Recovering clothes dryer heat..
GICU812
Posts: 289
Anyone ever contemplate recovering the heat your clothes dryer puts out?
When you think about it, you basically have a 5000 watt heater blowing straight outside. Thats okay in the summer, but seems wasteful in the winter.
Obviously you cant just blow it back into the house, that would add too much moisture to the air and the lint problem.
I dont know, just thought Id see if anyone had kicked the idea around. The only thing I could think of was either
A: Add a second lint filter for extra protection, then put in a heat exchanger, maybe a intercooler with a fan behind it. Hot air blows through the radiator like section and out the other end, the fan blows over it to produce warm air.
B: Again, add more lint filtration, then run a few coils of flex duct expand the surface area of the ducting before it goes outside.
I dunno, maybe its a dumb idea, maybe its more work than its worth,·I was just thinking how you're wasting 15000 BTU whenever its running.
ALSO,
My clothes dryer is just about·literally the ONE thing in my house I havent taken apart to see how it works (... yet...)
Can someone explain how the "auto" settings work? Its a, maybe mid 90's model or earlier. Does it have some sort of make shift humidity sensor in there, or is it just a auto-timer? It seems to work rather accurately, that is it stops just as the light clothes are dry, but sometimes before balled up socks or jeans are %100 dry. Seems too close to be preset timing to me.
·
When you think about it, you basically have a 5000 watt heater blowing straight outside. Thats okay in the summer, but seems wasteful in the winter.
Obviously you cant just blow it back into the house, that would add too much moisture to the air and the lint problem.
I dont know, just thought Id see if anyone had kicked the idea around. The only thing I could think of was either
A: Add a second lint filter for extra protection, then put in a heat exchanger, maybe a intercooler with a fan behind it. Hot air blows through the radiator like section and out the other end, the fan blows over it to produce warm air.
B: Again, add more lint filtration, then run a few coils of flex duct expand the surface area of the ducting before it goes outside.
I dunno, maybe its a dumb idea, maybe its more work than its worth,·I was just thinking how you're wasting 15000 BTU whenever its running.
ALSO,
My clothes dryer is just about·literally the ONE thing in my house I havent taken apart to see how it works (... yet...)
Can someone explain how the "auto" settings work? Its a, maybe mid 90's model or earlier. Does it have some sort of make shift humidity sensor in there, or is it just a auto-timer? It seems to work rather accurately, that is it stops just as the light clothes are dry, but sometimes before balled up socks or jeans are %100 dry. Seems too close to be preset timing to me.
·
Comments
As far as the auto setting - on my dryer it is just a temperature controlled switch. While the clothes are wet, they cool the air exhausting from the dryer. As they get dry the exhaust air gets warmer and eventually trips the switch which moves the timer into a cool down cycle.
i got this one
it is a little box that goes on the end of the heater out hose and you put water in it to collect the lint you can get one at your local home improvement store.
it is used when your dryer is is a place that does not allow you to run a hose to the outside.
my mom has one and it works the only thing it requires is that you put water in it regulary
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Post Edited (Lab Rat) : 10/16/2008 8:18:01 PM GMT
If that's the case, then Gicu can make the heat exchanger like a boiler for a steam engine (or locomotive). The boiler has a bunch of parallel tubes, and on one side is the hot gas, and the other side is the material to heat up. Put this in line, and there is a minimal length increase on exhaust for the dryer with maximum heat exchange.
and space consuming mine is small and can fit behind the dryer
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Cheap is definitely the way to go, no sense in spending $100 and tons of time to recoup what comes to be $50 in savings over years. I think yours would be the best idea, if the moisture is not a concern.
Does the air blow through the water, like bubling up, or just over it? It could easily be made cheap either way, and put a "T" with a dampner in the line so you can switch to external vent in warm weather.
I still dont know about releasing all that moisture into the air though. If youd ever seen a improperly vented bathroom fan or dryer vent·in an attic, you would know what I mean, if you dont vent them outside, there is tons of mould and blackness on the wood around where they vent. Maybe im just over thinking that part though.
They didn't have much for insulation in the attic and this did help. What didn't help was the lack of air circulation in the attic and what ended up happening was a rather dense layer of black mould (the nasty kind).
