Once again the hot weather has reminded me of just how much I dislike it!
Last night I noticed the amount of heat given of by my ordinary bedside
lamp - IIRC something like 80% of the energy in light bulbs is heat not
light. It made me wonder whether different bulbs would produce less heat?

Argos do a pack of 3 15 Watt BC Energy Saving Fluorescent Bulbs for £6.99

http://www.argos.co.uk/webapp/wcs/st...y?storeId=1000
1&langId=-1&catalogId=2501&productId=104088

These seem to have an ordinary 'bayonet' type fixing. Would these emit less
heat as well as being more efficient?

Can anyone shed some light on the subject?

Richard Blackwood wrote:

Once again the hot weather has reminded me of just how much I dislike it!
Last night I noticed the amount of heat given of by my ordinary bedside
lamp - IIRC something like 80% of the energy in light bulbs is heat not
light. It made me wonder whether different bulbs would produce less heat?


A lot more than 80% - more like 95%.


Argos do a pack of 3 15 Watt BC Energy Saving Fluorescent Bulbs for £6.99
These seem to have an ordinary 'bayonet' type fixing. Would these emit less
heat as well as being more efficient?

Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature. Many
(most?) of the cheaper ones have a truly horrible spectrum, and
everything end up looking yellow. You need to find some that you are
happy with. Personally I like Phillips ones, and have used them a lot.


--
Grunff

Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature.

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

--
Please add "[newsgroup]" in the subject of any personal replies via email
--- My new email address has "ngspamtrap" & @btinternet.com in it ;-) ---

In article ,
Colin Wilson writes:
Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature.

The colour temperature of pretty well all those you can buy is 2700K,
same as a filament lamp (and intentionally so).

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

Which can be really handy in a bedside light.

--
Andrew Gabriel

Richard Blackwood wrote:
Once again the hot weather has reminded me of just how much I dislike it!
Last night I noticed the amount of heat given of by my ordinary bedside
lamp - IIRC something like 80% of the energy in light bulbs is heat not
light. It made me wonder whether different bulbs would produce less heat?

Ulitmately it's *all* heat, it's just that the light gets turned into
heat further from the lamp. The only energy you lose is the amount
that goes out of the window as light - not much.

--
Chris Green

"Colin Wilson" wrote in message
t...
Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature.

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

Sometimes; you have to switch ON a CF 'bulb' in the morning if
you want to read by it in the evening! OK! That's a slight hyperbole;
but they are slow to come to full brilliance. They are fine for
lamps which will be ON for hours ... but not for places where
the lights will be switched ON for short periods (toilets, bathrooms,
bedside lamps, for instance)

--

Brian

Brian Sharrock wrote:

Sometimes; you have to switch ON a CF 'bulb' in the morning if
you want to read by it in the evening! OK! That's a slight hyperbole;
but they are slow to come to full brilliance. They are fine for
lamps which will be ON for hours ... but not for places where
the lights will be switched ON for short periods (toilets, bathrooms,
bedside lamps, for instance)


Again, I've found this to vary greatly between makes. Some are very
poor, taking 10mins or more to reach max output, while others do so in a
few seconds.

--
Grunff

"Richard Blackwood" wrote in message
...
Once again the hot weather has reminded me of just how much I dislike it!
Last night I noticed the amount of heat given of by my ordinary bedside
lamp - IIRC something like 80% of the energy in light bulbs is heat not
light. It made me wonder whether different bulbs would produce less heat?

Argos do a pack of 3 15 Watt BC Energy Saving Fluorescent Bulbs for £6.99

http://www.argos.co.uk/webapp/wcs/st...y?storeId=1000
1&langId=-1&catalogId=2501&productId=104088

These seem to have an ordinary 'bayonet' type fixing. Would these emit
less
heat as well as being more efficient?

Being "more efficient" and "emitting less heat" are two sides of the same
coin. It is precisely because incandescent bulbs convert so much of the
electrical energy into heat, that they are inefficient as light sources. So,
the answer to that last question is most definitely "yes".

Older types of energy saving bulb had rather primitive ballasts in the base,
so used to get quite warm themselves and weren't as efficient as the makers
would have you believe, but the newer ones with electronic ballasts run much
cooler.

Rick

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

Which is absolutely brilliant for a bedside light. I would NEVER fit an
incandescent light for this, for several reasons.

1. Energy efficiency (obviously)
2. Safety. (bulb temperature when half asleep)
3. Eye comfort when turning on at night.

I'm having to get up several times a night to change nappies etc. at the
moment. The fact that you don't have a tear inducing, retina rupturing 100W
of light down your eyeball as soon as you turn on the light is excellent. My
bulbs have exactly the right warm up time to get your eyes going in a gentle
fashion.

