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Author Topic: infared heat??  (Read 4600 times)
luvrbus
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« Reply #15 on: November 16, 2011, 04:58:12 AM »

Back in the 30's induction cooking would never work I don't own one of the heaters but I am not one to rate something from paper or the internet for me it's garages sales if it doesn't work they will pop up there LOL,people I know that have one love the heater  

Noah has 2 that were given to him why not try it then he can tell us if they work hard to believe all this from 2 free heaters,there is more than 1 manufacture of that style heater
« Last Edit: November 16, 2011, 05:05:41 AM by luvrbus » Logged

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« Reply #16 on: November 16, 2011, 07:07:27 AM »

Noah has 2 that were given to him why not try it then he can tell us if they work hard to believe all this from 2 free heaters,there is more than 1 manufacture of that style heater
i don't think anyone was suggesting he not use them.  this was mostly about don't buy a $472 heater when an $80 will work, and a good explanation of why they're all about the same, so stick with the least expensive that suits your purpose.  Free is the cheapest.  Grin
and Sean, thanks for a better technical explanation of the good consumer information Scott provided.  i did not think about the differences voltage would make and why 1500w.
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« Reply #17 on: November 16, 2011, 07:40:50 AM »

That's not my point Tom everybody here says they don't work but yet Noah is the only person here with one LOL 

I guess should read Sean's technical stuff but I don't it is to technical for me but I do read his about his mechanical problems

good luck
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« Reply #18 on: November 16, 2011, 11:36:14 AM »

That's not my point Tom everybody here says they don't work but yet Noah is the only person here with one LOL  I guess should read Sean's technical stuff but I don't it is to technical for me but I do read his about his mechanical problems good luck

I vote "YES" on this too. Use them and tell us how you like them...it would be a real data point at least... Smiley
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« Reply #19 on: November 16, 2011, 02:41:50 PM »


Just remember "two dogs" ad the electric radiator fans.  got free fans and disappeared from the earth.  Never did find out if they worked or not.

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« Reply #20 on: November 16, 2011, 03:38:11 PM »

Constantly amazed with the wealth of knowledge from everyone on here. 

The wife threw one in the bus today...... ill let everyone know how they work...

As far as the price point..... I agree... spend almost 500 bucks on a "portable infared heater" id probablly never do it.... but as said "free is the best price"

Ill let everyone know how it works...... the iowa winter will definately be the test of tests... and if it works here it'l definately work in western washington where we plan on using the bus as a fulltime unit while we work and build our "dream home"

Thanks to everyone for the input I greatly appreciate it!

Noah and family
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« Reply #21 on: November 16, 2011, 06:15:49 PM »

A minor point, but not all electric energy used in a coach is converted to heat. Per the previous example, a coach's fans and its model electric trains are converting electric energy to mechanical energy, or work, and not heat energy; same goes for many other loads. Granted, in the change to mechanical energy some minor heat losses are seen, but not all of the electrical energy is 100% converted to heat.

But yes, the simple old rugged $12.00 milkhouse heater is every bit, 100%, as efficient as  heaters with tons of advertising energy packed in them.

Ted
« Last Edit: November 16, 2011, 06:30:44 PM by TedsBUSted » Logged

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« Reply #22 on: November 16, 2011, 06:42:54 PM »

A minor point, but not all electric energy used in a coach is converted to heat. Per the previous example, a coach's fans and its model electric trains are converting electric energy to mechanical energy, or work, and not heat energy; same goes for many other loads. ...

Sorry, Ted, but that's not entirely correct.

Yes, a mechanical device such as a motor converts electrical energy into work.  However, that work is then converted directly back into heat inside an enclosed space, which scientists would refer to as a "black box".  The work only leaves as something other than heat if it can act outside of the black box, or, in this case, the coach.

For example, if you put a fan -- no heater, just a fan -- into an insulated box with a temperature probe in it, and measured the rate of rise of the air temperature inside, you would see that every watt-second of energy going into the fan becomes heat inside the box.  In fact, you can not tell whether what is connected to the wire is a fan or a light bulb -- 1 kWh consumed by either will add 3412 BTU to the box.

