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Re: MHD Lights and Westerners

Ivo Busko wrote:
> > Alfred Heng <alheng at pacific_net.sg> asked:
> > > "How much heat does MHD lamps generate?"
> I wrote:
> > [snip] 300 watts of MH generates the same heat as 300 watts of
> > FL lighting.
> I understood that the question refers to "how much heat a MH lamp releases
> directly to the ambient". As you said, every single watt of electricity
> consumed by a lamp fixture ultimately ends up in the form of heat, either 
> as direct heat emission by the bulb/ballast, or as light absorbed and 
> re-emitted as heat by the objects illuminated by the fixture (except, 
> as you already pointed out, the small amount that goes into chemical 
> conversions in plants). But the "light / direct heat" ratio provided by
> different types of bulb can be very different, as in between fluorescents
> and incandescents. 
> Or did I entirely miss the point here ?

You got the point and so did I, I do believe.

The rule of ambient heat production is the same for incandescent as it
is for FL. There's a lower ratio of visible light with incandescent but
even that light ends up being absorbed by what it strikes and converted
to heat. An MH or incandescent produces a small point source of heat
whereas a FL tube produces a long and diffuse source of heat (the same
as the light source). The TEMPERATURE of the source is higher (but
smaller) and that is a different question than "what is the amount of
( heat = power ).

The efficiency of a bulb at producing light is a measure of the ratio
visible radiant energy to nonvisible (primarily infrared or radiant
heat). I believe only a tiny fraction might be produced in the ultra UV.
For FL and MH, this ratio is nearly the same although MH can put more
into the UV or near UV spectrum.

Sorry for the physics lecture. ;-)

Incidentally I do consider myself a true Westerner being born in
Alberta. Saskatchewan and Manitoba are still out West in my book. Being
Western is being from that part of the country where they rode horses
and drove cattle. Now they drive pickups. BC might be on the West Coast
(which is the proper name for it) but folks there ain't Westerners. West
Coasterners were loggers, gold panners and later, miners.

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!