Clothes Dryer {Coal Fired}

All of that makes more sense now.

Mike

some one mentioned 10k BTU needed and 200 min temp? under counter kick heater is in that range, would small fins in coil plug up every day?? could you get enough air threw it? so if im pushing 180 degree water are we close enough?

I think a normal dryer is closer to 40k btu/hr. The heat exchanger could be placed "downstream" from an air filter if dust or lint is likely to be an issue.

Mike

Vampiro wrote: This can be atttained with low pressure steam, which at 1 psi is 215 deg f. That temperature is sufficient to dry clothes.

The flaw in your assumption is that the steam temperature will give you the same air temperature. It will not. If you can transfer energy from one media to another with zero losses, youll have more money than Bill Gates and Mark Zuckerman combined. At 110# of steam you will have approximatly 375-385° in your first coil. That will raise your ambient air temperature about 140-150.°. With a second coil you will probably pick up another 50°. One pound of steam will waste your time and money, you will be drying your clothes with the ambient air. The only way you will get the air temperature up to around 200° is if the air doesn't move at all and that won't dry the clothes very well.

coaledsweat wrote:

Vampiro wrote: This can be atttained with low pressure steam, which at 1 psi is 215 deg f. That temperature is sufficient to dry clothes.

The flaw in your assumption is that the steam temperature will give you the same air temperature. It will not. If you can transfer energy from one media to another with zero losses, youll have more money than Bill Gates and Mark Zuckerman combined. At 110# of steam you will have approximatly 375-385° in your first coil. That will raise your ambient air temperature about 140-150.°. With a second coil you will probably pick up another 50°. One pound of steam will waste your time and money, you will be drying your clothes with the ambient air. The only way you will get the air temperature up to around 200° is if the air doesn't move at all and that won't dry the clothes very well.

Well, in a closed insulated system that wouldn't be as much of a problem, correct?

If you assume a room 2X5X7, you'll need ~6200btu to raise the temp from 70 to 160. You should be able to plumb the box to do that while the clothes are in the washer, and with a fan and a dehumidifier, you're drying rate while slower than a tumble dryer should be acceptable for smaller families.I haven't run the calculations to see how much copper you could stuff inside that space, but I would guess you could be putting upwards of 10k btuh through it. In my case, that would be simply rerouting the primary loop through the dryer/cabinet.

I have my doubts you'd get much savings for larger families because of the frequency of use, the temperature delta drop once the clothes started to dry would make it hard to keep up with one load of wash after another.

For gas dryer BTU input.

When I rebuilt my old Sears Kenmore three speed gas dryer, I ordered a new burner.

The Sears parts department offered two gas burners. One was listed as 20K BTU, the other was 22K BTU. Same price, so I went with the 22K unit. Even on the lowest heat setting, it was so hot it shrunk all my cotton clothes within just a few washings. The flame it threw was huge and LOUD !

Paul

kstills wrote: Well, in a closed insulated system that wouldn't be as much of a problem, correct?

Yes, and a closed system just adds more problems.

Lets look at this objectively.. Is it practical to dry clothes with coal heat from a boiler zone or whatever? How much does an electric dryer cost per month to operate? Mine averages about 1 hour per day at most for a family of 4 people, so figure 30 hours of run time per month. After looking around it seems that dryers average 4500-5300 watts per hour. Lets take the middle for simplicity.

5 kilowatts per hour x 30 hours run time per month x $.13 per KW = $19.50 per month

So I guess the real question is, is it worth the effort?
And how badly would it tax your heating appliance?
Would you be using it in the summer too?

Well if someone would just build a prototype we could find out once and for all if it works!

I have a spare dryer, but you can't have it. It's a 1955 Frigidaire DV-65 electric. Has real chrome trim! I'm saving it for the Smithsonian.

Would think it would be very useful.
The main advantage of the dryer is that you have the cloth altogether in a small place where they will not get dirty or smelly from the environment during the drying process. As suggested 1 hour per day could with a little planning expand to 3 hours per day and reduce the required heating capacity at the same time. The efficiency from an energy standpoint has to go up with lower temperatures assuming that spinning the drum takes little energy. We have a dryer and washer in one that uses water to dry cloth and save a lot of energy. It takes a little longer that is for sure. I agree that venting in the house in the winter once a day might be good to keep the humidity in the healthy range.
If your dryer has a humidity sensor that shuts the machine of when the cloth are dry enough it should be easy enough.

