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Electric clothes dryer to hydronic conversion

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by SnowTraveler, Sep 16, 2008.

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  1. Duetech

    Duetech Minister of Fire

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    I don't know why it would require 250-260 degrees f to dry your clothes in a dryer. It's the flow of air that dries the clothes coupled with the heat not the heat itself. It just takes time. As was mentioned before you could use a clothes line and they never get to 250-260. Load size, time and power consumption are the determining factors here. The natural properties of flowing warm air on water will cause the drier to work. Air flow, load size and how wet the load is will determine how long it takes to dry. As for power consumption the primary plus or minus for operation is the amount of power used by the heating elements versus the extended amount of drying time used by the blower/drum motor. Under normal usage the blower motor that turns the drum is running any way. Since the original query was based on economic feasibility we are reduced to an uncertain equation. Element ampere consumption for (? time) versus extended run blower ampere consumption (? time). Because we do not know the specific ampere/wattage of either component nor the extended drying time needed we can only guestimate but for simplification most heating elements are rated at or above 1500 watts 220 VAC. Some I have seen take 2200 watts 220 VAC and there are bigger ones. Simplistically If your motor takes 1/4 of the power of your elements you can fairly assume a break even point of 4 to 1. 1 hr regular vs 4 hrs extended run time. Find the draw rates of your elements and your motor and you can determine the specifics. There is probably a tag on the back or bottom front of your dryer that gives the specifics. To prove the capabilities of lower temperature just turn your drier to "no heat-fluff" setting and stick a wet towel in. Eventually it will dry. I use an electric dryer by Frigidaire and heat my home and dhw by an EKO 40. What I save in propane and fuel oil offsets the cost of using my dryer as intended and, though I'm a dreamer at times, I am also lazy enough to see the value in that. Not having seen the hydronic dryers up close I can't be sure but I think they have probably increase air flow to reduce drying time to satisfy the hurried age we live in....Cave2k

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  2. free75degrees

    free75degrees New Member

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    yeah... what he said.
  3. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Using 160-degree air (for example) will dry the clothes, but will take longer to do so. The added cost of running the motor/pumps for such an extended period "probably" outweighs the energy savings, unless your wood is "free."

    Also, you would have to have the boiler running, or just ended a fire, in order to produce those kind of temperatures, which means that you couldn't just dry your clothes whenever you wanted. Some might not want to deal with the inconvenience.

    Still, I think there's nothing unsolvable in these issues. It just depends upon how much you are willing to spend on development. For example, more-efficient ECM motors for the drum, fan, and circulator would reduce the electrical usage. A large heat exchanger to make good use of lower water temperatures would solve the scheduling issue to some extent. The "condensing" technology that Trevor mentioned could further reduce the energy cost, if it could be integrated properly.

    It all depends upon what one is willing to invest in testing/development.

    Joe
  4. sdrobertson

    sdrobertson Minister of Fire

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  5. Gooserider

    Gooserider Mod Emeritus

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    Not bad, though I would be a bit nervous about some of his construction techniques - it wasn't clear what he was using for his stove pipe material, and I know galvanized metal is definitely NOT OK on stove piping... Also you have the same potential condensation / creosote issues that any of the heat reclaimer type products would have, possibly more so because of the air volume going through it...

    Not a hydronic version, but still a reasonable approach, and sounds like he is using similar temperatures...

    Gooserider
  6. Fred61

    Fred61 Minister of Fire

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    Lower heat may be easier on the clothes but the increased tumbling time means you will be removing more of that shirt from the dryer as lint.
  7. Bad Wolf

    Bad Wolf Minister of Fire

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    It would be interesting to compare the cost extra time vs. electrically heated air. The only reason to heat the air is that the hotter the air the more water it can hold.
    If I had the time I could see getting a Craigs list freebie dryer putting, it near the boiler and hooking it up. In the wither I'm running the boiler wide open at least twice a day and could schedule laundry around that. I would keep my regular dryer for the other time or when you need something dried fast. Like my son putting his one wet shirt in an already dry load ten minutes before he has to go to work.
  8. Dune

