Electric Heaters

You're missing the heat load part of the equation here....The amount of heat needed is going to depend on the ambient temperature, insulation factor of space and other minor factors...

The heat load is the same in all situations, same size room, same insulation, same ambient temperature. I just want to know why the specs are so different for the same wattage and BTU.

It's known as a sales pitch. The only additional warming you will feel is when your blood pressure sky rockets from being ripped off for $ 385.00!

How long takes your test? Most of the heaters have a heating element. The trick is to get the heat to your room. It is either done by radiation or convection when they have a fan blowing over this element. The feeling can be different when the air in the room doesn't participate fully in the process, what can be affected by - too low air stream - loops that recycle the heat without getting to the places you want.

Also the relative humidity in the room plays a role. Dry air has less heat content for the same temperature.

While they all heat the room the same amount (watts-in = watts-out), I personally prefer the ~$30 infrared-reflector radiant electric units. If you are stationary and about 6-10 feet away, you can "feel" the warmth almost instantly. The cheapest ones only heat the air passing through them and it takes a fair amount of time to feel the room air temperature change.

my homemade electric heater 4000 watts works 100% efficeint i.e it boils two gallons in just 10 to 15 mintues

There is no heater made that is 100 percent efficient at anything. Come-on lets all get real here. You might get 90% or I might give you 95% on a good day but no way are we going to see 100% out of anything made by man today.

If we forget the inefficiency of producing electricity for a moment, and its price, do not forget that wasted electrical energy is given off as heat in resistive environments........

Would you be prepared to tell us another scenario? Where does the loss go?

Doesn't some of the electric current in the circuit go back into the wall where it returns to the power plant? In which case it is lost as heat in the generator windings or the power lines, not in your home. Are you telling us that 100% of the current that comes out of the wall changes to heat, and none goes back in? That wouldn't be a circuit, would it?

If your heater has a high capacitive or inductive component, that could be slightly true, but most good heaters are wound/made to keep inductance/capacitance to an absolute minimum.....

Use of a Inductance/capacitance meter on the element could let you know if that is true.....

Andy

I have only seen resistive heaters her in N America. What do inductance/capacitance heaters look like and how do they work?

Inquiring mind want to know.

You took that completely 180° out of phase. Read slowly!!!!

What I was saying is that if the heater (resistive) had a capacitive or inductive component, then it is possible that there is some efficiency loss.

I wrote:-

If your heater has a high capacitive or inductive component, that could be slightly true, but most good heaters are wound/made to keep inductance/capacitance to an absolute minimum.....

Use of a Inductance/capacitance meter on the element could let you know if that is true.....

Read it through carefully again.........get it now?

If not, you may need to not only read again not only what I wrote, but also read the post I was answering.....which was:-

Doesn't some of the electric current in the circuit go back into the wall where it returns to the power plant? In which case it is lost as heat in the generator windings or the power lines, not in your home. Are you telling us that 100% of the current that comes out of the wall changes to heat, and none goes back in? That wouldn't be a circuit, would it?

So what you are saying is that if there is no inductance or capacitance then NO current goes back into the wall, so there is no loss in the power lines or the generator. Get serious. Please put a little thought into your answer next time, and tell me how current can flow into the house and none will flow out.

Someone else with a good and full understanding of the science!! Thanks.

The only misunderstanding appears to be Andy who seems not to understand the simple law that current is the same in a series circuit. That being the case, the same current that flows into the room also flows out. You are the first to show that you know this. He also seems to not understand impedance matching. When a load is matched to the generator, half of the power is consumed in the generator. I was simply trying to show that electric heaters are not 100% efficient when you consider the whole circuit (despite what Wikipedia says).

Do you pay for the current that runs through your wiring in your house or the power used in your house? Don't mix the two up......

Then read the correct post again that you referred to but appear to misunderstand......

Have a great day anyway.......

If I could have given you more GAs, I would have.

Thanks for a well thought out and researched answer for our "friend".....I wonder if he will actually understand it....?

I will wait and see IF or HOW he replies, but I might possibly have to wait for a VERY long time.....I would bet almost that he will never come back!! But fully prepared to be completely wrong on that point alone!!

You are demonstrating a lack of knowledge & understanding of how an AC fed heater with a purely resistive element actually works.

It was not my intention to start teaching you basic electrics 101 either.....

This is neither the time or the place, so please look on the web for tutorials on the subject.

