) remove the top and bottom of the cans and cut your material into the correct size (4-6″ squares depends on application and raw material).

6) using cardboard(or something similar) as a spacer create a slot that is open on 2 opposite sides(closed on the other 2). I have found that the Al tape you can get for duct work is perfect.

7) keep adding dividers to your creation alternating which side is open. when your done you want to have made something like (O#O#O#O#O#O) on one pair of sides and (#O#O#O#O#O#) on the other.

you should pre-filter the dryer air to keep the HE from filling w/ lint. you will also need to deal with the condensation. if your exhaust is still too warm add another exchanger or a small fan to pull room air through the other sides.

YMMV- good luck.

12/10/08 12:07 PM
Turboglacier said…
Thanks for the tip on explosive dryer dust, Anon. I found that putting a fine kitchen strainer or a scrap of nylon mesh over the exhaust does a good job of filtering the vast majority of it.

While the device is clever, I can’t approve of it for heat-reclamation purposes. Running the dryer exhaust over a pool of water adds even more moisture to the house, causing (ultimately) further cooling. “After a few dryer loads”, the website says, “you simply pull the drawer out and refill back up with water.” But you pay energetically, one way or another, for all that additional water you evaporated…

12/10/08 12:55 PM