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Electric Heater Efficiency

J

John T

Well-known Member
AS a retired electrical engineer I enjoy the electrical discussions on here now n then n try to help with questions the best I can. Also, as an engineer YES I KNOW A WATT IS A WATT...... regardless if its consumed and converted to various other energy forms like say an electric motor (magnetic field and rotation) or light bulbs (light n heat) or a cheap wal mart electric heater (heat maybe a lil light) or an expensive Amish built or Eden pure heater (heat maybe a lil light) etc etc.......

BUTTTTTTTT MY QUESTIONS FOR FUN DISCUSSION ARE:

The reason is Im sure we would all agree (engineers n technicians n laymen alike)

1) If we consumed 1500 watts in a room by running a 2hp or so electric motor, since some of the energy goes to magnetic field and some to ROTATION, there would probably be less heat generated then if we ran a 1500 watt electric heater EVERYONE AGREE??????

2) Although EITHER would consume 1500 watts, if we burned 1500 watts worth of the higher efficient (more lumens/watt) CFL bulbs we would get more light (lumens) then if we burned 15 100 watt incansescent light bulbs EVERYONE AGREE????

3) SOOOOOOO just as CFL lighting is more efficient then incandescent (more lumens per watt),,,,,,,,,, and just as A 3 phase motor is more efficient then a single phase motor ,,,,,,, AND SURE A WATT IS A WATT AND EITHER OF THE ABOVE CONSUMES WATTS BUT DOES NOTTTTTTTTTTTTTTT YIELD THE SAME IN HEAT OR LIGHT, Id think a more efficient electric heater (more BTU's per watt) will yield more BTU's per watt then a less efficient electric heater..

Everyone agree??????????

4) Or do some think any electric heater (strip or quartz or infrared, Wal Mart or Eden Pure or Amish etc etc etc) ALLLLLLLLLLLLLLLLL have the same BTU per watt effiency????????????????

5) Does anyone have any hard data regarding the EFFICIENCY in BTU's per Watt of say wire strip heaters versus infrared versus quartz etc etc

CLOSING:

I think Question 5 is the key here so we need the actual hard data OF THE BTU'S OF HEAT GENERATED VERSUS WATTS CONSUMED for strip or quartz or infrared heaters etc etc UNLESS someone has data that ANY TYPE OF ELECTRIC HEATER yields the same amount of BTU per watt !!!!!!!!!

A THOUGHT: The inefficiency of a motor or light etc is that some of the energy is "wasted" in the form of heat losses versus light or rotation soooooooooooo if the inefficiency of an electric heater is due to some of the energy is wasted as HEAT welllllllllllllllllll there ya go anyyyyyyyy heater is the same ??? Hmmmmmm lol

Sorry so long, as an engineer now an attorney I cant help myself lol

God Bless yall n keep warm now ya hear REGARDLESS how efficient you do it

John T
 
Yes an actual BTU/Watt comparison is needed. I have not seen any of the edenpure heaters and such publish that though. Most other electric heaters seem to publish their BTU output though.

And yes I feel there are slight differences in efficiency of electric heaters. Ceramic vs glowing strip, etc... But from what I can find out the differences are minor.

Now some methods can feel more efficient depending on the environment. In a drafty place quartz radiant heaters sure feel more efficient :)
 
Have you seen any data or even a claim from the 'magic heater guys' that they can exceed the standard 3.41 BTU's of heat per Watt of electricity?

I've never seen any claim like that. They just wax warm and fuzzy, rainbows and unicorns, about their wonderful products.

(Not to mention the amish cabinets!)
 
1) No, if a motor is using 1500 w of resistive power, then it will create the same amount of heat as the heater, since you said the shaft is not hooked to anything.

2) Yes you get more lumens per watt from a CFL

3) CFL is more efficient at producing light. Depends how you define efficiency. 1500 watts of CFL's or old time bulbs heats a closed room the same since the light is converted to heat as well.

4) Electric heaters are always 100% efficient at producing heat, radiant heaters just might be the tiniest fraction less because they produce some visible light but in a room that is also converted to heat. There is NO difference other than that.

