Space heater - wire or ceramic.

[Oscar Mayer]

I want to buy a space heater for a bedroom. Costco has portable electric space heaters. Wire & ceramic.

What's the (practical) difference?

[Ed P]

The ceramic heaters are a bit more efficient. I've heard they are about

25% more efficient in changing Watts to heat.

[invalid unparseable]

There is no logical reason to believe that. Both are resistive heating elements following Ohm's Law. The difference is that ceramic heaters encase the heating wire in some kind of ceramic so you don't see the red glow of the heating wire.

I have used both. The problem with ceramic heaters is that the ceramic heating unit restricts the airflow so much that you have sit quite close to it to feel the hot air coming out of it, while the traditional wire-coil type allow free airflow for the fan. I don't like ceramic heater for this reason.

Looks like Walmart has better price than Costco for space heaters:

[Ed P]

Nope

Ceramic heaters are electric heaters that utilize a positive temperature coefficient (PTC) ceramic heating element and generate heat through the principle of resistive heating. Ceramic materials possess sufficient electrical resistance and thermal conductivity to generate and conduct heat as current flows through them. They have high strength and durability. Hence, they perform well when used as a heating element. The heating element of ceramic heaters are made of pure ceramic material, but most are composite materials that consist of the encapsulation of metal and ceramic materials. The ceramic material in the latter acts as an insulator but conducts heat to the surroundings simultaneously, which minimizes the heat and energy losses associated with uninsulated resistance wire.

[Ed P]

More information here

[Oscar Mayer]

Thanks. I looked at the "advantages" section.

Chapter 4: Advantages of Ceramic Heaters Ceramic heaters are powered by electricity... Ceramic heaters are easy to operate... Ceramic heaters can quickly and effectively warm spaces and objects... Ceramic heaters are safe... Ceramic heaters can conveniently and flexibly warm spaces and objects... Ceramic heaters are compact... Ceramic heaters can be equipped with thermostats...

OK. But everything above applies to wire heaters also, I think.

I also looked at Consumer Reports and they didn't mention anything about ceramic heaters (even though they tested them along with wire heaters).

[invalid unparseable]

Don't be fooled by word salad of scientific jargon. PTC is in all electrical wires. The Ohmic resistance goes higher as the temperature of the wire gets hotter.

There is no scientific reason to believe ceramic heaters can convert electricity to heat better than bare coiled-wire.

[Bob F]

Positive temperature coefficient. WOW! that is amazing!. Except that resistance wires heater have that too. Their resistance gets higher as they get hotter. Which basically, just regulates their power usage.

Where are you proposing that that "lost" 25% of energy is going.

Resistive electric heaters are ALWAYS 100% efficient unless there is some path for the heat to escape to outdoors by not going into the heated area first. Which is very difficult to do.

In my usage, the primary difference between ceramic and wire resistive heaters is the delay of the ceramic heaters heating up that ceramic enough to feel any heat meaningfully where the heater is pointing.

And that uninsulated resistance wire is why they put out that heat so quickly. Ceramic is a much better heat insulator.

The ceramic heaters probably do have a longer life.

[Ed Pawlowski]

Sorry, I did not know that you were more knowledgeable than the ten sources I found that say the ceramic is more efficient.

[Bob F]

Were they ALL ceramic heater ads or sellers?

[invalid unparseable]

One might think ceramic heaters might have a longer life, because the metal heating wire is encased in the ceramic material, but that's not the case for me. I went through two ceramic heaters in my lifetime. I figured the reason ceramic heaters die faster than bare coiled-wire heaters is that the bare metal coiled-wire actually runs cooler than the encased metal wire inside a ceramic heater because the heat from a bare coil-wire is immediately carried off by the airflow from the fan. So I imagine the metal heating wire inside a ceramic heater might be red hot but we don't see it because the metal heating wire is encased in a ceramic material.

