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Thread: V3000 heats up garage

  1. #16
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    I will grant that the dust ending up in a bin is work and stored energy but, All the air flow continues through the filter and slowly comes to a stop as friction slows it down. I wonder how much useful work a tablesaw yields vs waste heat? Isn't thermodynamics fun.
    Bill D
    Last edited by Bill Dufour; 08-05-2020 at 11:31 AM.

  2. #17
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    Quote Originally Posted by Stephen Bandirola View Post
    The calculations here are wrong, they are assuming 0% efficiency ( that means no work gets done, but we know the fans are moving air).
    The power that goes directly to heat is the amount left over after the work (sucking dust) is done.
    Practically speaking, all the energy does end up being converted to heat. If the collector is higher than the dust making machine, then a miniscule amount of the kinetic energy will be converted to potential energy when the dust is lifted to the higher level.

  3. #18
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    Lets think about this a second, you are saying that if a duct is horizontal it doesn't take any electricity (only the small amount to heat the air) to move for instance 1000cfm through a 6" duct.

    I did only get a B in Thermodynamics so maybe I missed the part about getting something for free.
    Last edited by Stephen Bandirola; 08-07-2020 at 11:20 AM.

  4. #19
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    Simply touch the motor. A 100 watt incandescent bulb will be too hot to touch. A 2000 watt heater will blow a lot of very hot air, hot enough so you can't leave your hand in from of it. Most of the electricity is going to spin the impeller and force air to move. It's fighting the filter and other restrictions, like the duct work. Yes it will heat up the air but not to the point of a 2000 watt heater. You can do about the heat other than put it outside or duct the air outside and make a temp insulated wall to block the heat. Of course then you are subject to heat loss in the winter and sucking in hot air. Other than that keep your filter as clean as possible. A clean filter means less work for the motor.

  5. #20
    The motor isn't as hot as the light bulb because it is designed to shed the heat. That said, the total heat energy in the motor is way higher due to its mass. Heating up 50 lb of iron and copper takes more energy than a few ounces of light bulb, even if the bulb's surface temperature is higher.

    2000 watts is 8.3 amps of 240V. That all ends up as heat somewhere, whether left residual in the motor, blown into the air, absorbed into the walls from sound, or absorbed as heat in the ducts and bin from friction of the air and chips moving. Heat is the only place the energy can go, except for any storage of potential energy as noted by Frank above. If you are drawing full current, you are getting more than 2000 watts of heat out of a 3HP dust collector.

    Myself, at some point I will move my cyclone outside, mostly so the motor heat can dissipate outside in the summer. I will sill vent back inside, but the motor is where most of the heat is generated; there isn't that much heat added to the air in the ducts from friction compared to what is shed from the motor surface. I have limited ability to cool the shop in the summer. The air in the ducts might get cooled a little bit in the winter, but I can easily make that up with my gas unit heater. I also could use the space the cyclone takes up
    Last edited by Andrew Seemann; 08-07-2020 at 4:35 PM.

  6. #21
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    The electrical energy is converted by the motor into mechanical energy the rotates the impeller. That moving impeller passes that energy to the air in the form of kinetic energy. So where does the energy end up? Some is converted directly to heat via motor inefficiency, some will go to moving the air, and a little will be lost to noise generation. As the air is flowing through the duct, friction causes it to lose some kinetic energy in the form of heat. Same with when it passes through the filter or cyclone. And finally, as the exhaust air is discharged into the room, the last of the kinetic energy will be converted to heat from friction with the still ambient air.

    A 2000W motor will most definitely put the same amount of heat into the shop as a 2000W heater (assuming the air is exhausted back into the shop). Unless science has been wrong all these past decades.

  7. #22
    Quote Originally Posted by Alex Zeller View Post
    Simply touch the motor. A 100 watt incandescent bulb will be too hot to touch. A 2000 watt heater will blow a lot of very hot air, hot enough so you can't leave your hand in from of it. Most of the electricity is going to spin the impeller and force air to move. It's fighting the filter and other restrictions, like the duct work. Yes it will heat up the air but not to the point of a 2000 watt heater. You can do about the heat other than put it outside or duct the air outside and make a temp insulated wall to block the heat. Of course then you are subject to heat loss in the winter and sucking in hot air. Other than that keep your filter as clean as possible. A clean filter means less work for the motor.
    Thanks, I’ll make sure to clean the filter more often.

  8. #23
    What do you all think about putting a little bathroom exhaust fan close to the dust collector. I have an outside wall I could do that with just to pull the heat away. I’m just installing a 3 hp now and that might be a little too much heat

  9. #24
    This is an opportunity to consider venting it outside. I have done that, and it is AWESOME in terms of space saving, noise reduction, cleanliness. Mine vents zero heavies outside - just noise.

  10. #25
    Quote Originally Posted by Bill Brammer View Post
    What do you all think about putting a little bathroom exhaust fan close to the dust collector. I have an outside wall I could do that with just to pull the heat away. I’m just installing a 3 hp now and that might be a little too much heat
    Won't work. Only a small amount of heat is directly generated at the motor due to inefficiency - the majority of the energy is converted to heat through the process of moving the air around. Even if you had a 100% efficient motor, if it drew 3HP, it would be converting all of power into heat.

  11. #26
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    Quote Originally Posted by Dan Friedrichs View Post
    Won't work. Only a small amount of heat is directly generated at the motor due to inefficiency - the majority of the energy is converted to heat through the process of moving the air around. Even if you had a 100% efficient motor, if it drew 3HP, it would be converting all of power into heat.
    This is correct. As far as machines go induction motors are quite efficient. that 3 HP motor is only dissipating about 300W worth of heat from the motor itself. The remainder of the power will end up heating the air as it passes through the blower & duct work.

  12. #27
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    I know this in an old thread, but I think what is actually happening is the cyclone is just turning over the shop air. In your average garge, the pad is very cool, and the roof very warm in the summer. A dust collector quickly mixes all that so the "real feel" temp gets higher. It has nothing to do with electrical inefficiency, well very little.

  13. #28
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    I assume while the dc is dumping heat into the shop another motor is also running a power tool and dumping even more heat into the shop.
    Bill D

  14. #29
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    An electric motor is roughly 50% efficient so a 750 watt one hp motor uses about 1500 watts of input energy. The extra 750 watts goes to heat. The 750 watts goes into entrophy and thus heat.
    Bill D

  15. #30
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    Quote Originally Posted by Bill Dufour View Post
    An electric motor is roughly 50% efficient so a 750 watt one hp motor uses about 1500 watts of input energy. The extra 750 watts goes to heat. The 750 watts goes into entrophy and thus heat.
    Bill D
    I'll qualify that. The average universal motor (the kind with brushes) is in the neighborhood of 50% efficiency. Induction motors are much better, probably about 90% for a good 3 HP motor. Large induction motors are around 95% efficient.

    Steve's point about stirring up the hot air at the ceiling no doubt adds to the effect, at least in the summer. And any other motor that is running also adds heat. Assuming no exchange of outside air, 100% of the power consumed by any motor & lighting loads in the shop will be transformed into thermal energy, or heat.

    If I forget to turn off the lights in my shop overnight, it can raise the temperature by about 4*C by morning. That experiment has been foolishly repeated several times

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