    Dune Minister of Fire

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    I think this is a great idea. Electric dryer elements are either 5000 or 5500 watts. Clearly the extended use of the motor would be far cheaper than a shorter duration with the 5000 watt elements also consuming electricity. If I wasn't so deap into my co-gen project, I would get right on this. Instead, it will be added to the back of my already long list of alternate energy/home improvement projects. The link to the offgrid guy makes it clear how simple this project is. Remove the drier element, replace with an automotive heatercore of an apropriate size. Instead of a zone, I would supply it with mono-flo tees, and put a ballvalve on one side. When you want to dry clothes, open a ball valve and hit the start button. Like many such ideas, this might not work for everyone, but for some of us it could be great. If you already have a sidearm water heater, your next largest consumer of electricity is the clothes dryer.
  9. pdboilermaker

    pdboilermaker New Member

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    Why not put a small water to air heat exchanger inside the dryer near the air intake? That way the air that is being "sucked" into the dryer is already at 160-170 degree range, well above abmiaent air temp? This way, the heat coils may never need to fire on the dryer because the input air is over or nearly to the thermostat requirements of the dryer?
  10. Sting

    Sting Feeling the Heat

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    Because: A "small" HX running at 170-180 will not have close enough transfer efficiency to produce more than smidgen of temperature rise on the CFM drawn into the appliance.

    Folks -- Ill state it again -- there is a reason that appliance manufactures run household dryers at 240 to 260 degrees and the products of combustion run out at 160 to 180. Industrial laundry appliances use steam input at over 300 degrees for effecent and fast operation of 75 to 150 lb loads. If they configured the gas or resistance train to run cooler - The clothes do not dry, and the energy input is wasted. Drying clothes on air dry only takes forever - the energy expended in the air only tumble action will be more that would have been expended running the appliance as designed.

    Give it up and get a wash line outdoors in the summer! Hang the clothes in the basement when the air is so dry that your skin is cracking. Hang in the boiler room when your not opening the glory hole to stoke! Hang clothes in sunny freezing weather and let those pants freeze-dry. Fresh laundry off the line requires no fabric softener and smells better too.
  11. Sting

    Sting Feeling the Heat

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    yeah -- guess my miss spent youth continues to provide fodder for the vultures to pick at. Grandma used to hang out the "WASH" so its always been the WASHLINE hehehehe -- Your may like soda vs pop -- or bubbler vs water fountain -- what ever

    All I know is this thread about a hot water HX charging a clothes drying appliance is a waste of time.
  12. Dune

    Dune Minister of Fire

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    So are you saying that the people who build the machines for sale at the link provided by the original poster are just full of it? That their product is junk and their website is all lies?
  13. Sting

    Sting Feeling the Heat

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    ummm

    What conclusion would you draw?

    :)
  14. Dune

    Dune Minister of Fire

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  15. SnowTraveler

    SnowTraveler New Member

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    Still lurking, here every day but not a frequent poster. Last season (my second) was phenomenal with my econoburn 150, 7 to 8 cords of wood to heat roughly 3000 square feet of house, part of a garage, and my hot water. I WILL be doing the clothes dryer conversion this fall. I will post my results later, so let this thread dry up till then.
  16. Sting

    Sting Feeling the Heat

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    Still disbelievers -- well wishers -- folks that think they can win the lottery without buying a ticket

    Of course the advertised conversion works

    so does a clothes dryer on air only

    I won't again impose thoughts already posted to debunk this idea - Free country - have a nice day and all that

    But IF you can look past the rose tint of the glasses your wearing - You should ask yourself WHY every appliance manufacturer IN THE WORLD runs at the temperatures I have posted to make their product, competitive and useful in the market? Because if they could cut their gas or resistance input and advertise how well it works ---> they would corner the market.


    And that's all I have to say about that. Should make some happy to have me "dried up".
  17. EnergyNut

    EnergyNut New Member

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    This is the first time I have used a blog.

    Most dryers (gas or electric) use a 1/4 HP motor to turn the drum. That is equivalent to 0.25 * 746 = 137 watts.

    The heating element in an electric dryer uses between 3.3 and 5 kilowatts.

    Therefore you could run a hydronic clothes dryer (heated by solar, wood boiler, etc) all day (if necessary) and still use less electricity than drying one load with electricity.

    I think hydronic clothes dryers make good sense. Don't get discouraged by opinionated replies.
  18. pdboilermaker

    pdboilermaker New Member

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    WOW, thats 2 months worth of a bill in Indiana during the summer when I am running 2 central air units. Obama's coal ban/tax will kill you
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