I have burnt myself several times on incandescent bulbs before low wattage
ones became available. I suffer from sleep walking.

Christian.

but the newer ones with electronic ballasts run much cooler.

I should mention that it is quite possible to touch many types of low energy
lamp whilst still on. They are usually quite hot, but within the tolerance
of most people.

Christian.

In article ,
Christian McArdle wrote:
I'm having to get up several times a night to change nappies etc. at the
moment. The fact that you don't have a tear inducing, retina rupturing
100W of light down your eyeball as soon as you turn on the light is
excellent.

Heh heh. Think the first room I equipped with a dimmer was a bedroom.

In my bedroom, they're all accessible from the bed - including reading
lamp ones either side - with an overall master two way switched from the
bed and door.

--
*When cheese gets its picture taken, what does it say? *

Dave Plowman London SW
To e-mail, change noise into sound.

"Richard Blackwood" wrote in message ...
Once again the hot weather has reminded me of just how much I dislike it!
Last night I noticed the amount of heat given of by my ordinary bedside
lamp - IIRC something like 80% of the energy in light bulbs is heat not
light. It made me wonder whether different bulbs would produce less heat?

Argos do a pack of 3 15 Watt BC Energy Saving Fluorescent Bulbs for £6.99

http://www.argos.co.uk/webapp/wcs/st...y?storeId=1000
1&langId=-1&catalogId=2501&productId=104088

These seem to have an ordinary 'bayonet' type fixing. Would these emit less
heat as well as being more efficient?

Can anyone shed some light on the subject?


All a bulbs power input becomes heat: about 98% of it becomes heat
directly, the rest becomes light, which turns to heat less than a
microsecond later as its absorbed. The power input always equals the
heat output.

CFLs are the solution, but dont be caught out by the one issue: the
stated equivalent powers are unrealistic, as they are comparisons with
a different type of bulb than everyone expects. The real efficiency
improvement is about 3.5x - 4x, so to replace a 60w bulb you need a
15-17 watts.

If you trust the box's equivalency claims, its dimmer and doesnt look
right.


NT

CFLs are the solution, but dont be caught out by the one issue: the
stated equivalent powers are unrealistic, as they are comparisons with
a different type of bulb than everyone expects.

I'm not sure I quite buy that. I think the equivalency is about right, but
you must run the bulb for five minutes before you make the comparison.

Christian.

"N. Thornton" wrote in message
om...
"Richard Blackwood" wrote in message
...

All a bulbs power input becomes heat: about 98% of it becomes heat
directly, the rest becomes light, which turns to heat less than a
microsecond later as its absorbed. The power input always equals the
heat output.

CFLs are the solution, but dont be caught out by the one issue: the
stated equivalent powers are unrealistic, as they are comparisons with
a different type of bulb than everyone expects. The real efficiency
improvement is about 3.5x - 4x, so to replace a 60w bulb you need a
15-17 watts.

If you trust the box's equivalency claims, its dimmer and doesnt look
right.


I must agree that the equivalencies do seem rather on the optimistic side,
to put it kindly.

Rick

"Grunff" wrote in message
...
Brian Sharrock wrote:

Sometimes; you have to switch ON a CF 'bulb' in the morning if
you want to read by it in the evening! OK! That's a slight hyperbole;
but they are slow to come to full brilliance. They are fine for
lamps which will be ON for hours ... but not for places where
the lights will be switched ON for short periods (toilets, bathrooms,
bedside lamps, for instance)


Again, I've found this to vary greatly between makes. Some are very
poor, taking 10mins or more to reach max output, while others do so in a
few seconds.


The time is actually programmed in by the manufacturer. Most now use the
STMicroelectronics chip and it is easy to set this from 1 second to days.
The slower it turns on the longer the tube will last.

G&M wrote:

The time is actually programmed in by the manufacturer. Most now use the
STMicroelectronics chip and it is easy to set this from 1 second to days.
The slower it turns on the longer the tube will last.


Well I'll be... I always wondered why they took so long to warm up;
never realised it was ramped!

Why does it affect longevity? I thought the only faliure modes were
driver failure and phosphor ageing.

--
Grunff

On 8 Sep 2004 07:44:22 -0700, N. Thornton wrote:

If you trust the box's equivalency claims, its dimmer and doesnt
look right.

Yep, been caught like that. I now look for the little box that gives
the techy information, like (but not always) voltage, fitting code,
life, lumens, colour temperature.

