Re: [APD] DIY Metal Halide Fixture

[Shalom Levytam <shalominc at yahoo_com>]

Thanks for your reply,

I am going to try your suggestions tonight and
hopefully things will work out.  I like the idea of a
ceramic pad to protect the finish, so I am going to
hunt for that.

Thanks again,

Shalom

--- "S. Hieber" <shieber at yahoo_com> wrote:

> Remember that MHs do not put out more heat wat for
> watt
> than a fluorsecent bulb -- it's just concentrated in
> a
> smaller area. So the key is spread out the heat and
> carry
> it away from the wood.
> 
> If it was me then I would:
> 
> Use glass for shielding instead of plastic this is
> an
> excellent example of when glass is much better than
> acrylics.
> 
> Use a larger piece of metal for the bracket so that
> it will
> disperse the heat energy over a greater mass and
> large
> volume. However, if the metal is very short (i.e.,
> the bulb
> is very clos to the wood), then the wood will be
> getting
> about as hot as the metal even without the bracket
> attached. So, I would space the reflector away from
> the
> wood and provide plenty of ventilation on both
> surfaces of
> the reflector. If you are using a fan, have some of
> the air
> flow over the top of the reflector between the
> reflector
> and the hood.
> 
> Also, you can get a ceramic pad (they used to make
> them out
> of asbestos but not any more) that plumbers use to
> protect
> wood in the house walls when they are using a
> propane torch
> to sweat copper pipe fittings. These are usually
> about
> 8-12" square and you can find them at Home Depot and
> similar joints. Affix the pad to the wood (with some
> screws
> that are too short to go all the way through the
> wood)
> directly over the bulb location. This will help
> retard the
> passage of energy into the wood faster than the wood
> can
> shed the energy -- but ventilation will still be
> required
> for this insulation to help much.
> 
> I think the flash point for most woods is a tad more
> than
> 600F. The outer bulb surface temperature is possibly
> not
> more than about 350F and very likely less than 500F.
> Still,
> if too much heat is located in too small an area,
> you will
> dry and age the wood prematurely.
> 
> If you get an inch or so away from the bulb and
> provide
> some ventilation, the wood should not reach an
> unreasonably
> high temprature.  However, I believe the finish on
> the wood
> will probably prematurely age if the temperature of
> the
> finish is much more than about 150F-180F, depending
> on the
> finish.
> 
> Hope that helps,
> Scott H.
> 
> --- Shalom Levytam <shalominc at yahoo_com> wrote:
> 
> > Hello,
> > 
> > I have finally gotten a chance to complete the
> > lighting for my tank; however, I have run into
> some
> > problems which I am hoping someone could help
> with.
> > 
> > The setup is currently an aluminum reflector that
> > almost looks like a roof with the middle portion
> flat
> > and the sides at 45degrees down.   The socket is
> > mounted sideways within the reflector.  A metal
> strip
> > attaches to the top of the reflector and is used
> to
> > mount the reflector to the wooden canopy. 
> Finally, a
> > piece of acrylic is used as a water shield for the
> > reflector.
> > 
> > Two big problems!  First, the metal strip mounting
> the
> > reflector gets TOO hot!  I am worried that it
> might
> > catch the wood on fire by some misfortune. 
> Second,
> > the acrylic sheets I used as a watershield have
> > started to melt.  I only had the light running for
> 30
> > minutes.  
> > 
> > Does anyone have a suggestion as to better
> materials
> > or methods.  The lights are mounting really close
> 2-3
> > inches from the water so I think i need a
> watershield.
> > 
> > Thanks,
> > 
> > Shalom
> > 
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> 
> 
> =====
> --- Christel Kassellman is returning to America! ---
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> attend. 
> 
> March 18-20, 2005
> Marriott Hotel, Farmington, CT
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