"Eeyore" wrote in message
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Arfa Daily wrote:

"Richard Crowley" wrote in message
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"Eeyore" wrote in message
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Serge Auckland wrote:

"Eeyore" wrote
Serge Auckland wrote:

Quite apart from the problems of disposing of old CFLs, I question
the
whole principle of Low Energy lighting. If you have a conventional
bulb,
much
of the energy output is in the form of heat, which will help heat
the
room,

and consequently will reduce the need for other heating, central
or
otherwise.

That's sort of fine if you want extra heat. Often as not you don't.

If the central heating is on, then you are, by definition, needing
extra
heat. The heat output from lighting will mean that the room
thermostat
(or
radiator valves) will turn off that bit sooner.

Not really.

The heat from most lamps hangs around at ceiling level. It does sod
all
to warm
a room.

I suggest you compare sitting in front of a 1kw bar electric fire to
switching
on ten 100w light bulbs to see how true that is.

Look at all the energy that is wasted producing light! :-)


What happens to all the 'waste' heat produced in vacuum "filled" bulbs
that
used to be, if not still are, produced for garden use ?

What vacuum ?


It can't be radiated
into the atmosphere, as the envelope is substantially cold to the touch.
Does the fact that it must be hanging around in the vicinity of the
filament, modify the power consumption of the lamp compared to its light
output ? Does this make it a low(er) energy lamp? Why does the heat from
the
anode of a power tube readily radiate across the vacuum, but the heat
from
the filament of a vacuum light bulb seems not to? d;~}

Both do. It's called infra red radiation.

There's also conduction too.

Graham


Agreed that *should* be the case, but the fact is that the envelope of a
vacuum light bulb remains substantially cold in use, whilst a 6L6's envelope
will take the skin off your fingertips after a few minutes use ...

Arfa