Energy Consumption Comparison of Electric Space Heaters

A 1 Kw electric heater will consume AND dissipate 1 Kw of heat.

From thereon it is a matter of details, packaging, esthetics, and hype. Some radiatee and/or promote convection better than others. The more advertising and the higher priced units are not all that they would have you to believe,

One of the cardinal principles in all of engineering addresses the quesiton. Conversion of electricity to heat by resistive means is 100.000% efficient. If a travelling salesman knocks on your door and offers to sell you an electric heater which produces twice the heat as others with the same power consumption as competing units, you know immediately that he is lying.

There may be a possibility that fans in some heaters are better than others, circulating air within the room to a greater extent, but the heat output (average temperature rise vs. power consumption will ALWAYS be the same unless some deceptive "trick" is used. Moreover, it is more difficult to raise temperatures at outside walls due to thermal resistance of the wall, and lower temperatures on the outside.

An old engineering question is: Suppose a refrigerator is located in a sealed, insulated room. The refrigerator door is left open. Will the room temperature rise, fall, or remain the same? The temperature will rise. If anyone does not understand the reason, I will post it.

Berniek

Berniek is 100 % correct on the heaters, and also the refrigerator in the room ... (assuming the refrigeratore is running of course).

These advertisements of electric heaters have annoyed me. Most of them are drastically overpriced.

However I would just like to add that while all electric resistance heaters are 100% efficient, there are subtle and not so subtle differences in how we sense their heat.

For one thing, exposed resistance wires that glow red hot will make you feel warmer than the ambient air temperature would by virtue of radiant heat if you are in front of them. However the side away from the heater will feel cooler. In other words the sensed heat is very uneven, but this may be fine in some circumstances. High or lower temperature heating elements, combined with a fan, heat the air much better but also suffer to some extent from the fact that how you sense the heat may still depend on where you are in the room in relation to the heater and whether the air is blowing on you or not. Again, they may also be fine in many circumstances.

My personal preference, for heating a "living space" with a portable electric heater are the oil filled or water-antifreeze filled radiator type. They are silent, create no breezes, and the sensed heat is very even (assuming of course that the room is not drafty from external air entering). These heaters are very reasonably priced with good 1500 watt units costing typically under $50.

Advertising claims have to be read skeptically and with attention paid to the fine print. Claims for savings typically mention somewhere that by using their heater, you can lower the heat in the rooms not being used: and this is the source of their claimed savings, despite the fact that they imply that it is because they use some "breakthrough" technology that is more efficient.

Claims of their heater not drying the air which some make are equally spurious. When you heat air, the relative humidity decreases .. period. The only exceptions would be actually adding water to the air as it is heated, (like boiling an open pot of water) or, an unvented combustion heater which adds the water produced as a byproduct of combustion however this is dangerous and can actually kill you. There is however one issue that deserves mention and that is that heaters with very hot surfaces such as bare resistance wire electric heaters, can "singe" the dust particles in the air and make the air seem dryer and more irritating than the actual relative humidity reading. (Another reason I like the oil filled radiator type.)

To conclude, all electric heaters convert electrical energy to heat at 100% efficiency, and all this heat ends up in the room! Pick the type based on your need and preference. For instance to heat a work area in a large open space, radiant is probably best if you can not heat the whole area. If you have to heat a place intermittently, like a garage, then a heater with a fan is a good bet. For living space, the radiator/convector type shines, but the choice is yours to make. Just don't be taken in by those misleading claims.

Thanks, Greg... I've been wondering about eden's claim... yet, while skeptic, I still did not know if it would be a sound investment... your post put the final nail on gen4!

I would venture that Stirlings post already takes into account that Mkel already knows that heat by conversion from electricity is inherently inefficient due to waste of energy--and consumer dollars--transmitting electricity to the conversion appliance. However appealing the 100% conversion efficiency (after that loss) might be--as a way to cut through puffed up claims and hearfelt opinions--it misses an essential point. In addition to conversion efficiency, per se, must be taken into account that all electric space heater types--save one--heat only a relatively small fraction of the air that passes over or through them, whether actively or passively. The oil-filled convection heaters of which Mikel speaks have gained considerable market presence, and much favorable (but undeserved) consumer opinion largely on the basis of skillfull (albeit inaccurate, even deceptive) marketing/package advertising by their purveyors--primarily De Longhi. Their appeal to American consumer gullibility with the references to European consumers also seems to have been quite effective; but they do not advise American consumers of the difference in heating requirements faced by those Europeans, which can be quite different from those across the pond. The oil-filled heaters can be useful, even adequate in some situations, but only under limited conditions: small spaces needing heat; use in combination with whole house space heating; they only reach best (air heating) efficiency--which is not that good--after the space is already warmed. Apart from these, the oil filled heaters are among the poorest performng (and least economical) for typical space heating needs--especially when their comparitively high purchase prices are taken into account. Even so, it could not be said--until the eighties--that any other type of electric space heater performed much better, and some did perform worse. This changed in the eighties with the advent of the thermistor controlled ceramic disc heater, the same which were quite expensive then but but are priced far less today--and are even cheaper than most if not all competitor products--including the DeLonghi oil filled--when their inarguably better performance and operating cost efficiency is taken into account.

The performance edge of the ceramic heater had its origin with a simple idea: to start with the the best performing free-standing, gas fired space heaters--the ceramic gas fired heaters (e.g., Dearborne) and build on that. Passing of filtered air through ceramic heating elements achieved something no other resistive element heater could approach doing: to heat 100% of all the air that was drawn through it. Because of this, the ceramic electric heater produces maximum heat immediately upon activation--it does not rely on preheating of the air to come to full heat output as do all other electric space heaters. Because of the high heat retention of the ceramic elements (discs) the problem inherent in other electric heaters of noticeably large temperature swings during thermostat cycling is also avoided. In regard to latent heat retention the oil filled heaters attempt to achieve a similar end; however, much energy (and electric power $$) is lost simply bringing oil and tank of oil-filled heaters to a point where usable heat can be radiated: energy that does little or nothing to heat the surrounding space, and which is largely forfeited during thermostat cycling. The ceramic disc heaters are so efficient at heating air that the motor is needed not only to draw fresh air through it, but also to regulate the maximum temps of the discs themselves. Finally, the ceramic heater is able to also achieve an efficiency unique to itself: because it is continuously controlled by temperature sensing thermistor, no more energy than is required to maintain a set room temperature is ever expended, whether it be energy converted to heat, or energy used to power the fan motor. As the space begins to heat (and quite rapidly compared with the oil fired heater especially) the element power, and fan speed and air flow through the heater are gradually reduced...eventually to a point where the heater runs at a power level only a fraction of its rated maximum. Unlike thermostatically controlled oil-filled heaters, no energy is wasted either letting the heated space cool enough for the thermostat to make contact, or overheating the space in order for the thermostat to break contact.