[Retirednoguilt]

Ed, can you explain to us where the "heat losses associated with uninsulated resistance wire" go if not into the ambient air. Isn't that the goal of electric space heaters (generating heat in the resistive elements and transferring that heat into the ambient air)? To me if that was the case, the claim that ceramic heating elements are more efficient is counter-intuitive. It would seem that the more thermodynamically efficient system would be the one that facilitates heat loss from the uninsulated segments of the heating element.

[trader_4]

The last sentence is pure BS. Where does this alleged lost heat go? If two resistive heating elements have the same resistance, then they will generate the same amount of heat, it's I2R.

[trader_4]

I haven't seen even one source and regardless, they are wrong, they can't change the laws of physics. Resistance heating produces the same amount of heat. A different type of heater, eg radiant versus convection can use less power because it directs the heat to a person so you will feel warm without heating the whole room, but two resistance heaters with the same resistance are going to generate the same heat, I2R.

[T]

That does make. The heating coil inside the ceramic has to get hotter to accommodate the insulating effect through the ceramic, wearing out the coils faster.

The only real advantage I can think of is the ceramic is more tolerant to the chemical reaction to whatever debris that gets sucked up and burnt to the coils. But I do not think it is much of an advantage.

Me things that ceramic is more of a marketing tool than a technical tool

[invalid unparseable]

There might be another reason manufacturers push for ceramic heaters. I think ceramic heaters might be cheaper to make, because you need a very long, thick, coiled heating wire to make a bare wire space heater. The wire has to be thick enough to withstand vibration when the heater is dropped to the ground. The long, thick, coiled heating wire in a bare wire space heater has to wrap around in a circular pattern a few times near the front to give enough coverage to transfer the heat to the passing air driven by the fan, while a ceramic heater can use a very thin straight heating wire wrapped inside a ceramic casing. Ceramic and porcelain are basically "baked mud", so the manufacturers save a lot of money on the metal wire. The thin straight wire in a ceramic casing will glow red hot so it will oxidize slowly even when encased in ceramic, akin to the tungsten element in an incandescent bulb burning out due to oxidation over time even though the glass bulb has some kind of ceramic material baked in at the base of the glass to act as air seal.

[Ralph Mowery]

That is correct. If the two or even more types like those oil filled heaters pull the same amount of current at the same voltage the heat will be the same. I have seen some ads that show a small device plugged into a wall socket that advertise heating a large area for almost no money. I bet the companies hit the market and go out of business before the devices can be returned.

I guess that it could be the way the fan moves the heat around the room to make the room overall warmer other than the area near the heater being very warm and areas 10 feet away still being cold.

[rbowman]

While the kids fight over Ohm's Law, one selection on the CostCo page is different, the Presto Heat Dish. That's a radiant heater and is great for small, focused areas. The rest have fans and are convection heaters. For a bedroom you want the latter; for warming you as you sit at your desk you want the former.

Another consideration is the ceramics tend to have thermostats. You can set it for 70 degrees or whatever and it will cycle to maintain that temperature. The wire type usually have two or three settings to switch in more or less of the coils and don't do so automatically.

Disclaimer: there amy be exceptions but all the ceramics I've owned had thermostat settings while the wire type had a two or three position rotary switch.

Anecdotal: The ceramics have lasted longer for me. Depending on the use blowing them out occasionally help since they are dust magnets.

[T]

Me thinks that where they are made is a bigger issue. It is hard to avoid crap from communist china no-a-days.

[Clare Snyder]

I'd like to hear the rationalle behinf THAT. The only difference between exposed wire and ceramic is thermal mass - whicj HOLDS heat but does not make heat. Ceramic radiates better than wire while wire (likely) heats air better (by direct conduction) and cools off faster in a draft. Makes the SAME amount of "actual" heat but less "sensible" heat. Oil dilled electric radiators MAY be slightly better in that regard than seramic, again because of thermal mass and radiant efficiency - something about "black body radiation" if I remember any of my physics from 55 tears or so ago.