The same thing is true for the electric train -- all the "work" done by the train is against friction on the track, and work expended against friction becomes heat, plain and simple.  In the case of the fan, the air movement itself represents some heat (remember that heat is nothing more than molecular motion), and the air then moving against all of the surfaces of the box becomes heat through friction.

This is why I wrote earlier that any motor must act outside the coach for that energy not to become heat inside the coach.  I also said that energy going into a storage system, such as a battery bank, will not become heat, so you could also have a motor that, say, wound a clockspring, or pumped water from a lower tank to a higher one, and that work would not become heat either -- but that's not what happens with the fan inside a heater.

Hope that clears it up.

-Sean
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« Last Edit: November 16, 2011, 07:20:56 PM by Sean » Logged

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« Reply #23 on: November 16, 2011, 10:10:09 PM »

Sean, I respectfully disagree with your take on the heater's fan load. Although we're getting into a hypothetical that really doesn't matter, I will cover a bit of it. I think our difference lies in the fact that I don't believe that a bus is  a "tight" enough enclosed space to have "black box" status and thus to apply the "captured" energy theory.

Once the hypothetical fan would be removed from the black box and put to work blowing air around the coach, the same fan's motor will show a higher amp draw. This increased amp draw represents electrical energy being converted to "work" moving air, and is not electrical energy  simply being converted to heat through frictional losses or otherwise. An ammeter and a  cardboard to slip  over almost any fan's air intake side would quickly demonstrate this.

Anyway, for all practical purposes I can't find any logic in considering a bus to be an "island" of  energy any different from, or separate from, the rest of the universe. Actually I wish I hadn't mentioned it and I'd just as soon forget about it.  Wink

Ted
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« Reply #24 on: November 16, 2011, 11:53:02 PM »

... Actually I wish I hadn't mentioned it and I'd just as soon forget about it.  Wink ...

That's fine, and if you and I had had this conversation privately in email or PM, I suppose we both could.  But there are already 23 people following along, and there may be hundreds more who visit this topic in the archives over the years, and at least some of those folks want to know the right answer.  My purpose here is not to beat you up -- your mistake is a common one and I've heard it many times.  Rather I am simply trying to shed light on a rather esoteric subject that, it turns out, affects coach converters in several ways.

Quote
... Although we're getting into a hypothetical that really doesn't matter,

Well, actually, it does matter.  It bears on the original discussion, wherein a manufacturer has asserted that his product is somehow more efficient than someone else's, which is a physical impossibility (my original assertion), and which was then also challenged by a respected consumer watchdog publication.  But it also has a bearing on other facets of coach conversion; for example, folks here ought to know that every electrical device in their coach adds its total wattage to the coach's heat load (with the exceptions I already noted).  That becomes important when planning for air conditioning, for instance.

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I will cover a bit of it. I think our difference lies in the fact that I don't believe that a bus is  a "tight" enough enclosed space to have "black box" status and thus to apply the "captured" energy theory.

Well, first off, it's not a "theory."  As I said, it is the First Law of Thermodynamics, a law which has been around for much longer than you and I and is immutable.  We call them Laws for exactly this reason.  By contrast, Gravity, like Evolution, is a theory and we can debate it (although I don't expect to fly off the Earth any time soon) Smiley

With regard to the "tightness" of the coach, please note that I already mentioned this.  In fact I explicitly said that units with fans were subject to actually moving the warm air past cold (or leaky) surfaces.  So, no, it is not the same as the black-box experiment, but that does not change the fact that every watt still becomes heat first, even if later it finds its way outside through a leak.

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Once the hypothetical fan would be removed from the black box and put to work blowing air around the coach, the same fan's motor will show a higher amp draw.

Actually, no.  The black-box experiment is not dependent on the box being small, it can be any size -- as large as a bus.  Blocking the fan's air flow, in fact, will not lower the current, but rather it will raise it as the fan struggles to move air against constraints.  Anyone who works with HVAC systems can tell you that the load on the fans increases as the filters become more restricted, for example.  But the point behind the black-box though experiment is not to equate a coach with the black box, but rather to illustrate that all the energy becomes heat -- true even if you take the black box away completely.

Quote
This increased amp draw represents electrical energy being converted to "work" moving air, and is not electrical energy  simply being converted to heat through frictional losses or otherwise.