Since it would be difficult to really know who makes any heater nowadays, it would be difficult also to refer Mikel to a source of comparative information. But it might prove useful to search for "Pelonis," which was the original patent holder and manufacturer of the ceramic electric heater. When the product first came on the market that company provided considerable technical info about its heater in comparison with competitor heater types. Whether this is still true today--or whether the Pelonis brand still still exists (except in name only on another manufacturer's product) I am unable to say--because the Pelonis heaters I purchase when the product first came on the market is still functioning just as it did new 20 years ago.

With due respect to "Guest", poster #4, all of the energy fed to an electric heater is converted to heat, EXACTLY 100%. It does not matter if the resistance wire windings are free standing or wound on ceramic. It does not matter of all of the air going through the heater is heated. If some of the air is not heated (if it bypasses the heating element), the air which does become heated is raised to a higher temperature than expected.

We all know that fossil fuel power plants have an efficiency of about 40%. That is not the question here. The question posed by Striling addresses heater efficiency one the elecricity is considered WITHIN THE HOUSE. If a given heater draws 10 amps at 115V, the heat output will be 1150 watts, no more, no less, due to the law of conservation of energy.

Although a glowing heating element may make an occupant feel warmer when in the proximity of the heater, the principal in that case is one of heat transfer mechanism, radiation in this example, which varies as the fourth power of temperature difference. Heaters with fans will heat air directly by conduction rather than radiation. Whether by convection, conduction or radiation, heat transfer from the heater to the room will provide exactly 100% of the incoming electrical power, less a few watts for fan power consumption if one is used.

Berniek

With equal respect, it appears that para. 2 and 3 of the reply are superfluous: careful reading of guest #4 post would have revealed (1) the presumed agreement that power plant losses and transmission losses between plant and appliance were implicitly discounted by the manner of the original questioner's post; and (2) that, in similar vein, the question of sensible temperature was not even mentioned--it being likewise extraneous to the question originally posed.

Likewise, no issue was taken with the assertion regarding EXACT energy conversion ratios; only with the implied statement, that because of the theoretical efficiency of electric to heat conversion, all heaters of equivalent power input could be judged as being equally efficient (equally effective for thread leader's purposes) at warming a given space--and the second implicit assertion: that there is no point to discussion starter's request for information by which to compare heater types. Please consider the following excerpt which possibly will explain....better than I was able.

Q: Aren't all 1500 watt heaters the same since they generate the same amount of power? What makes PELONIS ceramic heating appliances so unique?
A: If it were only a question of watts, then any electrical appliance that generates heat can be used to heat a desired area. Your toaster or clothes iron may also be rated 1500 watts but you don't use them as heating appliances because they can't transfer that heat effectively. The same can be said of electrical heating appliances that use different kinds of heating elements. Although they might have the same wattage rating, some have better heat transfer capabilities than others. Heat transfer efficiency makes PELONIS products very effective, especially those with the Honeycomb Ceramic Disc heating system, because they deliver the hottest airflow. In many instances, the airflow can get over 100 degrees Fahrenheit hotter than coil element heaters.

For further information, here's more info:

http://www.pelonis.com/faq.htm

There are numerous other resources as well.

As to any opinion expressed regarding oil filled "radiator style" electric heaters (and other kinds as well) my assertions were base also on direct experience with (and general dissatisfaction with) that kind of heater as a primary space heating appliance. In fact, I have one slightly used one, and three never used since new because the first simply cost too much to operate only to have a slightly warmed room within any reasonable span of time. For me it was cheaper to forfeit the investment than continue using them. Maybe one day I'll put them on sale, since I see so many folks willing to pay too much to buy them because they are wow-ed by the fancy manipulations on the cartons in the stores. Anyhow, thank you for your reply to my post.

Guest #8-5-4

I agree to this statement, if you put the same capacity of heater to similar room it will basically draw the same result. however, manufacturers has always little secret on their trade.

"however, manufacturers has always little secret on their trade."

Which means exactly what ????? They secretly defy the laws of physics?

"I agree to this statement, if you put the same capacity of heater to similar room it will basically draw the same result."

And what do you imply by the word "basically"?

First you say you agree, then you go off and say you don't, offering nothing to support anything you say.

no sir, the secret is on materials of those components, how they made it and who made it. there is no such thing as perfect engineering but now a days technology advancement using what you called laws of physics as a tools does not gave you the assurance that your work and other peoples work are the same. if we confine our selves to what you perceive as defying such law technology will never evolved. PEACE

In reply to Guest #4 (and his subsequent postings): Rubbish!

He is guilty of promoting the misleading advertising I am complaining about. His posts are full of mistatements, and contradictions.

First, he violates laws of physics and contradicts himself by saying that the ceramic heaters provide full heat instantly, then follows it by saying they retain heat: which is it?

Whether a heater has high thermal mass such as cast iron radiators, oil filled radiators etc or low thermal mass such as open wire resistance heaters or modern hydronic baseboard units is not the issue: All the heat ends up in the room! Temperature swings are almost entirely the result of thermostat sensitivity, location and design (some mechanical thermostats used in conjunction with high thermal mass systems have small internal heaters to turn them off slightly before the air temperature reaches its set value to take into account that the radiators would continue to heat the air for some time after the heat source was removed. On central heating systems this feature was typically adjustable and referred to commonly as the "heat anticipator" setting.) To imply that the heat stored in an oil filled radiator is somehow "wasted is ridiculous beyond belief. Incidentally, the word "latent" has no use in this context: there is no latent heat (" heat involved in a phase transition without a change in temperature") in any of the electric units under discussion.

As to the posting where he contends "some have better heat transfer capabilities than others" he is implying that the law of conservation of energy doesn't apply. What does he think happens to the heat that by his implication "is not transferred"?

Regarding his statement that oil filled radiators or other heaters are not suitable unless the room is somewhat warmed already is also ridiculous, having only to do with the heat requirements of the space, and the available wattage to heat it. All the electricity consumed ends up as heat in the room. His concept of it being "transferred" or "less efficiently transferred" is fundamentally flawed. That is of course unless the heat produced but not transferred to the room ends up in some other dimension (I'm joking).

There is nothing inherently wrong with ceramic heaters, they are typically quite good. The one he describes is excellent. However the selection of one type of electric heater over another is most largely a matter of personal preference, price and specific application. My personal experience, for my needs causes me to prefer the oil filled type, his causes him to prefer the ceramic type he described ... that is only our own preferences: neither is more efficient. The original post asked about relative efficiency, and that point has been addressed here amply.