5) Sure I have some hard data, but it would be first year university physics or high school physics lab notebooks from experiments they make you do.

You can do them too. Get an insulated box, a watt meter and thermometer. Some basic calcs. All the same. Don't shine the radiant heater on the thermometer.


I think the problem is you are confusing radiant, convective and conductive heat transfer. Different heaters move heat in different percentages of each method and we sense them differently.
 
There is no difference in efficiency.

The difference is a radiant heater shines a beam of heat, like when you step out into the sun or look into a camp fire up close.

Convective heaters heat the air then you get the heat from the air, or more accurately, you stop losing heat as quickly to the air. In a drafty house the hot air is carried away before it reaches you.
 
Ken, I think the reason a motor appears less efficient as a heater is because of its heat capacity. It can store a great deal of thermal energy, so its temperature rise is less. That lower temperature is perceived as lower energy. The other problem is that the motor of course does not have a unity power factor, so it "appears" to consume more power that it actually does.
 
I am with Ken on this one. I have some of the same lab notes in the archives (deep in the archives). It is a relative simple first law of thermo application. Now you could get tricky and hook the motor up to something so that it is raising a load onto a shelf or somehow storing energy, but what you ultimately find is that all the energy entering the "control space" (i.e. room) is converted to heat in some form or another.

Ken is also correct when he states that our perception of different forms of heat transfer affects our comfort level. We don't really feel "Temperature" we actually feel "Rate of Heat Loss/Gain", thus the strange concept of "Wind Chill" (look back a few weeks for a discussion of this).

Looking forward to comments on this,

Kirk
 
My Amish neighbors are still looking for a place to plug in those Amish electric heaters ! LOL
 
Gotta love this conservation of energy stuff n heat transfer...... From Thermo about all I remember is Heat lost = heat gained..... I like the heated air talk n the reason we feel cold after stepping out of the shower is cuz the evaporating water off our body is carrying the heat away (ie we feel cold) the heat of vaporization...... Intuition still tends to tell a person just as some lights are more efficient the same ought to be true of heaters, but if allllllll the watts consumed get converted to heat energy one way or the other, HEY IT ALL COMES OUT THE SAME REGARDLESS IF A CHEAP WAL MART STRIP HEATER OR A QUARTZ INFRARED EDEN

This is just the fun type of discussion I (as a nerd lol) was lookin for

John T
 

Hey John T..

If a house is heated with a fuel-oil furnace, that oil, let's say gives off 1oo% of it's energy...
(I would think a diesel is more efficient than just burning fuel)..

Now, if we replace that oil furnace with a diesel engine turning an electric generator..and capture the heat from the entire diesel engine..AND the power from the Generator..what efficiency percentage are we looking at now..?
I know, there are always "losses", but I just can't see burning fuel and getting Nothing productive out of it..!!
We need to get together and produce a Heat-Power unit for home use..
Regulated and inspected, it would replace massive power-plants..even if they were only used in the winter...
What do you think..??
Ron.
 
Hey Ron, Im all for disconnecting from Mother utility n heating our own homes be it solar or wood or fuel oil or whatever butttttttt those darn economic realities grrrrrrrrr Can we buy oil n heat cheaper then electricity?????? Can we buy LP gas n heat cheaper?????? Can we buy natural gas n heat cheaper????? Or wood if we buy it or cut our own??????

Like I used to tell my kids when they were in high school science ALLLLLLL HEAT IS FROM SOLAR HEAT..... It (the sun) grew trees that rotted n became coal,,,,, it (the sun) grows tree for wood heat,,,,,,it was rotting grown by the sun "stuff" that became crude oil or natural gas.....

I also told them there was no such thing as COLD, ONLY THE ABSENCE OF HEAT...look in the sky theres the sun NOT ANY ICE CUBE LOL Were NOT Cold we just arent exposed to sufficient heat

Love this physics n stuff

John T
 
Thats what I was getting at with the mention of resistive power. An unloaded motor has a terrible power factor.