Of course there are losses in the power lines, but we never spoke about them, we ONLY spoke about the heater itself. A heater element with no capacitive or inductive component will turn all the supplied power into heat as wanted and expected....even the resistive losses in internal wiring and switches will become heat. How effective is that?

You want heat you get heat!!!!!

If you want to start talking fully about losses, you need to start at the power station and research how the power is generated there and what losses are normal, then the transmission at high voltages, those losses, then the local substation and its losses and so on and so on......

I (and most here I expect, if not all) fully understand all of those as it is really fairly simple and not difficult for anyone with a reasonable intellect to quickly learn. I am sure you will also have no problem either.

Have an effective day.

Even after 2 tries, you don't seem to understand the question (at least you didn't answer it). Finally you think of the power lines, but dismiss them. I'm not even going to bring up the radiated power that is transmitted out of the room without adding any heat to it. You certainly won't understand that. Even if you do, you will make wise cracks and put people down. You are getting more obnoxious every day. It must be pretty lonely at the top of your ivory tower. I hope you don't fall. Have a great day.

At least I have no need to use childish playground words on CR4......

The true facts seem to rile you up without the need of anything more.....

Why is that?

By the way, you can say what you like here, I am never offended as I don't EVER let such simple things upset me....it just helps me to think up a further good answer!!!

Its just improves my INSPIRATION I feel, so many thanks.

Being here is like watching the Jerry Springer show!!!!

Have a good one.....

at 50 hertz or 60 hertz the inductance of an air wound coil of nichrome would have a close to zero component compared to the resistance.

at 220V and 1500 watts or 6.8 amps E=IR, so R = 32 ohms

I chose a 12 inch coil, one inch diameter of 100 turns = 20 uH

So the inductive reactance is 0.0063 ohms

or 0.03 as a power factor change, in other words negligible

Well put.

Great answer, combining technical truth and humor.

Just this weekend, I read an ad with "the house guy" in it (who's name escapes me). Utter and total BS, with one incredible distortion after another. Even the order form was unbelievably hokey with two places to check: one, if you are ordering "now" (with 50% discount) and one if you are ordering after the ten day period from "now", in which case you pay full price.

I bet there are people who order after ten days and check the early space, nevertheless... and feel that they are "getting over" on the vendor (while shelling out $175 for a $25 heater.

Is that the one with Bob Vila. He is trying to tell you his heater will heat 1000 sf. It is possible as long as you isolate the room from the rest of the house and it is well insulated with no drafts. The commercial requires you to read between the lines. It is not completely false, but it's not completely true either. The infomercial has been carefully worded to make people think the heater will work as they say, without making any cold-hard claims that could get them in legal trouble. This is one of the most offensive scams on TV.

I had an idea on how to use up all that fissile stuff from the nuclear program.

I believe toasters, frying pans and kettles could be made with 2 subcritical masses, held apart by a variable wedge that you adjusted to regulate the heat output.

The tops of the kettles could be made from clear plastic so the homey glow of the Cerenkov radiation would brighten up the place. Heating furnaces could be made as well...

...and they need not be made too well as you won't be around long to use them or wear them out.....

The only real difference is in the advertising, which is a greater amount on expensive heaters, so you pay more to be "caught" with them.....

Simply, you pay for the advertising.....

i've always wondered about the oil filled radiator type electric heaters ? i have one in my garage and i like it better than the radiant ceramic style cube.

but, is one less expensive to operate than the other ? they both say 1500w .

my neighbor heats with elecrtric baseboard heaters, and we were discussing whether he would save mony by using one of the radiator type plugged into an outlet.

it just seems that the radiator type warm better, is this an illussion or is it because it is using more electricity ?

There are safety issues and comfort issues. The oil filled heaters have much larger radiating area, so the surface can be lower temperature for a given wattage. This makes them safer, because you can touch them anywhere and not get burned. It can also make them feel more comfortable, because as radiant heater they are more like a a camera flash with an umbrella diffuser: the shadows are less intense. (There are also convective effects with a radiant heater: eventual the stuff in the room warms up and starts to cause convection, and it own radiation.)

But in an insulated room, doors closed etc, a 1500 watt heater is a 1500 watt heater. There is no waste, because waste goes off as heat.

perception is probably a big part of my experience........on a cold day, i come into the garage and go over to the radiator and just get this very warm feeling by standing in front of it, i don't know if there is any black body radiation emitted..

plus i can put my wet gloves on the top of it and dry them out while warming my backside.....