In reply to Guest #4 (and his subsequent postings): Rubbish!

Proof by Britishism! What more do we need to convince....not only that the guest was full of it, but that the original post-er's question had nothing to do with judging the practical effectiveness of various heater types, but was posted only as a pointless academic exercise regarding electric-to-heat conversion efficiency. Can we now have a "balderdash"?

Okay, I had the same question/concern as the original post. So the bottom line is 1500 WATTS OF ELECTRICITY IN = 1500 WATTS OF HEAT OUT, REGARDLESS OF UNIT (OIL-FILLED RADIATOR, FORCED-AIR CERAMIC, HAIRDRYER, &c). I use both types, depending on need.

The issue that "Guest 4" muddles is that ceramic heaters provide nearly instantaneous heat, but when turned off, cool quickly; oil-filled radiators take longer to heat up, but, when turned off, they stay warm longer. Thus, all-in-all, the same BTU's. Thanks all members for clearing the efficiency question up for me. A more expensive 1500w heater (radiator, ceramic, whatever) doesn't heat any better than a cheaper one.

The main issues one needs to think about are:

• quietness (radiator being silent; there are relatively quiet ceramic heaters now as well, but most have fairly noisy fans)
  
• heating speed & heating continuity (if you want fast heat or steady heat)
• whether unit will have enough power to heat given area
  
• safety (particularly temperature of heating element; wire being the most dangerous since it can ignite paper, fabric, &c.)

Again, thanks for clearing this up for a non-electrical/physics kind of guy.

- Charlie

Philadelphia, PA

Good Summary!

The one thing I would add:

If one or more persons work mostly in one place (eg. seated at a desk or workbench), Radiant heaters (and to some extent others) can be aimed appropriately to warm only the person(s) and their immediate surroundings, rather than heating the entire room. In a large workplace or home, this can save considerable energy. This may be especially true if individual heaters are placed for individual persons, whose comfort levels may vary considerably.

Dick

I just looked at my clock.....MERRY CHRISTMAS......1 KW = 3413 BTU. Heat is transmitted in three major ways. By Radiation, Convection and Conduction. Electric heaters use any one or all three ways in producing heat. The radiator is popular because the heat is transmitted primarily via convection.Examining the surfaces of the radiator will reveal a large radiating surface. The oil, or possible other fluids, simply slows the rate of convection which in turn produces a more even heat. Radiant heaters are primarily spot heaters. It heats what it "sees". An example of conduction heat would be your water heater.

Most portable electric space heaters are rated 1450 to 1500 Watts. This rating is based on the "Electric Code" requirements Example would be a standard electrical circuit which would be rated at 20 amps, and that circuit would contain a maximum of 6 convenience outlets (wall plugs). Code says do not exceed 80% capacity, or 16 amps.A lot of residential wiring systems use 15 amp circuits, which means 12 amp max. With 12 amp max and 120 volt circuit, max allowable watts would be 12 X 120 = 1440 watts. If your space heating load is say 7000 BTU, then you will need 2 KW (7000/3413 = 2.05 KW) to heat the space. Using portable space heaters, you would need 2 heaters, and they MUST be on different circuits. Both on the same circuit would trip the breaker. By wiring a special and designated circuit, for a 30 amp load which requires 30 amp rated receptacles, a 2 KW heater could be used.........OOPS........I hear Santa Claus.

Just got back from letting Santa Claus in.....................

Clarifying the radiating surface of the radiator. Radiator is sort of a misnomer, it is a combination, radiator and convector. The amount of radiation iis actually rather low. The main heat output of the radiator is by convection. Radiators placed under an outside window stops the downdraft of cold air, warming it instead. With that air rising, it is replaced by cooler air, drawn from the floor, all at a low velocity, which creates a rather even heat throughout the space.

While conversion of electricity to heat is 100%, the generation of the electricity is not efficient, especially using coal fired equipment.....But that's an entirely different subject, ani't it?...........

While they don't strictly come under the category of space heaters I thought it was still worth mentioning reverse cycle air conditioners.

While it is true that with any form of resistance heater 100% of the consumed energy is turned into heat with reverse cycle air conditioners you can achieve efficiencies in excess of 100%. This isn't magic and no we aren't defying the law of conservation of energy. A reverse cycle air conditioner uses the electrical energy to transfer heat from a cold environment to a warmer environment and depending on the temperature differential the amount of energy consumed to transfer this heat energy can be less than the amount of energy transferred. It's exactly the same process that causes the condenser coil at the back of the refrigerator to get hot. If you compare the amount of energy used by the compressor it will in most cases be less than the heat output of the condenser coil. Think of the experiment wilt the closed room and the refrigerator with the door left open except this time the cold part of the refrigerator is outside the closed room.

"A lot of residential wiring systems use 15 amp circuits, which means 12 amp max. With 12 amp max and 120 volt circuit, max allowable watts would be 12 X 120 = 1440 watts."

This is a problem that we don't have in Australia since the residential single phase supply voltage is 240V so we can get 2.4 kw out of any power outlet no problems. We also can get 415 V between phases for super heavy loads like ovens etc. Doubling the supply voltage also reduces any loss in the cables by 75%.

One final point is that with electrical heating systems you get all of the consumed power as heat with no wastage. With combustion heating systems there are always losses up the flu etc. In theory this would make electrical heating more efficient but unfortunately most power is generated by burning fossil fuels so when you take into account the losses in the transmission you end up worse of than if you burnt the fuel directly where you wanted the heat.

If the electricity that you use is generated from some sustainable source and you can afford the capital expenditure, then the most efficient least polluting form of heating is reverse cycle air conditioning. It also has the added benefit of being able to cool you when you are hot.

The only observation that I could make is that the heating coil would be 100% efficient in all cases. The only further impact to efficiency might be that of the fan motor if a fan motor exist. But any lack of efficiency here would be converted to heat as it always is with any motor, and therefore represents no loss of electrical efficiency at all when compared to final and total heat output.

It's kind of similar to using motors that have eddy current clutches. They do poorly as far as electricity consumed to the final horsepower output, but they make good heaters!

Ing. Robert Forbus

Electricity to heat, what a waste, there are so many other fuels to generate heat why would one use flowing electrons to create heat? We as a species burn billions of tons of material to create electricity, it is far to valuable to run through a resistor to return it to heat. besides rember the law of diminishing returns?

One good way to use electricity for electric heat is through infrared. With enough infrared, the temperature in the room can be kept several degrees lower than otherwise comfortable so long as the room occupant stays in the heat rays. I suspect that with a good infrared source, the effective efficiency of the electric heat could be as much as doubled.