A high mass heater like those oil filled electrics take a long time to heat up and cool off but they still have the same efficiency when in steady state.
 
Your talking CHP or combined heat and power. Japan has a few of these. Some folks here have them too. The generator runs to charge batteries. The waste heat heats their house. Overall efficiency very high.

In the USSR instead of dumping waste heat from power plant condensers into a large body of water it was sent out into a district heating loops to heat people houses. Incredibly efficient use of low grade waste heat!
 
Yea, it is kind of fun. Had an Architect client of mine ask a few weeks ago about the Edenpure heaters. Basically told him the same thing "all the watts end up as heat regardless of what box they come from".

Have a good day, always like your dissertations on grounding, generator hookups, real estate matters, estates, etc. I used to think about heading to law school, but don't think I have the desire anymore.

Kirk
 
Are you saying the Amish and Edenpure are not what they are claimed to be or are they godsent?
 
The Amish around here have propane piping, about a foot down, run around their ceiling. Has lantern mantels every few feet, used for heat and light.
 
Now dont forget,an electric motor does not run on electricity,it runs on pre installed smoke.
If the smoke escapes, the motor is kaput. So no more heat.

steveormary
 
As long as you are talking about efficiency, what about magnets? I still say a permanent magnet has a power of it's own. A starter with permanent magnet fields will draw less wattage than a wound field starter and turn the engine the same. The same with heater motors. What is your opinion on this?
 
http://www.hydrodynamics.com/product_pics.htm

http://www.infinite-energy.com/iemagazine/issue31/deviceupdate.html


http://www.overunity.com/index.php/topic,356.0.html


http://www.physicsforums.com/showthread.php?t=14630
 
John T, Even though physics would be my main credential, in order to provide an answer to any of your questions, a retainer would be due in advance. On a less serious note, here is another question to add to your list: If your containers are of identical size, R factor, eternal environments, with an incandescent light as the heat source and everything else is equal, except, one container has a window that allows light to escape, does the one without the window rise to a higher temp? If so does this relate to E=mc2?
 
Magnetic lines of force are no different than the force of a post holding a roof up. If it doesn't move it doesn't perform work or have power.
PM motors #1 don't waste electricity making magnetic lines of force by pushing electricity through windings.
#2 PM motors have a shorter current path which lowers the internal resistance. Less resistance = more current which equals more power if the voltage stays the same.
Reading posts of this nature makes me wonder how students pass tests and exams in school on the most basic questions in physics? And, what are they teaching in school?
 
Don't bank with those guys! They recently concluded that an airplane could take off in a shorter distance if it was on a tread mill (a moving tarp under it's wheels). :?:
 
If ONLY we could capture all the HOT AIR this thread has generated, we could heat anything we wanted and not worry about efficiency. LOL. Might have to worry about global warming ? NOT.
 
E=MC2 deals with nuclear physics./reactions. Magnetism is a wholely different but related force.
Electricity and chemistry deals with the (-) electrons circling the (+) nucleus.
A 1500W resistance heater gives off 1500W or 5115 BTU. No more, no less.
The only way to “gain” is to use a heat pump to “move thermal energy”.
These Amish heaters are some of the most refined snake oil I have ever seen.
A 1HP single phase motor drawing 12 amps at 120V. Puts approx 746 watts of power on the shaft, 360W of waste heat blown out the cooling grill. And circulates about 3 amps as reactive power which does no work but heats the wires/windings.
Reactive power is also why small portable generators which “appear to be just large enough”. Won’t run the intended motor, welder etc.
 
I think Ken Macfarlane Is on the money. The gag response to the Amish Mantle garbage is keeping me choked up. A radiant watt radiated into a room has a feel good factor that fakes a person into the belief that the room is warm, when they just absorb EM radiation (infared). But the watts are still there. Savings could only accumulate in a underutilized facility when temporary occupancy was desired and a radiant heater used to keep the temporary occupant warmish, then shut off. Imagine the sticker shock if those heaters were to ba placed and run in every room until the ambient (read thermal temperature) of the contents and walls were stabilized at the desired temp. As someone on here indicated, the electric meter could be heard spinning like a jet turbo. JimN
 
I dunno, I had one that released the magic smoke. Then later when I tried to run it again, it put out A LOT of heat and it released bonus sound energy to boot. I guess there was just enough magic smoke left in there.
 
