Do fan heaters of similar ratings perform differently?
I have a couple of small-box fan heaters.
Both are rated at 2Kw, but one heats a room faster than the other.
The better one is slightly bigger, and has a slower-running fan.
The other one is very compact - one of the reasons I bought it - and has a ceramic panel in front of the fan, so is technologically more advanced.
But I think its fan is too small and spins too fast to work well.
Any thoughts?
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There is unlikely to be any material differnce in the efficiencuy of converting electrical energy into heat.
One just seems to be distributing it better than the other - a difference in effectiveness rather than efficiency.
Assuming of course that they are actually both consuming the rated, or at least the same, power. If you have an OWL meter or similar, check the consumption - you might just find that the more effective one is actually just using more electricity.
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>>There is unlikely to be any material differnce in the efficiencuy of converting electrical energy into heat.
Disagree. There cannot possibly be any difference whatsoever in the efficiency of converting electrical energy into heat, unless you have an atomic reaction. Which I hope you haven't :)
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>> >>There is unlikely to be any material differnce in the efficiencuy of converting electrical energy
>> into heat.
>>
>> Disagree. There cannot possibly be any difference whatsoever in the efficiency of converting electrical energy
>> into heat, unless you have an atomic reaction. Which I hope you haven't :)
I like the way you want to disagree even when you are ageeing. Of course there's essentially no difference. I just didn't want to get into a debate about the proportion of energy consumed by the motor etc etc.
So ner. I'm right.
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;)
You're still at it. Why caveat it with "essentially no difference"?
Last edited by: Mapmaker on Fri 28 Oct 11 at 12:18
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>> >>There is unlikely to be any material differnce in the efficiencuy of converting electrical energy
>> into heat.
>>
>> Disagree. There cannot possibly be any difference whatsoever in the efficiency of converting electrical energy
>> into heat, unless you have an atomic reaction. Which I hope you haven't :)
Agree and disagree. While there can not be any difference in the TOTAL amount of heat generated given a specific power inout, WHERE that heat is in the circuit and HOW EFFICIENT it is at distributing that heat into a room varies ENORMOUSLY.
I could build a device that consumes 2KW of power ( and hence generate the same amount of heat as a fan heater) and it could barely raise the level of the air around it by 2c at a distance of 2 feet.
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You are complicating this by bringing a fan heater into it. It cannot be disputed that "there cannot possibly be any difference whatsoever in the efficiency of converting electrical energy into heat, unless you have an atomic reaction," which was the assertion of the poster above (sorry I cannot remember who).
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>> The better one is slightly bigger, and has a slower-running fan.
That's probably the answer. Although both are rated at 2KW, the one with the faster fan is pulling in more cold air than the one running slowly and is cooling the heating elements more and therefore you're getting less heat output. I suspect once the cold air has been warmed up a bit by the heater, it'll run more efficently.
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Ive got two that I use to dry out car interiors, both rated the same, but one kicks out much more heat than the other.
The hotter one runs slower, that seems to be key.
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The slower one might be outputting hotter air (air is in contact with heating elements for more time), but less of it ie. total heat output is the same.
Same as (say) a 10kW electric shower - controlling the flow changes the temperature of the water, but the total heat output is always the same (10kW).
Last edited by: Focus on Fri 28 Oct 11 at 10:46
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Perhaps, but one is far more effective in real use.
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>>cooling the heating elements more and therefore you're getting less heat output<<
No! 2kW is 2kW !
Efficiency in converting the electricity to heat is 100% (or as near as damn it). If you put 20 100W bulbs inside a fridge and close the door the heat output to the room is still 2kW (plus what ever the fridge consumes).
Your perception of the heating effect may be different however.
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Yes... the same perception that makes some folks think a modern car goes better for a service.
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>> Yes... the same perception that makes some folks think a modern car goes better for
>> a service.
>>
Agreed there are no points to wear and mess up the timing now, but I'd argue that a modern car may well go better for a service -
I've seen a VW Polo recovered to an Indi garage, despite its fully stamped service book, all it needed was the air filter and spark plugs to resurrect it.
Somewhere between "not going" and fully working there must be a mid ground with partially blocked filter.
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>>>I've seen a VW Polo recovered to an Indi garage, despite its fully stamped service book, all it needed was the air filter and spark plugs to resurrect it. Somewhere between "not going" and fully working there must be a mid ground with partially blocked filter.
Fair point but in truth with diesels and many newer petrols that have long life air/fuel filters and spark plugs about the only change is that fact they may well have washed the car and dusted the dash.
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>> >>cooling the heating elements more and therefore you're getting less heat output<<
>>
>> No! 2kW is 2kW !
>>
But you don't know for sure that the consumption is the same unless you check it. I have a 700w rated oil filled rad that seems only to consume about 400w in the on cycle.
Something else you might check is that if either is thermostatically controlled it might be switching the element off periodically.
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>> >>cooling the heating elements more and therefore you're getting less heat output<<
>>
>> No! 2kW is 2kW !