I used to see a heater type in the hardware store comprised of an infrared emitter mounted at the focal point of a reflective parabolic dish. The dish was mounted on a tripod stand and its position was adjustable.

To the best of my knowlege, the term "infrared emmiter" is nothing more than a pile of marketing horse biscuits. A "infrared emmiter" is ANYTHING which emmits heat... incuding my wife who helps me keep warm at night.

Nah, I thought of the term to explain the device I saw in the store. It was basically a high power heat lamp whose filament operated at a lower temperature, but had much more surface area than one in a heat lamp bulb. However, it was much more focused than a standard infrared heater.

I wonder if a giant array of infrared LEDs, about 10000 in number, would be optimal. It might feel like being out in the bright sun without the blinding visible light.

Oh! I just gotta reply to this. I have recently been doing research in high intensity LEDs. They are approximately 60% efficient. So where does the other 40% go??? It is dissipated as heat... which is what we are after in the first place. So hypothetically, a giant array of infrared LEDs would work. It would be horribly expensive though. Those critters aint cheap.

Bill

Hi Bill. I thought about the cost as a problem--true there. But it would be best if the efficiency were 100%. Then the all energy would be converted to infrared light energy, from which the misunderstanding arises. It is also known as radiant energy. It is light. It only gets transformed to heat when it strikes something with mass. If the efficiency of the infrared emitter (radiator) is 100%, the heating effect is most direct.

The frequency of the infrared is key. Apparently, if the frequency is too low, the rays are absorbed by the air before reaching the item to be warmed. Most electric heaters work that way, which is not always bad, though.

All electric heaters transfer 100% of the electric energy to heat. Thats a given.

Oil filled heaters I personally like due to the "safe" temperatures for touch and inflammability of materials touching them.

Ceramic heaters can cause fires, especially if they get plugged with wood dust, dust bunnies, etc, or melt plastics and materials that are too close. (from personal experience, Bird feathers and dust burn VERY quickly, plastic clothes hampers melt)

To muddy the waters of the thread consider other technologies:

For better energy "transfer" heat pumps (example: window air conditioners) are more efficient, but they are not "portable". The principle is that you can use 1 joule of energy to transfer maybe 2 joules of "heat" from one side of a wall to the other. Efficiencies depend on thermal gradients etc. There are some rather efficient heat pumps that work well in moderate climates. They are not well suited to cold climates unless you can draw heat from ground water or some other geothermal source.

Gentlemen of CR4,

with regard to the inaccurate claims of a "Guest" earlier (it happens sadly very often), please do not forget that sadly, some of the "Guest-logins" are people who either have "vested interests" in missleading CR4 members and other readers, or are simply people who have not the foggiest idea of what they are talking about!

To that end they hide behind a "Guest" login instead of joining CR4 properly and becoming identifiable!

Naturally, some of the comments are so ludicrous, that I have to laugh, which is good for us all anyway!!! Such were the comments in this article.

But basically I find it simpler to completely ignore/disrergard most Guest comments for those reasons........but it does show the "darker" side of the coin so to say as a comparison from time to time!

Happy New Year to everyone from me here in Germany.

Long may CR4 Reign!!!

Well Said, Andy!

ANDY..........Whut's rite fer yew mite not be rite fer me......and versa visa.......In my 20 years of official retiremernt, I've seen a lot of things change, even people's minds.....and it took me a few months to figure out how to log into CR4 as a member. (I'm still learning 'computor'), until I did, I logged on as a guest........and I'm all for free speech, expression, opinions, thinking etc., right or wrong..and I suspect you really are too...Hope you had a good Christmas and HAPPY NEW YEAR TO YOU AND EVERYONE ON CR4.......

G SCOTT

This is a reply to Andy in Germany, concerning those who have not the foggiest idea of what they are talking about.

There are some individuals who unfortunately do not possess a good grounding in physics, one of the major cornerstones upon which every engineering discipline is based. Certainly we can say that Newton had matters of motional and other aspects of physics right, until Einstein did his first publishing in 1906 (?). However, until proven otherwise, concepts such as the conservation law of mass and energy are our cornerstones to work with, and if we truly wish to be engaged in engineering, physical laws which have withstood the test of time are considered to be immutable in our time frame. Despite Einstein's relativity work, Newtonian physics remains the viable in more than 99.9% of real-world problems and needs.

There occasionally arise questions by non-engineers, e.g: If you have a room lined with mirrors, why cannot a flashlight be shined into the room, to produce lasting, brilliant light?

One of my favorites is the following: Two equal value capacitors are connected with a switch. One is charged to 10V, while the other is not charged. When the switch is closed, what is the final voltage across the (then) parallel connected pair? If you answer "5 volts", you are correct, due to conservation of charge, Q=C * V (the capacitance doubles, so the voltage halves to maintain the same charge). This is a dual of conservation of momentum in mechanics. However, let's now consider energy before and after the switch closure: E = 1/2 * C * V(exp2). In other words, energy increases as the square of the voltage, but only linearly with respect to capacitance. In the example at hand, capacitance doubles, but voltage halves. Since 1/2 squared is 1/4, half of the energy appears to disappear. It really does not disappear, of course, but does anyone have an explanation for the phenomenon? If not, I'll post the answer. Incidently, energy stored in a capacitor or inductor is the dual of the Newtonian relationship about energy in moving bodies, e.g., E = 1/2 *M * V(exp2), where E is energy and M is mass. The fact that charge or momentum are conserved whereas energy APPEARS TO NOT be conserved is with us in everything we undertake. In a few words, entropy alway wins, so to speak. An automotive driving teacher knows that stopping requires four times the distance at twice the speed, so the concepts are not totally lost on those without formal engineering training. The concepts among many is not related to the underlying physical reasoning and laws, however.

There exist few enough engineers who really understand, love, and live by the profession. With patience and diligence, it is possible to answer questions from those without the rigorous training and education, tailored in a manner to develop a greater appreciation, understanding, and recognition of the ever-present role that physics, primarily, plays in our everyday lives.

Just my 3 cents worth (inflation, you know).

BernieK

OK, Ya got me! I agreed with Andy, but I have to admit you are also very right! I assume the 'dissapeared' energy in your capacitors ended up as heat. If not, Ya got me twice! Dick

Hi again from BernieK. This is primarily a response to Dick, concerning the apparent loss of energy from the parallel connected capacitors. I can tell you that heat does not enter into the answer. Strong hint: Think about real world means of connecting capacitors in parallel, in terms of leadwire length, and H field antenna considerations.

BernieK

WHEW..............Now MIKEL, this explains the pertinent facts and issues in the comparision of electric space heaters......... I'm reminded of the fellow who was asked "do you have the time?". Instead of yes, he told me the time, how it was calculated and how the time piece was made................