Lets say we didn't buy that place, and I'm sure any home inspector that went in there would find the same thing! (of note, there are some neat ways to clean this without using chemicals...CO2 sand-blaster! It'll fire bits of dry-ice at the wood and "scrape off" the first layer of the wood...the only mess is the sawdust (and mould) laying about!).
My father-in-law has a heat exchanger for the cottage. It has vents to all "hot" places in the house (bathrooms, kitchen, near fireplace) to grab any warm air it can.
It works surprisingly well!!
Anything you install inline with the dryer vent will cause some sort of an obstruction. My dryer sometimes gets backed up with lint in the bottom of the vent....nevermind the restriction this causes, but it's also a fire hazard! Actually, inline lint traps have been banned here in Canada (ontario anyhow!).
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<FONT>Steve
What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
Lee Travino after the second time being hit by lightning!
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Any attempt to capture that heat would present a cool surface for the humid air to condense upon, the moisture would give the lint something to stick to, and the build-up would be immediate. I never attempted it because in my mind I just saw it as a lost cause. It would create more problems then it would solve.
Here another idea along the same theme that I think may be feasible though.....
Capturing heat from an outdoor central AC condenser unit to pre-heat your home hot water, or swimming pool. The freon to water heat transfer would be more efficient than a freon to air transfer, so your AC system will use less electricity too!
Or how about in northern climates, during the winter you could pipe some of the cold weather from outdoors in to keep your refrigerator and freezer cold?
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Brian
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If you're having that much trouble with lint, I guess you would have to check that the lint trap in the dryer is working and seating properly.
As for inline traps being illegal in canada, Ive watched Holmes on Holmes, who works in canada, and is VERY code conscious, and Ive seen him reccomend and install in line traps.
There might be an issue with preheating the water with AC though, you would almost have to have a smaller pre-heat tank, if you mounted it in the heater, you would be heating the freon to 140* all the time, and if you just heated the pipe, it would only work when the water was being used, and people usually use most hot water in the morning and evening for showering, when the AC is usually not going to be on.
But, like the refridgerator, by the time you make the changes, you have long exceeded the probable benefits from it. The key to any of this would be cheap and easy implementation. I guess if you were an HVAC tech with the tools it wouldnt be a big deal.
Another benefit to recovering the heat from the dryer, you would stop a lot of cold airflow into the house, even once I fixed that flapper, I noticed the pipe to the dryer still gets cold, instead of %100 seal and good insulation, there is just a drafty paper thin piece of metal keeping the air out.
Very good point about the cooling condensation though, that would be a big problem, pretty much leaves the only solution being the water\lint trap. It would require a little maintenance, but dont think it would be bad, the only hesistation, again, being the moisture being released into the air.
Lint in the piping not only will reduct air flow, but creates a potential fire hazard. So, one should be using a good lint trap within the machine and it should be cleaned before each new load. Just accept the reality that machines alway need regular maintenance. You will have better outcomes.
If the lint is removed, there is almost no reason that the heated air cannot be recirculated. But keep in mind that warm air with high humidity does a lot of physical damage if not managed well. It easily enables the growth of mildew and dry rot fungus. And it can steam wallpaper until it begins to peel off the walls.
Kitchens, bathrooms, and washrooms all are high humidity zones and care should be taken to recycle moist air elsewhere or to use a heat exchanger that removed the heat but dumps the cooler air with moisture outside.
Of course, if you really want to save money -- use the dryer without heat or at least on a lower setting. Clothes that dry on a clothes line last up to 10 times longer because excessive heat from dryers drastically damages the fiber.
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It's sunny and warm here. It is always sunny and warm here.... (unless a typhoon blows through).
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Searider
You should try putting a temperature sensor in your attic....it gets pretty hot up there with the sun beating down on it. You need a good temperature difference in order for your fridge to work properly...hence the reason they have a certain space behind them!
Perhaps it's a municipal thing then....the rules get more defined as you progress from Federal to provincial to regional to municipal!!
Do you get any condensation on your piping? Might be worth wrapping the duct in insulation!
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<FONT>Steve
What's the best thing to do in a lightning storm? "take a one iron out the bag and hold it straight up above your head, even God cant hit a one iron!"
Lee Travino after the second time being hit by lightning!