Physics / heating question
Discussion
If I run a portable fan heater in a room it warms the room up.
If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
Apart from wasting some heat warming the metal sheet, I'd guess to start with you'd get a hot-spot in front of the heater and the rest of the room would be cooler.
Eventually (many hours later) it would be exactly the same, assuming the heater hasn't got too hot and burned out.
Metal has a low specific heat so wouldn't help much. Use bricks and you've invented the night storage heater.
Eventually (many hours later) it would be exactly the same, assuming the heater hasn't got too hot and burned out.
Metal has a low specific heat so wouldn't help much. Use bricks and you've invented the night storage heater.
No real benefit. The sheet of metal is basically like a very small storage heater. It will get warm (reducing the heat in the air by the same amount), and when you turn the heater off, the metal will give off its heat.
The net effect is (1) no change to your electric bill (2) room takes longer to warm (3) rooom stays warm longer as metal gives off its heat. All in all negligible effect with the size of metal you are talking about.
A bigger effect happens with cast iron log burners, the fire energy heats the iron, that after the fire goes out continues to put some stored energy into the room.
The net effect is (1) no change to your electric bill (2) room takes longer to warm (3) rooom stays warm longer as metal gives off its heat. All in all negligible effect with the size of metal you are talking about.
A bigger effect happens with cast iron log burners, the fire energy heats the iron, that after the fire goes out continues to put some stored energy into the room.
evenflow said:
If I run a portable fan heater in a room it warms the room up.
If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
Sell squares of metal in shiny boxes with the line 'Enhance your heating by 20%!' You'll make a fortune this Christmas If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
NB: Add a bit of mumbo-jumbo about the molecular structure of iron.
Simpo Two said:
evenflow said:
If I run a portable fan heater in a room it warms the room up.
If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
Sell squares of metal in shiny boxes with the line 'Enhance your heating by 20%!' You'll make a fortune this Christmas If I run it for the same amount of time, but place it directly in front of a 1ft x 1ft sheet of metal, is there any benefit? The heater would heat the metal up and there would be residual heat in the metal when the heater switched off.
I know there's no more energy but would it make any tangible difference?
NB: Add a bit of mumbo-jumbo about the molecular structure of iron.
In actual fact all a fan heater does is warm the air, the room would only feel truly warm after all the furniture and everything else was at a comfortable temperature.
Hence why underfloor heating with pipes embedded in thermal mass is superior to ALL other forms of heating. It's the radiant effect that matters - not air temperature.
caziques said:
Hence why underfloor heating with pipes embedded in thermal mass is superior to ALL other forms of heating. It's the radiant effect that matters - not air temperature.
Not too nimble on controllability though - you have to heat up 10 tons of concrete before anything happens. And carpet is a good insulator. I like carpets. UFH is also pretty impossible to retrofit, practically or financially.Hoofy said:
Add "The truth that mainstream media are hiding from you." and "Big pharma don't want you to know this heating hack." to triple the sales.
Can you start on Monday? Edited by Simpo Two on Thursday 8th December 09:41
Nimby said:
Apart from wasting some heat warming the metal sheet, I'd guess to start with you'd get a hot-spot in front of the heater and the rest of the room would be cooler.
Eventually (many hours later) it would be exactly the same, assuming the heater hasn't got too hot and burned out.
Metal has a low specific heat so wouldn't help much. Use bricks and you've invented the night storage heater.
This.Eventually (many hours later) it would be exactly the same, assuming the heater hasn't got too hot and burned out.
Metal has a low specific heat so wouldn't help much. Use bricks and you've invented the night storage heater.
All you've done is store a bit of the heat. No different to running the heater lower and longer.
Put some liquid Sodium (pre boiled on your oven) in a sealed jar in front of the fan heater. That will keep the heat in for ages after you turn the fan heater off.
Send us a video as to how well it works by the way.
I've a friend in the USA in Denver whom has his underfloor heating filled with heat transfer oil and a secondary Heat Exchanger with water off the system boiler to heat the oil. That stays lovely and toasty and his calcs always show less energy use than his architect reckoned would be the cost for a straight direct water system.
Send us a video as to how well it works by the way.
I've a friend in the USA in Denver whom has his underfloor heating filled with heat transfer oil and a secondary Heat Exchanger with water off the system boiler to heat the oil. That stays lovely and toasty and his calcs always show less energy use than his architect reckoned would be the cost for a straight direct water system.
Allegro_Snapon said:
I've a friend in the USA in Denver whom has his underfloor heating filled with heat transfer oil and a secondary Heat Exchanger with water off the system boiler to heat the oil. That stays lovely and toasty and his calcs always show less energy use than his architect reckoned would be the cost for a straight direct water system.
That makes no sense. Now he has two heat exchangers instead of one, so there will be heat wasted from the water/oil one whch could have gone into the heating pipes under the floor. He also has nothing to compare it to, only what his architect 'reckoned' the energy use of a water-based one might be.NB there might be a use for that lost heat - eg the water/oil heat exchanger might be placed in an airing cupboard, but I cannot see how it will use less energy overall.
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