Off topic sorta -- space heaters

actually one thing I was looking at is the Envi convection heater (440W) but like I say, is there more BTU per watt? I mean if it's a watt it equals a specific BTU, right? obviously out to lunch on the topic.

Electric space heaters are the one thing that is always 100% efficient, because any input power that doesn't get turned into heat because of inefficiency, gets turned into, wait for it ..., more heat :-). Choose the style based on where and how you want the heat: infrared radiant, ceramic block, oil filled radiator, whatever, but they are all 100% efficient. Fan included, because motor inefficiency just makes the motor hot, and the energy put into moving air results in friction to stop the air and reclaims the energy as more heat.

----- Regards, Carl Ijames

-- And I ask you guys because this is my go to group. Even if it's electrical I can get a definitive answer here.

Don't really know Jack S. about heater technology, all I know is a watt is a watt but are ceramic heaters (or any type of electric system) more efficient PER watt?

Is there a type of electric heater than can actually give more BTU per watt than another type? Even if it's a small increase?

I'm talking an indoor heater, not anything that has outside components, heat pump etc. .

THANKS

Right, if you exclude heat pumps then they all give the same BTU/watt.

George H.

I have five Markel radiant room heaters and three 'French' something oil radiator types.

To make the 'room' warm, we use the oil radiator type. Looks like a disembodied steam radiator on wheels. Close to it feels warmer, but the convection air currents do heat the air in the room. Once the furniture is warmed up, quite pleasant.

The 'radiant' heater by Markel is like a portable little fireplace glowing away. With the built-in reflector and pointed at you, you can feel VERY comfortable in the coldest of rooms, just like sitting in front of a fireplace.

The radiant heater effect is perfect *if* you plan on moving around the room, working in the room etc, the air remains somewhat cool and very comfortable to work in. Yet, when you sit down to rest, very 'toasty' and very comfortable. I liked it better than our hot air furnace, which made the room so hot you sweated if you simply walked around, yet when you sat down you froze, so we shut off the hot air furnace and went for a simple Markel radiant heater sitting close by. PS: the dog learned how warm it was so tended to hog all the heat, even lying in front of the heater when it was turned off in hopes...

There you have some decisions to make. What exact form of heat do you want? For heating the whole room those French made oil radiator types are great. For heating a human being and not so much heating the whole room, use the Markel radiant heaters. We would actually switch back and forth depending on how we were using the room.

For what its worth, we used to live in California in a 15 room 100 year old home with gigantic trees around it. The trees were too big to put your arms around and went up 30-40+ feet, shading our home and as natural air conditioners kept us pretty cool. One summer as we were sitting in front of our Markel radiant heater barely stayiing comfortable we listened to the news describe how the latest heat wave was having everybody running their airconditioners causing so much demand that there were expected power failures and brownouts! We thought, "we're freezing sitting in front of a heater and everybody else is running air conditioners?!" If poeple built homes like we lived in there wouldn't be such an energy shortage. Anyway, later that week we actually could turn off our room heater and for the first time were 'comfortable' then the news announced record heat wave today is 106 degrees! and we thought it had just got up to normal. Further note, we had an arson caused fire that took out buildings and four trees with flames going 60-70 feet in the air, made national news the fire was so big. Well, after our trees were gone, we roasted every summer.

ical I can get a definitive answer here.

s a watt but are ceramic heaters (or any type of electric system) more effi cient PER watt?

tt than another type? Even if it's a small increase?

eat pump etc. .

I had been looking at these Envi convection heaters for a small bedroom 12x

12 but yeah, like I thought, a watt is a watt. The oil heater thing sounds interesting -- I was just now looking at those on Amazon, a Delonghi with a timer and thermostat. Trouble is I want to try and find something with 3 s ettings and a low of 400 - 500 watts because I bet that's all I'm going to need, I like to sleep cool. Most of the low settings I see are 700 - 750.

ical I can get a definitive answer here.

s a watt but are ceramic heaters (or any type of electric system) more effi cient PER watt?

tt than another type? Even if it's a small increase?

eat pump etc. .