In response to Bernie's question of where the energy went, the answer is that work was performed in transferring the charge, and with care applied to the signs, algebraic summing of the total work done accounts for the "missing" energy. Since any ohmic resistance is presumed absent ("no heat is involved"), and we have moved charged particles through a distance, "rapidly" at first, then much slower as the charge equalized, thereby producing time varying fields in the process, energy was radiated.

By any stretch of the imagination, could you be THE Bernie Katz I worked with on powder feeder rate meters some years back? (Technical Dynamics?)

This message is an answer to Greg G's posting. Yes, Greg, I'm the same person you worked with on the gravimetric powder feeder. Also, you are absolutely correct about the capacitor energy question answer. The energy radiates away as an H field (becomes a conventional E and H filed once more than about a wavelength away).

During the telecom crash and an unsavory hired manager, I lost a consultling company of 10 people I had built. So, I'm back to a sole practiionership, specializing in RF, analog, and power supply design.

I remember you from those days. Drop me a line at berniek@technicaldevelop.com if you would, and we can exchange at least some information after all these years. Please note the company name change.

Take care.

BernieK

Andy

How does one say "Happy New Year" auf Deutsch?? I may have known it once, but I forgetted.

Bill

Hi,

I get the feeling that some people want to split hairs down to the Quantum level....... I am not such a person, parts of 1% (unless its cyanide!) do not get me even warm, let alone hot!!

RF losses in a heater.......!!!

With regard to a heater of the type(s) described, the losses that are not eventually heat, probably consist of a very small part of 1%....eg. the difference on your electricity bill is too small to be noticed....and that is the important bit Guys!! Do not miss the wood because there are so many trees about!!!

I feel that although we should give credence to such losses for reasons of accuracy, but they must be appreciated as to what actual effect they will have on costs and the environment.....here that is not taking place.

A heater is a heater is a heater - as someone else mentioned earlier. Assuming only resistive loads, nobody can change the laws of physics to achieve what some companies missleadingly claim.....

The Guest in question that I was unhappy with his comments in this area, would appear to have a personal reason for saying what he said - I would guess financial, but I could be wrong.

It is such comments as these that I personally feel really do not have a place on CR4.

The persons concerned who sell heaters (or anything for that matter!) should run Ads to sell their products and pay for them, not try to missuse CR4 for such things.

Sadly in this case, I do not know the name of the company concerned, because if did know it, I would make sure that I never bought anything that they have to offer, ever!! For the same that I never buy music CDs from Sony BMG after that fiasco with rootkits recently.

I always use such info to tailor my shopping lists!!

So let us call an end to any further such comments and hairsplitting for the rest of 2006 and all of 2007 and hereafter!

So (at the request of someone else, here are the New Years greetings in German!) - "Prost Neu Jahr" (at around midnight on 31-12 with a glass of something good!!) and later " Frohes Neues Jahr" (from the morning of 1-1!) to you all..

I have a 1200 watt space heater, and attached a Kill-a-Watt to it. It only uses 1200 watts on initial startup. Once warmed up, steady state it will pull about 400 watts (in "high" mode) or 300 watts (in "low" mode), with the thermostat on the hottest setting (which keeps it running continuously). This explains how I've seen people run more than one of these on a circuit and not trip the breaker! I'd venture to guess that if the heater drew 1200 watts continuously, the plastic parts of the housing would melt. I haven't hooked my Kill-a-Watt up to other space heaters yet, but plan to in the future.

WHY?????

Why not just use the thermostat to let it cycle on and off as necessary?

Are you implying you are getting more than 400 watts of heat out of it on high mode with your "Kill-A-Watt" ?

YOU ARE NOT!!!!!

And, if you are it is only because it is using more than 400 watts and your measurement is in error. Electric resistance heating is extraordinarily simple: Watts consumed=watts of heat output, period!

Greg

Right on Greg, thanks for the feet on the floor approach, we need more like you in CR4.

Why not just use the thermostat to let it cycle on and off as necessary?

I do that, however, I was conducting an experiment, pointing out that even with the thing cranked up all the way, a "1200 watt" heater only draws 1200 watts for the first few seconds that it is started.

Are you implying you are getting more than 400 watts of heat out of it on high mode with your "Kill-A-Watt" ?

No, I was lamenting the fact that I was only getting 400 watts of heat out of it. I never realized that space heaters had some sort of internal regulator (other than a shutoff if they internally overheat or tip over). I assumed that a 1200-watt heater would always draw 1200 watts (when turned on "high"), so long as the external thermostat were in a position that caused it to run.

Watts consumed=watts of heat output, period!

I took two semesters of Physics and am well aware of that fact. I could not find it documented in any literature that a running space heater only draws its rated wattage at startup, and draws much less than that wattage shortly after it is started up. I don't know anything about their internals and always assumed they drew their rated wattage, continuously, until the thermostat kicked them off. That was all. But, go ahead and read something else into what I said, in order to flame me... Sheesh!

My apologies.

If you spend any time here you too will read the things into a post similar to yours, as I did. At least I would hope so.

This place is awash with bad science, or no science at all, yet there are very many well educated people here too, and they are by far the majority, but the scientifically challenged ones stand out the most, especially when they have posted as a guest. Perpetual motion, violations of every "law" of physics that exist and some that don't because no one thought it was necessary.

If you read all the earlier posts in this thread you will see many claims of electric heaters delivering more heat for the same consumed power, and that was what I thought you were implying.

Again, my apologies for reading something into your post that wasn't intended.

Many of the newer heaters have scalable output or 2 stage thermostats to avoid or minimize the on/off effects and improve comfort.

Join us!

Greg

I suspect that to avoid offending Guest, your most recent post didn't address the "Kill-a-Watt". I'm not sure what this device is, but I suspect it may be either a capacitive device intended to counteract the inductance of motor-driven appliances, or just a plain hoax intended to make the purveyor rich at the expense of people subject to slick advertising. In either case I'm virtually certain it does absolutely nothing to change the actual or apparent energy efficiency of a resistive heater.

dkwarner,

I am in complete agreement with you. Some of these devices can save energy in certain limited conditions involving 4 pole AC induction motors (1725 RPM) running lightly loaded and a few other inductive applications but that's about it. They can't do anything for resistive devices. They typically work by chopping out a portion of the sine wave of a lightly loaded motor, but don't seem to be able to do as much or anything with the 2 pole (3450 RPM) motors.

Greg

masu

Thanks for finding that! That's a pretty reasonable price, and not the hoax that I suspected (although the name may be). I once rescued the KWH meter from a very old house being torn down, and used it to check out refrigerators etc. Since it was so old, it had very low capacity, so could indicate the usage of devices in a reasonable time. I donated it to the local High School when I retired from teaching physics & electronics etc.