>>
>>
>> Efficiency in converting the electricity to heat is 100% (or as near as damn it).
>> If you put 20 100W bulbs inside a fridge and close the door the heat
>> output to the room is still 2kW
Nope temperature in the fridge is 2KW.
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>> Your perception of the heating effect may be different however.
No - the efficiency of distributing heat to the room will be different. No perception about it.
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>>Nope temperature in the fridge is 2KW. <<<
Come on you know better than that!
when was the last time you measured temperature in Watts? :)
I stand by what I have written,100%!
The energy input into the room is exactly same. The way it warms the air (and your measure of comfort), in the room is what you perceive.
Last edited by: pmh on Fri 28 Oct 11 at 13:51
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>> The energy input into the room is exactly same. The way it warms the air
>> (and your measure of comfort), in the room is what you perceive.
Absolute and complete rubbish. With your 2kw input power into the interior fridge, you will NOT be getting the same heat out into the room.
heard of insulation?
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>>Absolute and complete rubbish. With your 2kw input power into the interior fridge, you will NOT be getting the same heat out into the room.
heard of insulation? <<<
So where does the energy go then? :)
I am still interested in your concept of watts as a measure of temperature. Come on - please explain.
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The energy is going into the fridge full of light bulbs.
The question you should have asked is "where is the heat going"
And the answer is a proportion is staying inside the fridge, a proportion is rediating inot and being dissipated by the floor, and not much is heating up the air. The bit where you are a person feels the heat.
>I am still interested in your concept of watts as a measure of temperature. Come on - please explain.
Electrical and thermal watts
In the electric power industry, megawatt electrical (abbreviation: MWe[13] or MWe[14]) is a term that refers to electric power, while megawatt thermal or thermal megawatt[15] (abbreviations: MWt, MWth, MWt, or MWth) refers to thermal power produced.
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>>thermal megawatt[15] (abbreviations: MWt, MWth, MWt, or MWth) refers to thermal power produced. <<<
you have said it yourself - 'thermal power produced' - that is not a measure of temperature!
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Just splitting hairs to deflect the argument away from the fact your heat in the fridge is going nowhere.
I will believe you, IF you can tell me the temperature rise inside the fridge, and the temperature rise 12 inches away from the side of the fridge in degrees Celsius, for a 2kw power input.
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And I wonder if you have heard of the concept of a thing called "an oven" Designed to contain heat within itself.
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>> And I wonder if you have heard of the concept of a thing called "an
>> oven" Designed to contain heat within itself.
Rubbish.
That is completely different. An oven has a thermostat, therefore once it reaches the desired temperature the heat source will turn off. Insulation will therefore delay the period before the heat source is required again.
In the case of the lightbulbs in the freezer, they will continue to put out heat until either the world ends, they blow, or the electricity board turn off the supply. Therefore the freezer will reach a steady state position whereby the freezer is emitting heat at the rate of 2KW, just like a radiator - or indeed just like 20 100W bulbs (if you could still buy them).
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>> And I wonder if you have heard of the concept of a thing called "an
>> oven" Designed to contain heat within itself.
>>
You have never worked in a kitchen? :) It gets pretty warm however well insulated the oven is.
All about steady state conditions, the interior of the fridge just keeps heating up until the loss of energy on the external surfaces is equal to the input energy. Not an effective way of heating the room quickly, but once it has settled to steady state, the heat output is exactly the same as a 2kW fan heater.
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> You have never worked in a kitchen? :) It gets pretty warm however well insulated the oven is.
Yeah they open the over doors from time to time,
So now I have got you to admit that steady state, which could be several days, will heat the room as well as a fan heater,
By which you admit its not as efficient at the job as the fridge full of bulbs,
And it wont actually disipate all its heat out into the room, there will be a hotspot in the floor under the fridge.
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>>heard of insulation?
Steady state, Zero.
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I'm getting confused.
Would the little heater work better if I put it in the fridge?
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Madf says yes, I say no.
The silly pfd should open the door.
Last edited by: VxFan on Fri 4 Nov 11 at 10:43
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Only if you put a couple of light bulbs in with it
*confused*
Pat
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What happens if you turn the bulbs on?
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the fridge catches fire..
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>> Would the little heater work better if I put it in the fridge?
They'd be no room for the heater because of the elephants. I know they're in there because I've seen the footprints in the butter.
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If we carry on like this Stephen will pull the plug in despair:)
Pat
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Iffy is a very naughty man.
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Another question. The farmer next door has just built a new garage, and was busy insulating it. I asked him if he was going to heat it and he said no. So what is the point of insulating then, I said. So it doesn't get as cold inside, he replied.
But surely for an insulated garage to work, it must need a heat source. Otherwise it will just be the same as outside temperature. ie. cold? Although granted, it will not get as cold as quickly as the outside temperature drops, but by the same token will stay colder for longer when the outside temperature goes up.
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Not steady state. Temperature drops at night, quite a lot. A well insulated garage will retain quite a bit of heat compared with an uninsulated one.
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Efficiency of fan heaters - Manatee
