Ask 'Dr. Spa' Q & A Message Board

This trick will only work with light sources that are relatively inefficient at converting electricity to light, such as incandescent bulbs, halogen bulbs, etc. It will not work with highly efficient light sources such as LED lighting or fluorescent lighting.

In the case of incandescent bulbs, the efficiency is so low that approximately 90 percent of the electrical energy is converted to heat and only 10 percent or so is converted to light energy. In effect, we are deliberately harnessing the heat energy.

A pair of workmen's drop lights (caged type) with 60 watt bulbs will put out slightly more than 100 watts of heat energy (about 54 watts per light). When you consider that many hot tubs use 1000 watt heaters to get to and maintain 104 F, it is much easier to understand how 1/10 of that amount of heat will at least keep a tub from freezing (assuming the cover is left in place and the access cover is replaced in order to retain the heat as well as possible). You would certainly be unable to soak in the tub, but the temp could probably be maintained well up into the 30's and possibly even into the 40's, depending on the actual outside temps and how well the tub is insulated.

John

: Ok, I have read this idea of a light bulb keeping the equipment warm a
: few times lately...even had the Catalina rep tell me I could have
: prevented a freezeup with just a light bulb...

: Would you please explain to me how one small light bulb could have saved
: my tub from freezing up in below zero weather? Am I missing something
: big time here???

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