It doesn't look to be a bad unit and I wouldn't mind one myself. The only hassle is that I live in Australia and we use a 240V 50 Hz system. I suspect trying to use one here would result in a sudden peak in power consumption followed by the device releasing that smoke that seems to be so critical to its operation.

This dose however raise the question of why dose our guests heater have such a dramatic drop in power consumption as it warms up? I can understand a certain drop but 66% seems to be a bit too high for an element heating up.

Perplexing isn't it?

Hi Masu,

Thanks for the link.

It seems the Kill-0-Watt is a pretty nifty device, and not the kind of device that its name implies, or that I had the occasion to test a few years back. I wouldn't mind having one myself.

As to the lower power consumption of the heater once warmed up, I'm not at all sure why. I have encountered oil filled, ceramic, or bare wire heaters with thermostats that would be (factory) set low enough that even turned all the way up, if the heater was in an area that was approximately normal room temperature, between the ambient temperature and the heat from the adjacent heated surfaces (of the heater itself), would not provide full power, after initial warm-up (in the case of a simple on/off bi-metallic thermostat would operate at a low duty cycle). In a cold environment, the power consumed or duty cycle would be much higher. I suspect that the heater was tested in a "warm" environment, and that in a colder ambient temperature the power would be much greater, due to the control methodology only, and having nothing to do with changes in resistance of the heating element or other causes. Also, it wasn't specified whether this was the steady state draw, or an average over some period, although the implication was steady state.

Greg

I did register... Thanks for the apology.

As you discovered, the Kill-A-Watt isn't some sort of energy-saving voodoo, just a measuring device designed for 120 VAC devices. I can't offer any evidence of "0.2% accuracy," but I've plugged a light bulb into it, and it said the bulb was drawing, I think, 1 watt less than its rated wattage (which seems reasonable)... It's close enough for my purposes. It's a gadget, and at $30, it will probably never pay for itself. Also, it's not as versatile as a multimeter or clamp-on ammeter, but is much better suited for its specific purpose.

My Duracraft heater doesn't appear to have a two-stage thermostat--turning it just past the point of startup, versus turning it all the way to "high," has no effect on the current draw (switching the power switch among off, fan, low, and high positions does affect the current draw). It must only have the scalable output you mentioned.

Segfault,

Welcome to CR4!

The accuracy with the light bulb was excellent, considering that the nomimal wattage is only based on the rated voltage on the bulb, and of course, power in a resistance device changing as a square of the actual voltage (excluding the much lesser change in resistance due to temperature). In other words, if the voltage were to drop by 10%, to .9 of its previous value, the power consumed would drop by .9 x .9, to .81 its previous value, and the watt meter would register .81 of the previous watts.

Greg

As Greg G has pointed out

Power = V²/R

Which means that power is proportional to the inverse of resistance so for segfault radiator to have a 75% drop in power the resistance must increase 4 fold. I cant see this being a straight function of the resistance increasing due to heat so I suspect there is some sort of limiting system within the radiator.

Heaters often have a secondary control system that is designed to limit the internal temperature and I suspect this is what is happening. I would like to ask segfault if his heaters output drops suddenly from the 1200 w to 400 suddenly or slowly? This may give me a hint as to what is going on. I would also like to ask what the ambient temperature was when the test was carried out?

Sounds like a diode is being switched in, effectively cutting the voltage in half and therefore the power by one fourth.

Dick

Hi Masu,

Scalable output as used in some heaters is a distinct possibility because the cost of the necessary components have come down so far, but perhaps it was a case of 2 elements, one being 1200 Watts and the other being 400 Watts, and when applied in series when the switch is in the LOW position, would yield 300 Watts. For 120 V, this would be one of 12 ohms, and one of 36 ohms, yielding 48 ohms when in series (or some other similar arrangement of multiple elements such as two 24 ohm and one 12 ohm, or two 24 ohm with one being center tapped etc.)

As mentioned by dkwarner, a diode might be involved too.

Maybe segfault can enlighten us as to what the arrangement is, and the room temp during his test. What is certain is that the drop in wattage is NOT due to the increased resistance of the element(s) being heated.

Greg

I like dkwarner's idea although diodes are notoriously intolerant of high temperatures. This is definitely a sleep on it problem and since just gone 04:00 so it's time for me to get some shut eye.

I'm going to try to answer all the questions that were raised in one post.

From a "cold" state to "full blast," it ramps up to around 1200 watts in about a minute, and then steadily declines for a few minutes after that. It's definitely not an instant switch down from 1200 to 400 watts. Ambient room temperature is from approx. 60-70 degrees F... At 70, the heater will go down to 350-370 watts with everything turned up all the way, but it would only go down to 400 watts if the ambient temperature were 60.

I am out of town for the weekend and can't give you anything more exact than that--next week, I could do some sort of stopwatch test on the time required to get to a steady state.

Segfault,

Thanks for the feedback.

Well, so far it has all the earmarks of a scalable thermostatic control. These things are so inexpensive now!

I have used 120 mm computer fans with (the now fashionable) LEDs, that like most, have 3 phase AC motors, but this has a VFD, rather than the most common DC to 3 phase inverter, and is thermostatically speed controlled by a small sensor on a pigtail, or the included potentiometer can be used to manually adjust fan speed, and they cost $13 (regular pricing). Now of course, the power controlled is negligible compared to a heater, but the control part of the circuitry is similar, plus it has the built VFD, so I just mention this as an indication of how "invisible", pervasive and cheap this general type of technology is now.

Of course it could be some older, simpler technology that I'm not aware of to scale the output.

Most computer fans have been 3 phase AC/PM (permanent magnet) motors with built in inverters for some time now, having replaced the former brushless DC types. They run smoother, quieter, and last longer.

Greg

It definitely sounds like it has a PID (Proportional Integral & Differential) controller embedded somewhere within the system and more than likely uses a triac to regulate the power going to the element. It could use a FET (Field Effect Transistor) instead of the triac but these are usually fairly expensive items and cost more on their own than the triac circuitry in its entirety.

It's somewhat strange that they have installed a simple on/off control on top of the PID loop. I would guess that the heater comes in several models or is used as a base model somewhere that only has the thermostat control. They just havn't bothered to remove the on/off control when installing the PID loop. Mind you it's quiet possible that it's a reverse engineered product that was copied and the people doing the copying didn't understand how it all worked and just copied everything.

I guess taking it apart and posting pics of the innards would put an end to all speculation...

One thing I have seen in practice is that the motor of a fan that sees heavy use will sometimes slow down as it is wearing out. In that respect, I'm glad it has an internal control to help stop overheating if the airflow is diminished.

