wrote:

On Saturday, 4 July 2020 13:32:04 UTC+1, Roger Hayter wrote:
Max Demian wrote:
On 04/07/2020 11:55, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Friday, 3 July 2020 11:19:23 UTC+1, Dave Plowman (News) wrote:

So you stand by his claim that an electric convector heater is 100%
efficient? Just curious.

I said some are, not all are. Oil filled ones that overheat, glow red
hot & catch fire may have more heat output than input


And those that simply expand? As all will?

It only expands once. After that it is 100% efficient.

And, of course, the heat stored during expansion will be released when
it cools down.

Obvious to everyone but Dave. Pressing a spring by expansion then
releasing it by unexpanding doesn't really do any work, it just
temporarily stores some energy.

He'll never get it though. He still thinks a resistor turning electricity
to heat is imposible.


NT

Of course in the spring case some of the energy is lost as heat, but in
the heater case none need be lost as mechanical work.



--

Roger Hayter