Electric Heaters Not 100% Efficient?

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I thought that all electric heaters were 100% efficient.
What is this site talking about when they say:
"During the process of converting electrical energy into heat energy a great deal of it is lost. Therefore an electrical heater is left with 45% of the energy for heating purposes."
http://recomparison.com/comparisons/101103/electric-heater-vs-ceramic-heaters-vs-oil-filled-radiant-heaters /
P.S. I'm back to struggling with whether or not I should use a constantly running oil-filled heater (set on low) in my small workshop or should I run a small electric heater with a fan only during those times when I'm in the shop, usually a couple of nights a week and a few more hours on weekends.
I have both, so the initial cost is not a factor.
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Per the law of physics, they are obviously idiots. The electric energy you are paying for, as registered by the meter, is almost all converted to heat by an electric heater. The tiny, negligible losses would be as heat in the wiring going from the meter to the heater. And even that is converted to heat.
You don't need to know what you're talking about to put up stuff on the web.
There are legitimate differences in how that heat then reaches the person in the room, how it's dispersed, etc. For example, a radiant electric heater that directs that heat directly at where someone is sitting is going to be more economical to run than an electric heater that tries to heat the entire room. But if they both run at 1000 watts they both have the same 100% efficeincy in converting the electric that goes into them into heat.

IMO, the electric heater with a fan is the clear winner. Why heat the shop when you're only there a small percentage of the time? Or buy one of the radiant heaters with a dish that you can pick up at Costco or Walmart for $40. The benefit to those, besides being energy efficient, is that you get heat instantly. Downside is that they are very directional. So, if you stay at one spot it could be good. If you move around, soon as you're not in front of it, no heat.
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wrote:

re: "IMO, the electric heater with a fan is the clear winner."
Even though all electric heaters are 100% efficient, one type vs. another could be cheaper to operate, right?
Obviously 100% of 2 kW is going to cost less than 100% of 5 kW over the same time period, but how does one compare the various types of heaters to determine the operating cost?
Disregarding the specific situation regarding my shop, are oil-filled heaters cheaper to operate than fan-based heaters since the oil retains/emits the heat even when the element is off?
If I wanted to determine how much it costs to run an oil-filled heater "24/7" I'd need to know how often it actually cycled, which would be based on the temperature of the space, which of course would vary over time.
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On Mon, 28 Nov 2011 11:10:28 -0800 (PST), DerbyDad03

I know these were just sample numbers, but FTR, they don't make consumer space heaters this big. Breakers are usually 15 amps which would be 1.6KW, but they don't make heaters that will almost trip the breaker. Big ones aree usually 10 amps, 1100 watts.

That's hard to determine, but how much heat is radiated, conducted, or convected to the outside when the shop is always warm, versus when it is only warm a few hours a day is easier to compare. We know the shop is losing heat or he would only have to warm it up once and it woudl stay that way.
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On 11/28/2011 3:11 PM, micky wrote:

I just bought one that is 5.6KW. It is however run on 240vac and on a 30 amp breaker.
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wrote:

Virtually every one I have is 1500 watts on high and 750 0n low (except for the 3000 watt 240 volt 'construction cube" in the garage.)

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You are right...sample numbers.
The only reason I tossed out those numbers is because the 2 kW figure was used here, in a document which appears to be directed towards "facility managers", not homeowners.
http://www.focusonenergy.com/files/document_management_system/business_programs/understandingelectricbill_technicalsheet.pdf
"For example, if you operate a 2 kW electric heater for five hours, it consumes 2 kW x 5 hrs = 10 kWh"

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DerbyDad03 wrote:

For electric heaters, it's easy. Compare the amperage.

If an oil-based heater retains some heat after the heating element is off, then obviously not all the heat got into the room when the heating element was on.