I didn't know that most computer fans were now AC with built-in inverters, but I guess that explains the small circuit board (usually behind a sticker) on most of them.

Final verdict: I use the "fan only" mode of the heater to generate white noise at night. A few weeks ago, the fan wouldn't come on (it locked up). It appears the fan was near the end of its life and the thermistor inside the heater functioned properly to prevent it from overheating due to low air flow. I threw the heater away--it had security Torx bits, so it'd be hard to have a look inside (but a good excuse to buy a set of security bits)...

I have succeeded both (A) in breaking off the pins of the security Torxes with a pin punch so an ordinary Torx would work, and (B) using a carbide drill to drill a hole in the end of a regular Torx mounted in a lathe. I've never happened to see a security Torx for sale, but then I've never really looked nor asked. (I just looked, and McMaster-Carr sells a set for $13!).

Dick

I don't think a diode reduces the power that much. The voltage doesn't drop in half, but by about a factor of .707. I use this method to provide a low temperature setting on my soldering iron. It reduces the power dissipation by about 50% when I turn off the switch that bypasses the diode.

We are talking about AC going through a diode so it will cut half the wave form out by not conducting when reversed biased. It will also drop the forward bias voltage by 700 mv as well.

Ahh, I had an inaccurate impression since it hadn't occurred to me that I have been soldering normal components with only 10 watts. The iron is rated 40w.

Don't jump to conclusions!

As you see you have to be careful with Average and RMS volts!

Your iron did drop from 40 to 20 watts.

Wow! Thanks!

Didn't mean to dazzle with math.

I felt compelled to do the math. The discussion momentarily confused me. The analysis of power, volts, amps, power conversion, efficiency etc. is fundamental to my business and I had to re-affirm the fundamentals.

I am glad you did. I used to be able to do integrals almost half way decently. Math is an excellent tool.

I stand corrected on the reduction in power consumption due to insertion of a diode (to 1/2, not 1/4 as I thought earlier, ignoring diode fwd drop). I see that the diode would not reduce the voltage, but rather the time during which the voltage is passed on to the load.

On the other hand, if he was only using his soldering pencil at 10W to start with, the diode may or may not have reduced the power to 5W, depending on the system used to control the soldering pencil power/temperature. All the temperature regulated soldering pencils I have used incorporate a temperature-sensitive switch in the barrell. I assume (dangerous but common process!) that the switch has a fixed switching temperature, and that the temperature control varies something like how long the current continues after the switch has indicated temperature achieved.

Nahw, it's just a 3 dollar type. It is designed to consume a straight 40w.

Then how do you use it at 10W? Plugged into a variac or dimmer?

I have only been using it at either 20w for most things or 40w for high-heat needs. All that I have been using is the diode and the switch to bypass it.

The trick with a diode in the powerline, with a normal switch bridging it is very old. We amateurs used it so that the iron would stay fairly hot while fiddling with components, but not so hot that the tip oxidised. When the switch was used it shorted out the diode and the iron was upto soldering temperature in 10-20 seconds......instead of several minutes that it would take from cold.

Mine would just melt thin resin cored solder when the diode was in circuit, but very slowly!

As demonstrated elsewhere in this column, the wattage was aproximately halved.

The 700mvolt lost in the diode that someone mentioned (I thought silicon diodes lost 600mV?) can be ignored both in 110 & 240 Volt AC systems as it is such a tiny part of the actual supply used, it has no consequence except for hair splitting! Now if it was a 5 Volt AC soldering iron (never seen one!) the 700mVolts would have to be accounted for....

It was a neat and simple trick when we did not have the expensive controllers or temperature controlled irons that businesses had...today they are affordable for the amateur too....

The 700mvolt lost in the diode that someone mentioned (I thought silicon diodes lost 600mV?)

The forward bias voltage drop V_F on a silicon diode depends on a lot of factors like the level of doping etc. The 700mv is just a rule of thumb figure that is meant to roughly allow for all the factors that are involved in V_F. If a more accurate figure is needed I always refer to the appropriate data sheet.

Many thanks, I was not aware that the voltage drop was affected by doping and suchlike, I was under the (false) impression that certain types of base (Silicon or Germanium for example) had each a fairly set (different) voltage drop no matter how or who made the diode. I shall remember that in the future! thankyou.

In the context of a soldering iron though, I feel that with a mains operated unit, we can forget this minor loss in the real world.

Or is there an occasion when it should be taken seriously even with the mains? Am I treating this subject far too lightly? and thereby displaying my ignorance in this area?

For the soldering iron example the diode will dissipate approx. .7v x .233A for the half period (1/4 watt) or 0.17 watts rms over the whole period. I vote to ignore it, since my mains voltage is anywhere from 105 to 120 volts. 0.7 volts just doesn't seem to matter except for sizing the diode. 1N4000 series should be ideal. For the extra 1 cent make it a 1N4007.

I have seen suggestions to use series diodes for dropping voltages from 24 to 12 volts etc, but remember, they are not sharp regulators (use a zener instead) and still dissipate the current times the voltage drop.

Now, in large power converters for DC motors we can't ignore it so cavalierly. The power loss is minimal for the system, but the sizing is critical for heat loss and current carrying capacity. 1200A x 1.2 volts = 1.4kW watts. Good size heat sink and cooling fan required. Motor dissipation is 1200A at 600VDC or 720kW. (Yes, fwd drop in this case can be as high as 1.2 volts, you need to look at the curves for your device and how hard you push them. There is a finite fwd resistance and you reach a point where the fwd volts just keeps climbing. We curve trace on maintenance to check both blocking volts and fwd conduction resistance.)

Uh, Hi all I cant figure out from reading this if its better to turn a oil filled radiator (electric) to high or low to have a better electric bill. My bill is like 650.00 this month and why i do not know. I do have three of these heaters in rooms. I have had 2 for a long time and my billed just doubled and i want to conserve as much as possible.

Don

$650 for one month!? You need to spend a good bit of your energy outlay on insulation and/or sealing leaks and/or double- or triple-pane windows and/or a different source of heating rather than electricity!

I do live in California, but at an altitude of 2100ft, where we have had snow 6 times already this winter. I just had my 280 gallon propane tank filled for under $600, and expect that to last me till fall (house and water heating)

Since you didn't register, I have no idea where you live... (I had already written half of this before I noticed 'Guest' - If I had noticed that at first, I wouldn't have responded at all!)

Yes 1 month, it more than doubled. i almost wonder if the electric copy read it wrong. New Jersey and its warmer this year than last. I dont understand so i was just trying to figure out the most cost effective way to run the extra heaters.They are on from about 4pm till 8 am. every day. Is it better to put them on high and let them warm the room up faster? Or low? We just added the third heater and i starting putting them on low trying to conserve but then i got that crazy bill, and am unsure what to do? I think its great that you even let guests post, Thanks very much.