For example a 60W incandescant has "240V 700 Lumen 1000h" on the
bottom of the box. Morrisons (=A32.99 for 2) 11W CFLs have "711 Lumen 11=

Watt 12000h". I have yet to try these cheapies and I'm fully expecting
the colour to be crap...

You can get decent colour temperature CFLs now though, just replaced
6x40W E14 candles with GE Tech Extra Mini 9W CFLs, there is actually
more light in the room now. Not cheap, =A36.98 each springs to mind from=

B&Q, but as these lights are on for 18hrs a day the reduction in the
power bill will have paid for them in about 9 months...

--
Cheers
Dave. pam is missing e-mail

Grunff wrote:
G&M wrote:

The time is actually programmed in by the manufacturer. Most now use the
STMicroelectronics chip and it is easy to set this from 1 second to days.
The slower it turns on the longer the tube will last.


Well I'll be... I always wondered why they took so long to warm up;
never realised it was ramped!

Why does it affect longevity? I thought the only faliure modes were
driver failure and phosphor ageing.

You get the best life from a bulb if you turn the heater filliments on
some 1-2 seconds before actually starting the light.
If you don't, then the heaters get bombarded with ions and this dislodges
lots of their substance, which ends up on the walls of the tube.
With a tube that's working properly, the heater emits electrons, which
neutralise the ions before they get to the fillimnent.

The actual bit of the heater which does the work is in fact heated a bit
by the incoming ions reacting with nearby electrons, so runs a bit hotter
than due to the current alone.

Similarly with CCFLs, the unheated cathode actually gets hot, which does
similar things.
Both of these are a reason why dimming some fluorescant tubes may cause
blackening at the ends of the tubes and premature failure.

In article ,
"G&M" writes:

"Grunff" wrote in message
...
Again, I've found this to vary greatly between makes. Some are very
poor, taking 10mins or more to reach max output, while others do so in a
few seconds.

The time is actually programmed in by the manufacturer. Most now use the
STMicroelectronics chip and it is easy to set this from 1 second to days.
The slower it turns on the longer the tube will last.

You are referring to the preheat time (normally around a second).

The issue is the run up time, which is the time to get the mercury
vapour up to operating pressure. This is minutes, as it requires
heating the amalgam pelet to release the right amount of mercury,
and having it diffuse throughout the tube. This will vary with
the length of the tube, where the pellet is retained (if it's
retained at all;-), ambient temperature, how long since last run,
etc. There are also a few different ways to govern the mercury
pressure which various different manufacturers use.

Unfortunately, for small tubes which run hot and at widely
varying temperatures depending on luminare, no one seems to have
come up with a way to get them to operating pressure quickly.
For the traditional linear tubes which run warm and at a more
predictable temperature, they were simply dosed with the right
amount of mercury to run at 40C (25C ambient) without the need
for some means to keep the mercury pressure right over a wide
temperature range. So although they also have an appreciable
run up time, the light output difference at the start and end of
the run up is not normally as noticable, and if you run them at
the wrong temperature, the light output drop often didn't notice
either. They could be manufactured for alternate operating
temperatures, such as inside industrial freezers, or sleeved
to keep them warm but then you do notice the run up time from
very cold.

--
Andrew Gabriel

"Andrew Gabriel" wrote in message
...
In article ,
"G&M" writes:

"Grunff" wrote in message
...
Again, I've found this to vary greatly between makes. Some are very
poor, taking 10mins or more to reach max output, while others do so in
a
few seconds.

The time is actually programmed in by the manufacturer. Most now use
the
STMicroelectronics chip and it is easy to set this from 1 second to
days.
The slower it turns on the longer the tube will last.

You are referring to the preheat time (normally around a second).

0.8 second to be precise. But no, I was referring to the auto frequency
ramp up the latest chips provide which allows the lamp power to also be
ramped up independent of the mercury state, though of course this is done
primarily to allow the vapour to diffuse fully through the tube before full
power is applied. These bulbs are identifiable as when you switch them off
and on they still ramp up to full power, though at a faster rate than from
cold, whereas with previous generation devices the warm bulb will come on
full after the preheat.

In article ,
Ian Stirling writes:

You get the best life from a bulb if you turn the heater filliments on
some 1-2 seconds before actually starting the light.
If you don't, then the heaters get bombarded with ions and this dislodges
lots of their substance, which ends up on the walls of the tube.
With a tube that's working properly, the heater emits electrons, which
neutralise the ions before they get to the fillimnent.

The actual bit of the heater which does the work is in fact heated a bit
by the incoming ions reacting with nearby electrons, so runs a bit hotter
than due to the current alone.

Yes. Once the arc is established, supplementary cathode heating is not
required. (However, it does increase the cathode life slightly, but uses
more energy too.)