Let me say it again:  The electrical energy is not all being converted to heat directly -- you are correct, much of it is first converted to work.  But 100% of that "work" MUST then become something else, according to the First Law.  There are not a lot of choices for the something else: it can be stored, such as in a battery, spring, raised weight, etc. as I already said; it can leave the coach as "work" but only through some mechanism to do so such as a shaft protruding outside of the coach to drive something external (pretty far afield from a space heater), or it can become heat.  In practice, it ALL becomes heat.

Quote
An ammeter and a  cardboard to slip  over almost any fan's air intake side would quickly demonstrate this.

Challenge accepted Smiley  Come to my next seminar, and I will bring the appropriate tools -- a fan, a lamp, a pyrometer, an ammeter, and an ice chest, and I will demonstrate to you experimentally that the First Law can not be violated.  Note that you need the entire setup -- having just the fan and the cardboard is not a closed system and will not give accurate results.

Quote
Anyway, for all practical purposes I can't find any logic in considering a bus to be an "island" of  energy any different from, or separate from, the rest of the universe.

Nobody said it was an "island" or that it was "separate from ... the universe."  I merely said it was a closed system.  And, though you can find no logic in it, it is the engineering basis for many things, such as computing the required amount of cooling to deal with internal heat loads.  But the reason I made the statement in the first place was to clear up the marketing-generated misconception that any one 1500-watt electric space heater can be more efficient than any other 1500-watt electric space heater -- it simply can not: each will produce precisely 1500 watts of heat.

This is very definitely a real-world concept.  One of the things that I did back when I was working was to design large-scale computing facilities.  Lots of fans and other motors in such places -- every computer and every cabinet has fans, and every disk array has lots of motors.  All of those fans and motors are doing "work" -- and every joule (or, if you prefer, foot-pound or maybe horsepower-hour) of that work ultimately added directly to the heat load.  If we put 200kW of electricity into the room, we knew we had to take 682,500 BTU/hr of heat out (or about 57 tons of cooling) before we even factored in any other loads such as personnel.

This concept is every bit as relevant in a bus.  If you put 3kW of power into your coach, no matter what it's running -- microwave, fans, lights, television, water pumps, coffee maker, household fridge, or even a toy train set. -- you'll be adding over 10,000 BTU/h of heat to the coach, with the exceptions I already noted (air conditioners, exhaust fans, externally-vented heating elements, etc.)  If you happen to be doing this in the summer, that's another 10,000 BTU/h of air conditioning you'll need just to break even.

Again, I hope that clears it up.

-Sean
http://OurOdyssey.BlogSpot.com
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« Reply #25 on: November 17, 2011, 04:18:02 AM »

... Actually I wish I hadn't mentioned it and I'd just as soon forget about it.  Wink ...

. . .there are already 23 people following along, and there may be hundreds more who visit this topic in the archives over the years, and at least some of those folks want to know the right answer.  My purpose here is not to beat you up -- your mistake is a common one and I've heard it many times.  Rather I am simply trying to shed light on a rather esoteric subject that, it turns out, affects coach converters in several ways.


Sean, First off I'm not afraid of being wrong and am more than willing to admit a mistake. However, on the other hand I don't want you to feel like I'm beating you up by carrying on. The reason I said I'd like to drop it is not because I'm afraid of being wrong, but because a rather minor point is getting blown out of proportion. So with that out of the way, if you insist, let's get this hair split.

We are in agreement on almost everything, but what originally raised my eyebrow was your contention that the current drawn by a fan motor is being converted to heat, rather than work. You asserted that view again with the "black box" analogy and now you've underscored it with a restricted filter scenario.

Quote
 Blocking the fan's air flow, in fact, will not lower the current, but rather it will raise it as the fan struggles to move air against constraints.  Anyone who works with HVAC systems can tell you that the load on the fans increases as the filters become more restricted, for example.  But the point behind the black-box though experiment is not to equate a coach with the black box, but rather to illustrate that all the energy becomes heat -- true even if you take the black box away completely.  

My point is that a fan motor converts energy to actual work and not simply to heat. It's  a  misconception to think that a "choked" fan's  motor draws more current. (Until you can run an actual experiment to prove it to yourself, please humor me and play along.) In fact the exact opposite is true.  A fan with a restricted flow path draws less current, because it is doing less work. Less work because the electrical energy a fan motor draws is normally being converted to work, and not to heat.  A "choked" fan can not convert electrical energy to make any appreciable amount of heat, or to do its usual work, and thus the motor's current draw drops.