If your point is that these high end electric heaters are more hype and marketing than performance you are right.
 
What's the control volume and how are you defining "efficiency"? If the heater unit itself is the control volume and if the efficiency is defined as the heat output of the device (i.e. the heater) divided by the energy supplied from the electrical outlet, then the efficiency will not be 100% due to line losses between the heater connection and the outlet. But it will be close. A motor driven fan complicates the issue but certainly will make the entire process less efficient. The 2nd Law of Thermo says we can't even break even so I doubt that even a pure resistor is 100% efficent in coverting electrical power to heat but I am at a loss to explain the mechanism for the that loss. I'm an engineer not a physicist.
 
Simple. Everything thing we do with electric energy turns to heat. Whether its a high efficiency or low efficiency lamp the only difference is the spectrum the energy leaves the lamp. Blue light carries the same BTUs as IR light. And all that we put into motors that doesn't come out as heat comes out as heat from friction in whatever the motor drives. It may not be as hot a heat, but all the energy ends up as radiated or conducted heat. No difference for gas, diesel, natural gas, or steam engines.

All the energy we put into tractors, cars, trucks, and airplanes as well as in lighting and building heat leaks to the atmosphere as heat. A lot has to go through friction but it all gets to be heat applied to the atmosphere.

Another engineeer figured a few years ago that all that energy that goes to the atmosphere (all that we create by power plants, burning fuels, and EATING and living) is more effective at raising the climate temperature than all the CO2 holds in from reflecting the radiant heat leaving. At the same time upper air CO2 (or water vapor which is more effective) reflects heat back to the surface, it also reflects solar heat out to space. In the end it balances out, we don't have much affect on climate.

Gerald J.
 
I didn't have time to read all the responses below. There is probably some good comments & discussion.

The answer depends on how you define efficiency. If you define efficiency has the amount of heat dissipated, divided by the electric energy consumed, then all the devices have 100% efficiency, even the motor, as long as it is not connected to some load that is storing energy (such as pumping water or compressing air). If you define efficiency as the amount of heat delivered to your skin, where your body temperature sensors are located, divided by the electric energy consumed, then there can be quite a difference.

I am a practicing engineer and design generators for electric power plants. Efficiency is critical to us (how to improve it, how to measure it). Some interesting facts (perhaps): Most large generators are better than 99% efficient. One tenth of one percent gain in efficiency in a large generator is worth about 4-5 thousand dollars per day, or about 4-5 million dollars over the typical life of a generator. But, a loss in reliability to gain that extra efficiency that results in a repair of more than a couple days wipes out the entire savings.

RND
 
John, you bad boy! Trying to trick folks with your bogus clues. As someone who passed his PE back during the Crimean War, you know good and well that every kilowatt-hour you pump into a closed system gets turned into heat, one way or another.

If you think of your house as a closed box with a couple of terminals attached, it turns into one big resistor. (For the purposes of our argument, I'll say your house has no windows so no light escapes.) It doesn't matter what's actually inside (assuming there are no energy storage devices, such as batteries), all the energy applied via your meter ends up as heat.The only difference is the method of energy conversion. It may go directly to heat, or it may take a different path, e.g. first to light, then heat as the walls are warmed by the light. You might be powering radios, TVs, quartz heaters or even "Old Sparky"; it all turns into heat in the end.

I've been researching the effectiveness of using my table saw to heat my shop. I can tell you it does a lousy job: not only does it not put out enough heat to keep me warm, it generates a lot of sawdust and noise in the process. I've decided to let my wife keep her electric heater and I'll leave the saw in the shop.

Now that said, certainly there are some heaters that do a better job of keeping you warm than others, even though they all are converting electricity to heat with 100 percent efficiency. Radiant heaters that warm objects rather than the air around them use less energy to heat those objects. It's not the efficiency of heat [i:654c4848f0]generation[/i:654c4848f0], but rather the efficiency of heat [i:654c4848f0]transfer[/i:654c4848f0].
 