Quoted from an energy star website: http://www.energystar.gov/ia/products/downloads/E ... Dryers.pdf
page 12

It is possible for the necessary heat for clothes dryers to be derived indirectly, from a home
hydronic heater system. The dryer would use some form of heat exchanger or radiator to utilize
heat from the heater system’s hot water that is brought to the dryer through plumbing.
One source claims that energy savings up to 50% and time
-
savings up to 41% are possible.

Interesting article and totally doable for the interested

Later J.

a very interesting thread. My take so far on all facts and discussion presented here is that a dryer when fed with hot water from a boiler on site will be limited to 212 degrees at maximum (give or take a few degrees either way). Whereas a gas or electric dryer can produce higher temps since the fuel is burned right there or electric elements are glowing locally. That should translate to higher temperatures in the dryer chamber and shorter clothes drying times than the temps from boiler water.

When I first learned how to do laundry, I shrank an entire load of clothing and badly scorched a comforter. Years later I did my girlfriend's laundry and shrank all of her delicates That was expensive to replace My point is that perhaps I never need the higher temps that a gas or electric dryer can provide because as a result of my past laundry mishaps, I dry everything religiously on low setting. I would think that boiler water would be sufficient to dry on a low setting. I'm comfortable drying my clothes on low and don't mind the extra 30 minutes or so it needs using a low temperature.

The energystar link does mention all kinds of technologies and features that can increase efficiency such as recycling the air and trying to utilize as much heat energy as possible before dumping it outside. I would think that it would be hard(er) to integrate a boiler water fed dryer along with these types of efficiency technologies. I can totally see someone doing this on an older style dryer with mechanical controls for instance. But on a new dryer where everything is electronic and an attempt by someone to modify it would be interpreted as tampering or non safe condition would probably prevent the dryer from running. This would be a considerable obstacle to overcome.

I think this could be done ... BUT ... it's not going to work like we're used to. Instead of drying a full load bone dry in one hour ... it might take 2 ... or 4 .. or more hours. You'd have to run the fan slower to keep up with the lower BTU output of the exchanger, which I think would extend things quite a bit. Then there's the problem of lack of velocity of the air to remove all the lint .... hmmmmmmmm!

Just FYI, my Maytag dryer is stamped 5,600W. That's a lot of juice!

We hang clothes in the basement all the time. Then we have a wooden drying rack that I place in front of the stove. The stuff on the rack dries very fast. Good enough coal fired dryer for me

SMITTY wrote:I think this could be done ... BUT ... it's not going to work like we're used to. Instead of drying a full load bone dry in one hour ... it might take 2 ... or 4 .. or more hours. You'd have to run the fan slower to keep up with the lower BTU output of the exchanger, which I think would extend things quite a bit. Then there's the problem of lack of velocity of the air to remove all the lint .... hmmmmmmmm!

Just FYI, my Maytag dryer is stamped 5,600W. That's a lot of juice!

Good point, extending the operation of tumbling and air flow would also cause an increase in power consumption.. It wouldn't wash out the savings on the heating element, but would dip into it by some..

SMITTY wrote:I think this could be done ... BUT ... it's not going to work like we're used to. Instead of drying a full load bone dry in one hour ... it might take 2 ... or 4 .. or more hours. You'd have to run the fan slower to keep up with the lower BTU output of the exchanger, which I think would extend things quite a bit. Then there's the problem of lack of velocity of the air to remove all the lint .... hmmmmmmmm!

Just FYI, my Maytag dryer is stamped 5,600W. That's a lot of juice!

Somebody did mention steam before. If a solution could be figured out to pipe steam to an air heat exchanger and raise the temps being fed to the dryer past 212, now this is a more workable solution. Steams packs alot of BTU punch too!

Unfortunately, by mentioning steam that eliminates many households.