In summary, my minor, simple, concise point is that the portion of an electric unit heater's current draw which feeds the fan motor is NOT converted to heat energy, but to work, in the form of moving air. Yes, someday when the universe implodes maybe the fan's work will become heat again. In the meantime, with a real-world practical application I'll say that a typical fan motor located aboard a coach is not adding appreciably to the coach's heat load, (very minor inefficiency loses aside) while adding greatly to the interior's comfort level.

Ted
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« Reply #26 on: November 17, 2011, 05:14:33 AM »

Be aware that when heating your bus with an electric heater, it can get expensive. 

I broached this issue in this thread:

http://www.busconversions.com/bbs/index.php?topic=22056

My calculations suggest it cost me around $60 a month in the cold months.  In that thread, I suggest getting a thermally controlled outlet that will control a switch only electric heater so that it turns on at 35* and off at something like 45*. 

I did order the outlet, but have not hooked it up yet.  The electric heater that we have been using is thermostatically controlled and will not work with that outlet.  However, we have a unit that is a simple switch (on/off) and it should work fine.

Jim
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« Reply #27 on: November 17, 2011, 06:14:04 AM »

...
My point is that a fan motor converts energy to actual work and not simply to heat. ...
In summary, my minor, simple, concise point is that the portion of an electric unit heater's current draw which feeds the fan motor is NOT converted to heat energy, but to work, in the form of moving air.

Yes, this is correct ...

Quote
... Yes, someday when the universe implodes maybe the fan's work will become heat again....

... but this is the part that's wrong.

It's not "someday" a long time from now -- it is almost immediate.  Where do you think the joules of work are going?

Forget about moving air for a moment, and let's instead consider the work done to push a heavy box along the shop floor.  Whether you use an electric motor or you push it yourself, a certain amount of "work" is done to move the box.  The First Law says that that work can't just disappear, but when you stop pushing the box, where did it go?  The answer is every bit of it, 100%, was converted to heat by the friction of the box against the floor.

This is, in fact, where most work goes.  Now if, instead of moving it along the floor, you lifted the box onto a table, most of that work would have been converted to "potential energy," which is released when the box again moves from the table to the floor.  You could connect the box to a pulley and a generator and get some of the work back in the form of electricity.  But moving laterally along the floor, 100% becomes heat from friction.

Now back to the fan:  100% of the energy imparted to the air by the fan, which is work, becomes heat through friction.  Not "someday," but by the time the air stops moving.  What stops the air from moving is damping, and damping is friction, plain and simple.

Same is true for the toy train -- yes, the motor performs work, to move the train.  But when you turn off the power, the train stops almost immediately, and 100% of the work used to move the train immediately becomes heat.

So, ultimately, having some of the electricity go to a motor rather than a resistive load causes, at best, a slight delay -- on the order of seconds, or maybe at most a minute --in heating the interior, as the electricity is first converted to work, and then the work is converted back to heat.  But in a steady-state, that delay is irrelevant.  There is no getting around it -- in a closed system like the inside of a coach (or a house, or a computer room), absolutely every watt-hour that goes in becomes heat, unless it first comes out in some other form as I discussed originally.

-Sean
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« Last Edit: November 17, 2011, 06:21:08 AM by Sean » Logged

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« Reply #28 on: November 17, 2011, 05:47:37 PM »

Just to throw another thought out here on these infrared heaters.  I was foolish enough to buy one several years ago.  I agree that most of the claims the manufactures made are lies.  However, I loved sitting in front of the heater every morning before I got fully dressed and let the infrared heat absorb in my back and my knees.  It is my opinion that there might be something therapeutic about the infrared heat.  As for any other claims of these heaters they are bogus and certainly not worth 3-4 hundred dollars or so.

I happen to have a 1025 sq ft house and there is no way this heater could heat my house but the heat it did put out felt good.  Could it heat a bus?  Very likely.  However, not any better than any other $1500 watt heater... but the heat may feel better.
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« Reply #29 on: November 17, 2011, 06:31:13 PM »

It's never too late to pick nits on and on and on!
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