What's to say that everything taught in school is 100 % right? It takes a curious and questioning mind to make changes and new inventions.
 
I have used small portable 1500w resistive space heaters since 1964. I have found that while they
work well for my application, the twelve that I have owned have required a lot of repairs. I believe that they all need upgraded to
a minimum of a 14 gauge power cord.

I have attended 3 recent sales of eden pure type heaters.

The positives I have seen are that they all have had heavier cords, better quality heater thermostat controls, higher volume fans, and seem to be less likely to directly cause a fire than my $19-$39 heaters.
The negatives I have seen are that they cost a lot more-$450-$700, questionable effiency claims, and they take up more space.

The EP type heaters all seem to use quartz glass
resistance tubes to heat a copper heat exchanger tube that air is forced through to provide convection heat. I suspect that changing from radiant to convection heat loses efficiency.

They look to me as though they may be a relatively safe, high quality source of heat if they fit into your budget.
 
You say " If it doesn't move it doesn't perform work or have power". Lets say you have a scale with a hanging basket. You put a permanent magnet in the basket, then put a 10 # weight of iron UNDER the basket and it stays there defieing gravity. The scale shows it is holding up 10#. Even though nothing is moving,there is a force that is holding it up there. And God only knows how long it may stay there. If you held that same weight up at arms length, even though you didn't move it, you would get tired pretty soon. Right? So I still say a permanent magnet has a power or force of it's own. That power comes from the atoms of the material(matter in motion) according to E= MC squared.
 
Sorry. There are some basic laws of physics you have overlooked.
A post holding a roof up is under stress/pressure. However it is not doing work or expending energy.
Power = Force X distance /time. No distance means you are multiplying by zero which makes the results = no work.
Do you know what E=MC2 means ?

Are you not the same dude who believes in perpetual motion machines?
 
one more thing, the so-called "Amish" heaters are not made by Amish, only the wooden cabinets they are mounted in are. as I understand, the heaters are made by the same company that makes the Eden Pure heaters.
 
Teddy, the definition work is force applied through a distance. And the definition of power is work performed at a rate. If you say that a magnet holding something in a stationary position constitutes "power", all you've done is to redefine the word "power" and by extension redefined "work". And since "work" is just another word for "energy", you've also redefined "energy".

The problem with redefining a word is that it doesn't change the underlying principles. So you can say that work, power and energy are something different, but that doesn't make them useful. You can't use your redefined energy to heat your home, move your car or operate your cell phone.

Surely anyone who throws "E=mc<sup>2</sup>" around knows all this.
 

What I was trying to get at was, the new furnaces are rated at near 97% combustion efficiency...

OK...then what efficiency percentage would you have with the Diesel/generator heating unit...?

I think of it as.. If I start my car and let it set and idle all day and burn up a tank of gas, it may have burned it "efficiently", but it didn't "DO" a darned thing in the process...!!!

Am I comparing apples to oranges....?

Did you hear about the guy with no power who used his Hybrid car, with an inverter to power his freezer, refrigerator and some lights (maybe more) for 3 days with it..?
He claimed the motor only ran 5 minutes every hour or so...great idea..!

Ron.
 
The only reason some people like this type of heater is: Heat produced is at a LOWER Temperature and does not change raphidly up and down. A watt is a watt and residential Electric meters measure WATTS & bill accordingly. If the heat is at a lower TEMP. it will not rise in the room as fast making you FEEL warmer longer before it is disapated ! REMBEMBER the basic rules of Physics: Energy (heat) can not be created or destroyed, only changes state. Heat is a commodity (BTU, watts, Joules). How it is transmitted by: convection,conduction,& radiation and it all costs the same if measured by your electric kilowatt hour meter. Do watt feels best!
 
The Amish dont like to be photographed,Plus the fellows handle a hammer like they have never used one before.Bunch of actors making a tv ad.
 
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