By definition, an electric heater converts electric power to heat with a re sistance element. The best you can do is one watt per watt, the conversion efficiency gets less if you have some kind of overhead like a blower. BTU i s a unit of energy, BTU/Hour is the pertinent unit of power (because heat l oss through building materials is rated in that unit), with 1 Watt= 3.41 BTU/Hr. If you go to something like a heat pump, the electric input power i s not used to heat, it is used to circulate energy around, usually from an outdoor heat source to the indoor air or possibly fluid in the case of radi ant heat. With that technology it is very easy to produce up to 30 BTU/Hr h eat output per Watt of electrical input without going to extremes, and that accounts for all the overhead loads like blowers and pumps. I won't go int o fuels because fuels are bad, burning things is bad.

ical I can get a definitive answer here.

s a watt but are ceramic heaters (or any type of electric system) more effi cient PER watt?

tt than another type? Even if it's a small increase?

eat pump etc. .

A watt is 3.4 BTU's per hour. So one can say there is no difference for any type of electric heater ( excluding heat pumps ).

However there can be big differences in how efficient a heater is in keepi ng you warm.

If a heater warms the air and the air then goes up to the ceiling , that is not too good at keeping you warm. A heated floor may be better at keeping you warm. Or a ceiling fan might help to keep the air evenly warm.

For sleeping a electric mattress pad might be best. They don't do much at heating the room, but do heat the bed. They use about 150 watts when they are heating. You could get pretty much the same result by putting some lig ht bulbs below the mattress and use a light dimmer to control the amount of heat. Being of course careful to make sure nothing overheats and burns do wn the house.

Dan

is a watt but are ceramic heaters (or any type of electric system) more ef ficient PER watt?

watt than another type? Even if it's a small increase?

heat pump etc. .

2x12 but yeah, like I thought, a watt is a watt. The oil heater thing sound s interesting -- I was just now looking at those on Amazon, a Delonghi with a timer and thermostat. Trouble is I want to try and find something with 3 settings and a low of 400 - 500 watts because I bet that's all I'm going t o need, I like to sleep cool. Most of the low settings I see are 700 - 750.

A watt is indeed a watt.

To get 400w from a 700w heater, put a diode in series. Don't do that with f anned heaters of course :)

The only heaters I can think of offhand that give >1 watt out per electrica l watt in are heat pumps, tracking sun reflectors and electrically assisted combustion units. And for the really ambitious, nuclear reactors.

NT

If you can get a reverse cycle air conditioner. It is a much more efficient than a simple 'heater'

The laws of thermodynamics as I interpret them say that the only possible answer is "no".

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umop apisdn

In looking at new oil models, its hard to find all the specs. I've bought several oil heaters of the standard size over the years. Most were close to

500 watts on low. I see some smaller ones, but they are700 watts only. I wanted a smaller one to fit in a trailer. The advantage of the larger unit, it stays under 200 degrees on low. Well over 200 degrees on high. The thermostats generally work well, but use on high will shorten overall life of contacts if mechanical. Non of mine leaked, but I have heard of them leaking. I don't trust radiants and fans, but I use them with caution.

Greg

I had a water filled one, both thermal cutouts failed, but the overpressure valve worked and it pissed hot Chinese tap watter all over the carpet, I unpluged it before it got more interesting.

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umop apisdn

That was it! yes the DeLonghi. Except their !#$#@!@#$ thermostat and timer switches make a LOT of loud clicks. Always woke me up so could never use that 'feature'. Just a 'heads up' in case you plan on having it near by while you 'try' to sleep. You're better off to put on a 'variable' controller and let that oil filled radiator run 100% of the time. Simply adjust the variable to get the temp where you want it

The total heat energy will be the same whatever heater you use, but it can be in different forms: radiant infra-red (long or short wavelength), convected (natural or forced) or conducted. In addition, you have the warm-up time to consider.

A room full of warm air can still feel cold if the surfaces are all cold, because there is no long wavelength IR impinging on your skin. A radiant heater can warm one side of your body, but the other side will be cold until the surfaces on the opposite side of the room warm up and begin to emit IR (wear a camp-fire blanket?).

A heater using natural convection will warm the top half of a room but leave the bottom half, and your feet, cold. A fan-assisted heater at a low setting may make you feel colder because it stirs up the air, but at a higher setting it will feel warmer and it can be arranged to blow warm air on your feet (and up your trouser legs or skirt).

Underfloor heating or heating embedded in the walls will take a long time to warm up, but can give pleasant background heat; but good insulation is needed to reduce heat losses through the surface. On interior walls the losses won't matter as much.

There is no single type of heater that gives all the advantages and none of the disadvantages, so you will have to decide which is most important for your circumstances. In particular, if you need a short warm-up time, this could rule out everything except radiant or fan-assisted convection.

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~ Adrian Tuddenham ~ 
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