Similarly with CCFLs, the unheated cathode actually gets hot, which does
similar things.

Cold Cathode fluorescents don't rely on the cathode getting hot.
It would have to get to bright orange temperature before it started
becoming a thermionic emitter. They just operate with a higher cathode
fall voltage to get the electrons out of the metal (which is less
efficient than the conventional thermionic cathode tubes).
This also disloges the cathode material, but the electrodes are normally
formed from the inside of a cylinder, which means most of the disloged
material ends up sticking to some other part of the cathode and it doesn't
wear out very fast. The electric field inside a cylindrical electrode
doesn't increase as much, which also prevents the ions and electrons
picking up large energy just before they impact the surface. CCFLs
normally have a much longer life than conventional fluorescents because
of this. (The tiny ones used in scanners have much simpler cathodes
and a much shorter life.)

Both of these are a reason why dimming some fluorescant tubes may cause
blackening at the ends of the tubes and premature failure.

Circuitry designed for dimming fluorescents will provide supplementary
cathode heating at reduced arc current to ensure the cathode stays at
thermionic operating temperature. (Mostly dimming ballasts provide the
supplementary heating continuously regardless of the arc current.)

--
Andrew Gabriel

"Christian McArdle" wrote in message .net...
CFLs are the solution, but dont be caught out by the one issue: the
stated equivalent powers are unrealistic, as they are comparisons with
a different type of bulb than everyone expects.

I'm not sure I quite buy that. I think the equivalency is about right, but
you must run the bulb for five minutes before you make the comparison.

Christian.


theyre compared to soft light bulbs, which have lower light output
than standard GLS ones.

Unfortunately this dim practice is their downfall, as it has led to
the popular perception that their light is inferior.


Regards, NT

"Brian Sharrock" wrote in message
...

"Colin Wilson" wrote in message
t...
Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature.

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

Sometimes; you have to switch ON a CF 'bulb' in the morning if
you want to read by it in the evening! OK! That's a slight hyperbole;
but they are slow to come to full brilliance. They are fine for
lamps which will be ON for hours ... but not for places where
the lights will be switched ON for short periods (toilets, bathrooms,
bedside lamps, for instance)

--

Brian



I have them in our bed side lamps and they are much better than standard
lamps.

Steve Dawson

"Stephen Dawson" wrote in message
...

"Brian Sharrock" wrote in message
...

"Colin Wilson" wrote in message
t...
Yes, they will give out a lot less heat. The only problem with CFs
(compact fluorescents; what these are) is the colour temperature.

Not only that, some can take a while before they start to emit their
stated "equivalent" output...

Sometimes; you have to switch ON a CF 'bulb' in the morning if
you want to read by it in the evening! OK! That's a slight hyperbole;
but they are slow to come to full brilliance. They are fine for
lamps which will be ON for hours ... but not for places where
the lights will be switched ON for short periods (toilets, bathrooms,
bedside lamps, for instance)

--

Brian



I have them in our bed side lamps and they are much better than standard
lamps.


OK; Steve: lets parse your sentence: -
I said they (CF lamps) are fine for situations were the lamp
will be ON for 'ages' - you said that you use them at your bedside -
implication: I only switch on the bedside lamps for short periods
while you keep yours ON for longish periods.
As the sayiing goes YMMV!

I've not heard of anyone using standard lamps by the bed sides.
I agree with you that, for this purpose, bed-side lamps (either
table-supported or wall-hung) are better than standard lamps.

--

Brian

Christian McArdle wrote:

I'm having to get up several times a night to change nappies etc. at the
moment. The fact that you don't have a tear inducing, retina rupturing 100W
of light down your eyeball as soon as you turn on the light is excellent. My

I think it took about three days after getting our first sprog home
before deveoping a deep afection for dimmer switches; which got fitted
all over the place ;-)



--
Cheers,

John.

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Christian McArdle wrote:

but the newer ones with electronic ballasts run much cooler.


I should mention that it is quite possible to touch many types of low energy
lamp whilst still on. They are usually quite hot, but within the tolerance
of most people.

same is true for a 40w incandescent I find...

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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\================================================= ================/

same is true for a 40w incandescent I find...

You have a higher tolerance than me! 20W is about my limit...

Christian.

"John Rumm" wrote in message
...
Christian McArdle wrote:

but the newer ones with electronic ballasts run much cooler.


I should mention that it is quite possible to touch many types of low
energy
lamp whilst still on. They are usually quite hot, but within the
tolerance
of most people.

same is true for a 40w incandescent I find...

You're a chef ? Or an exhaust mechanic ? Or ... ?