Reptile & Amphibian Forums

i'm not sure if this is the appropriate forum for this question but if it's not then i don't know what is . . . is there any kind of equation to derive the temperature increase (per cubic foot or whatever) per watt of a heat bulb? ed

I think there are too many unknowns to use any kind of formula. Whatever the bulb is shining on would help distribute the heat. So what it's shining on, how far away it is from what it's shining on, the amount of space being heated, these would probably all play in some how.

I'm going to elaborate a bit on what bryan said.

The first factor you have to look at is what kind of bulb is it? Is this just a regular incandescant filled with argon gas? Or is it a halogen, mercury vapor, or what? Each different type of bulb will produce different amounts of heat per watt used.

Then you have to look at what kind of reflector is on it? Is there a reflector built into the bulb, such as a spot bulb? Is there a dome reflector around the bulb? If there's one around it, then if it's ever so slightly different from another, this will adjust the refraction of the light and heat, thus changing your temperature.

Now what will it shine through? Just a screen top? Or plexiglass? It won't go through plexiglass well at all, and a 1/8" mesh will block more than a 1/2" hardware cloth will. (not a noticable amount, but some nonetheless.)

What is your enclosure made of? Glass and expanded pvc will losing a lot more heat than a 3/4" wood cage will. The coating on it will also minimally effect the insulation properties. Do you have any insulation around the tank? Vents (# and size and location)? Types and amounts of doors? Insulation around doors?

the list goes on and on. The best thing is to get a medium to large wattage bulb and put it on a rheostat, or a dimmer.
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