No, all you need to know is the power draw.
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On 11/28/2011 7:02 PM, HeyBub wrote:

No, compare the wattage.
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On Tue, 29 Nov 2011 10:39:29 -0500, Tony Miklos

resistive load)
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On 11/28/2011 1:10 PM, DerbyDad03 wrote:

Depends on the application.
Fan type can transfer heat to the air faster. Heating to a comfortable temperature if you are infrequently in the shop should be a lot cheaper (as trader said above).
In general, a fan type can be aimed at where you are which can localize the heat more (with other areas colder).
Radiant could also localize the heat (as trader said above). Electric radiant ceilings and probably floors (like hydronic ones) can be comfortable at lower air temperatures, which can reduce energy consumption.
The heaters with Amish built cabinets are best of all with a large advantage for the manufacturer.
You can't just compare on wattage. The amount of time the heater is on has to be included. A fan unit that infrequently heats a shop should be higher wattage than a heater that keeps the shop heated.

The major advantage of oil-filled electric heaters is that the heat transfer is over a much larger area than with rod type electric elements. The surface temperature is much lower. In a baseboard unit, oil filled is not likely to cause a fire. And if I remember right receptacles can be in the wall above them, but not above a rod type baseboard.
--
bud--


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They sure are idiots. Here is a quote from there,
"During the process of converting electrical energy into heat energy a great deal of it is lost. Therefore an electrical heater is left with 45% of the energy for heating purposes"
What I want to know is where did the 65% of the enegery go ? Did it get lost as heat ?? If so that would bring it back up to 100% If it got converted to light, heating the elements to red, that light would hit objects in the room converting back to heat.
The oil filled heaters must get the heat from somewhere, That means it takes a while for the oil to heat and the room is not being heated with this heat.
The only thing even near good about the other heaters is the IR types that direct heat directly at you . You will be warm, but the other parts of the room will be cold. If you sit in one spot to watch TV it is good, but if you go to another chair, you need a coat.
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-snip-

And if you have your back to them, with a 10" crescent wrench sticking out of your coverall pocket-- when you grab it with your bare hand it will leave a blister. DAMHIKT.
Jim
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DerbyDad03 wrote:

http://recomparison.com/comparisons/101103/electric-heater-vs-ceramic-heaters-vs-oil-filled-radiant-heaters /
You are flailing at the wrong issue.
WHAT is your OBJECTIVE?
I assume, that like most of us, you want to save money.
I can think of two reasons to heat.
1) prevent damage from cold in your absence. For most of us, that means to prevent freezing of stuff that gets damaged by freezing. Water and pipes is an example, but by no means, the only one. Dew point is another. You might want to avoid condensation. You may keep a pet gerbil in there...There may be other issues. You want to keep the place barely warm and dry enough to achieve those objectives.
2)Stuff that wants to be warm in your presence. YOURSELF Maybe your CNC doesn't like to work well when the grease is cold. You want to add enough (but no more) heat at the proper time to achieve those objectives. Maybe you want preheat before you get there...maybe you turn up the heat when you arrive.
The most efficient method of warming for yourself is to bundle up. If that's not acceptable, you need to turn up the heat to match the bundling you can tolerate. An electric snuggie will heat YOU efficiently.
Same for equipment that needs a certain temperature range to work properly.
Bottom line is that you heat as little stuff as possible to the smallest degree possible for the shortest time possible. You might find that a dehumidifier is cheaper than heat in a particular circumstance. YMMV. That's how you reach the lowest cost.
As for efficiency, either electric heater will produce the same number of BTU of heat for the same electrical input. PERIOD!. Doesn't matter what the informercial tells you, it's physics...or thermodynamics.
The difference is WHERE those BTU's go. An electric snuggie will heat YOU without heating the whole place. A radiant or forced air heater can concentrate those BTU's where you point it, wasting less heat elsewhere.
There are biological effects that cause you to feel warmer or colder depending on what parts of your body get heated how much.
So, for reason one, temperature and location of the heat source matters. You might want a heater close to your lathe to prevent condensation. That'll be cheaper than heating the whole room to that temperature.
Same for reason 2. You might want radiant heat closer to you. If you can't get the tape off the roll when it's cold, you might want to move the tape.
You have both devices. Run the experiment and collect data from the utility meter. It's far easier than sorting thru all the crap you're gonna get here.
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On Mon, 28 Nov 2011 09:29:20 -0800 (PST), DerbyDad03

Where does he think the rest of the heat goes? It's not what he says, but maybe someone told him that 55%** of the energy was lost at the power plant where oil or gas or sometimes coal is burned, and he thinks that happens at the heater. The author doesn't even have a name. how credible can he be?
I don't remember if this is a reasonable percentage or not.