When an open coil heater is turned on after a long period there is usually a bad odour given off due to burning dust, this will never happen with the oil filled type heater. Another problem with the open type is that combustibles placed too close may catch fire. But the two types will still give the same amount of heat of course.

GA

Enter coziness.

Open fireplaces and Kachelofen: lots of long-wave IR radiation, said to be the coziest form of heat..

The radiator type also emits IR but depends most on convection.

Infrared radiant electric units emit shorter wavelengths. They are made to warm your skin, not the air. Heating fans give that nasty feeling of "hot head, cold feet" (right, Andy?).

Electric stone heaters emit long wave IR. Air can be kept cooler, with a "fresh" sensation.

These are nice and expensive:

http://www.steinheizung.ch/haufigefragen.htm

I can tell you more about the physics... but it's also a matter of marketing and appearence.

Electric heating is normally a complement and is hard to be simply related to area.

I'm thinking that if it's a heater that just heats up like a radiator with nothing used to stir the air like a fan motor, then it will heat less space, it pretty much just heats up where it's sitting and that's it.

The other type has a fan motor and blows the warm air and stirs the air a little, with that you get more coverage because it will bring the cooler air in to the heater to warm up as well.

if you want to heat the place up, go get one of those smudge pots they use in the orchards during freezing season, They burn on kerosine and generate their own air movement. There's also those kerosine heaters that look and work like jet engines and produce 150,000 BTU's, something that gets Tim the Toolman Taylor excited.

If technical ratings are all the same, then I can say the difference will be solely dependent on one's perception and sensitivity! If an individual has a very good circulation and blood perfusion, then it is possible he/she may feel a bit more sensitive to any minor ambient temperature changes. He/she may not need as much outside heat, ie., from the heater, and since its own internal body system is already providing enough heat and probably looking for just a little supplement from an outside source.

Although several people have given bits and pieces of the answer none have put it all together in one answer. Most people refer to the rating plate numbers but for a more accurate reading you need to used a power meter that actually measures power consumed and the accumulated watt hours over a 24 hour period.

We live in the north and have relied on electric as well as wood heat in various homes. The kind of heat is very important for 'comfort'

Resistance elements that have air flow fan forced across them are not as effective as the radiant (short wavelenght) The oil filled radiator ( longer wavelenght IR) is good for long term use and is safer because it prevents burns from close contact or even a possibility of fires. However both types heat the air not the occupant directly.

A wood fire is also radiant heat but in such volume it can become uncomfortable if too near. At present we rent a home with baseboard heaters and a wood burning stove. In this present cold snap I am wishing I had a couple of the electric types having a parabolic reflector. We found them to be the most economical, not to mention creature comfortable. I used a power meter to monitor consumption.

The secret to economical electric heat is to heat the occupants directly with short wave IR and let the spillover heat the air next. Ever notice how the restaurants with a patio space use the IR fire tube heaters to heat the patrons or else the propane fired 'umbrellas' placed over the tables. Both radiate IR Even if the air temp is well below normal room temp no one seems to mind because they feel the heat from the IR sources. OK I admit these last two devices are not electric but the heating transfer is similar.

I am sitting here under a blanket because the wood stove is not delivering hot air to the other end of the house and wishing I had one of those $30 parabolic dish heaters

GA from me.

"The oil filled radiator ( longer wavelenght IR) is good for long term use and is safer because it prevents burns from close contact or even a possibility of fires."

Stone heaters I have mentioned in my previous post have a shorter wavelength, so they are almost as effective as red hot radiant types but still prevent burns.

brgds

Snel

Ronseto

rating any heater by square footage has to be based on several assumptions. First of all climate, then type and thickness of insulation of the dwelling where it will be used. BTU makes a certain amount of sense provided the user has the requisite knowledge to make necessary calculations. I can assure you that a 5120 BTU heater will not be considered as adequate in my present situation with an outdoor temperature of -20 F but it probably will seem quite adequate for your location.

I was down in Pensacola two years ago when they had a tiny skiff of snow some 10 miles inland. We were comfortable on the boat with a 5000 BTU heater. Right now 20,000 BTU is barely making life comfortable.

Last winter outside temps dropped to -35C and sustained for 3 days steady. We survived using two radiant dish types and one oil filled heater.

How does a simple question turn into an argument; sorry I asked. I already knew the answer before I asked. I only wanted confirmation to be 100% certain. Anyway, thanks for the answers and the fencing lesson. At least someone earned 5 points. Well done.