Don

Hello Don

Yes they do let guests post, but as I indicated, usually if the poster doesn't take the time to register, I don't take the time to respond! Please do register...

The heaters are on at night and not in the day? or did you get that backwards?

When you say low, is that a power level setting or a thermostat?

If it is a power level setting, it will just stay on longer 'till the room reaches the thermostat setting - no change in energy consumption. Energy=power(Watts or kW) * time(hrs), so 0.5kW(500W)*4hrs=2kWh of energy, or 1kW*2hrs=2kWh of energy, or 2kW*0.5hr=2kWh of energy, etc.

If it is a thermostat, the lower you set it, the less energy you will use. I have central heating controlled by a programmable thermostat which I have set to 65°F in the daytime and 55°F at night. I have insulated and sealed my house and added double-pane windows, so my heat loss is low. In most weather the heat does not come on at all during the night; only when the thermostat setting changes from 55° to 65° at 6AM does the heat come on.

Although it is true that all electric heaters convert 100% of the electric energy they receive into heat energy, they are still usually the most expensive source of heat. This is because electric generating plants that burn fuel only convert about a third of the fuel energy heat into electric energy, and depending on the distance from the generator to the user, as much as 10% of that may be lost in the distribution system. Today's fuel-burning furnaces convert well over 90% of the fuel energy into useful heat - only 6-10% goes up the stack. The exhaust pipe on my furnace (which I replaced about 5 years ago) is pvc plastic; they couldn't use that if it weren't pretty efficient!

The bottom line is: 1. Insulate and seal to conserve heat. 2. Use clothing in the day and blankets at night to be comfortable at lower room temperatures. 3. Use the most efficient energy source available. 4. Use electric heat only for spot heating where a person stays relatively motionless for long periods. With the kind of electric bill you are talking about, the return on investment for converting to non-electric heat is going to be rapid!

Dick

Hi Dick,

I will check out the site a little more but i had the impression it was for engineers, well the title i do not have but i will TRY to repair almost anything and i succeed more than fail, so i will investigate further as i only found this page via Googling.

Yes the heaters are mostly on when we are home, at night, low is a power level control and i have learned here that doesn't really matter for my problem. I do believe the heat was high (thermostat) on one heater but chose not to change it do to the family member in that room "feeling cold", but i do believe thats rectified. But the good news is we called the electric company and said "we think it was misread" and they sent out my girlfriend to read the meter and at least over the phone they also agreed they "think it was misread", new bill will be coming soon. I will keep you posted.

I do have a newer oil furnace and my electric bills are generally a third of the last bill. I also have new windows and it a thick wall brick house. the oil/electric heaters are only in the rooms that either don't have good heat or rarely used and then it turned on.

I am sorry it took me so long to respond but it been a little crazy, all i can say is, "thanks a lot"

Don

Although I was trained as a physics teacher with a lot of electronics background, and did teach physics for 32 years, I've now been working as an engineer for 13 years, without an engineering degree. No one has ever complained that I'm not an engineer - So welcome!

My name is Tracy Myers of Santa Rosa, CA. Like I just wanted to say that I totally love my CZ Infrared 1500 plastic heater. It's the bomb, yo. Check it, I was like so cold before…even though I like totally live in Cali…I was still like freezing all the time. You try keepin' up with the styles in the mags and still stay warm. It's like so a challenge, ya know? So like, I was cruising the net blog scene and scoped all the awesome reviews this CZ Infrared heater was rockin', and I like said to myself, I need one of those for my pad. So I like ordered one & it came totally quick, yo….and they were so understanding at that Earth-something company….totally cool. They were like totally patient and answered all my questions, yo. So totally the bomb that after I received my heater and needed help understanding how to use it, cuz like who really has time to like read that user-manual thingy, they were so totally down to help me understand every setting and the do's & don'ts of using my heater, yo. The heater like totally hooked up my pad with this even, comfortable heat that allows me to chill in my threads with no worries, for real. I like totally promoted to all my peeps who like sportin' the mad trends and wanna stay toasty and chill in their own pads. So like totally check the mad skills this heater has at keepin' a girl comfy, yo.

This message is in response to Tracy Myers post. While it appears that you were impressed with the customer service of the CZ Infrared company, there isn't any real information provided beyond your empty, slang-ridden opinions of the heater. I have heard good things and thought you could provide me with more than your review has. What has the state of our educational system come to if the best review you can muster comes across as some muddled rap video.

Umm. I dunno - I bought one of those 'infrared'

heaters. Was not so happy.

Good Morning, my name is Garrison Roberts. My wife and I just bought our first home 5 months ago…moving' up and finally realizing the American Dream. So shortly thereafter we found that it could be very costly during the impending winter to pay the higher propane costs that heating a 1800 sq ft home is…we needed a better solution. So we looked around and found some friends using 2 CZ Infrared 1500P heaters to supplement their home heat. It seemed to do an excellent job in the main areas of their home. So I took the leap of faith and invested in 3 units...they do not disappoint whatsoever. We run our thermostat at a constant 55 F and supplement up to 75 degrees F in our living room, one in our kitchen/dining area, and one in our finished basement that is converted into an office/study. The units perform perfectly and we set them to delay start about 45 minutes prior to coming home for an even, comfortable heat. I run our 3 units for about 12 hours per day for the cost of $1.58 per day or less than $50.00 per month in electrical cost per unit. It has saved us hundreds in potential propane costs this heating season already. I am so glad that I took the leap of faith and decided to choose Infrared heat to keep my new home comfy and warm. Thank you, CZ Infrared.

The savings isn't due to using electricity, but to selective heating of only those areas necessary. A well-designed and appropriately operated central heating system should be able to do the same thing. It does require at least one programmable thermostat, appropriate programming thereof, and probably several closed air registers.

The key to assess the effectiveness question is to consider the purpose in the problem. While all electric heaters transfer the same energy to the environment some may fulfill a given purpose more effectively than others. The effectiveness relation will change if a different purpose is considered.

In short, the law of the conservation of energy only tells that no heater technology dominates all the others for all the purposes. Some are better for this, some are better for that. Thus, it makes sense to spend time studying the case as there is always a heater that is the best for each case.

Dear Mikel

Not to avoid your wishful answer but i use oil heaters and they are great except for the wait time it takes for them to heat up. Another energy conserving space heater we use is a Lasko ceramic element heater. It blows heat by fan through a warmed radiator.

It's low on energy consumption as far as our energy meter shows.

I wonder how safe a space heater is amperage wise when it is connected with a few other appliances.