The second is cheaper. If the shop is kept warm all the time, it will be losing heat to the outside all the time.
In most climates, another way to save money and increase comfort wouldl probably be to use a an electric hotplate to boil away a soucepan of water and increase the humidity to 50% or so. I have a humidifier on my furnace, and on occasion that the furnace hasn't worked, I've boiled a big pot of water on the stove, or run an all-hot shower** into a stoppered bathtub. If your workshop is only one room a saucepan or two might be enough. Start with hot water.
**Be sure to get the soap out of the way. Also dangerous if you forget the water is running and the tub overflows. So I switched to the stove.

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In typed:

http://recomparison.com/comparisons/101103/electric-heater-vs-ceramic-heaters-vs-oil-filled-radiant-heaters / They're dsplaying more than just their ignorance; look for better information! IIRC 100 watts is about 340 btu's; making easy samples to work with.
If an electric heater consumes 100Watts, or creates 340 btu in the process of running, the ONLY loss is heat in the wires and possible a transformer if there is one. Efficiency is in the high 90 percentile no matter how you look at it. That heat is given off by the heater's operation - ALL in the area to be heated. HOW can you claim then that the efficiency is around 45%? WHERE is the other 55% of a 100W consumption going to then? Total heat dissipated IN THE HEATER and AVAILABLE FOR HEATING will then be in the order of 300+ btu, NOT 45% of 300! However you've figured this out, you seem to have made a gross error or are including things that you are lying by omission about.

In your case, running anything 24/7 is going to be pretty costly for you no matter what it is. IMO the best heat would be kerosene or #1 fuel oil, a Reddy heater is similar, and a thermostat as made for such appliances. You'll get a fast heat rise, good thermostatic action, and it can be turned off when you're not useing it. I've coupled it up with a ceiling fan to keep the heat curculating down off the ceiling and toward the floor, making everything fairly cozy after an hour or so of running. And, it's switched on/off with the shop lites so that it can't be forgotten and left on. A dual pole switch kills the heater and the lights both.
HTH,
Twayne`

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On Mon, 28 Nov 2011 09:29:20 -0800 (PST), DerbyDad03

How big of a shop and how low of an outside temperature?
The typical electric heater will put out 1500 watts or 5000 BTU. If the outside temperature is below 40, it is not worth even plugging in. In my garage/shop I used a 30,000 BTU unit and it was not enough below 20F so I bought a 60,000 BTU unit.
As for the article you refer to, it is poorly written rubbish. I have no idea what they are talking about oil filled units "conserving more heat". I'd like to see some real numbers on output.
An electrical heater loses 55% of energy to produce heat. Ceramic heaters conserve 85% of the energy. Oil filled radiant heaters have a larger surface area and can provide heat for an extended period of time. An electrical heater comes with high running costs. Ceramic and oil filled radiant heaters have lower running costs as they conserve more heat.
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Ed Pawlowski wrote:

"Conserve heat"? What does that mean? Conserve it so it can be passed on to our children and grandchildren?
Nobody wants to "conserve" heat; they want all available heat dumped into the environment in which the heater is located.
And what is this notion that electric heaters only convert 45% of the available energy into heat when in truth they convert 100% of the electrical energy to heat?
Ceramic and oil-filled heaters do NOT have lower running costs. Both equal coil-type electric heaters in that they convert 100% of the available energy into heat. Virtually ALL heaters that plug into the wall are equivalent in total heat output.
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wrote:

Well said. 1 watt = 3.414 BTU of heat (at least since the 1870s when it was defined). No exceptions so far.
Tomsic
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Actually 1 Watt = 3.414 BTU ___per Hour___
So if you run a 1 Watt heater for one hour it will consume 1 Watt hour of energy and deliver 3.414 BTU of heat.
Or in more useful number
if you run a 1 kW heater for 1 hour it will consume 1 kW Hour of energy and cost about $0.15 and deliver 3414 BTU of heat.
Mark
Mark
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