Tank temp usually higher than source?

[Kroberts10]

I'm curious about something. Is it normal for the hot spot in the tanks to be higher temp than what the heat tape is? I'm running a plywood rack heated with THG tape controlled with a Herpstat 1 with the probe taped directly to the heat tape in the middle of the rack. The thermostat is set at approximately 87*F and the hotspots in the tanks run about 90-95* depending on the day. The substrate is paper towels and the thermometer probe is glued down to the inside bottom of the tubs. I don't have any issues with it, since my three balls will spend time on both the hot and cold sides with a majority being in the cold side. but was just curious if this was normal. It just seems odd that with a little air gap around the heat tape and tub that the tubs get several degrees warmer than the tape.

Thanks,
Kyle


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[JodanOrNoDan]

Assuming that your probe is below your heat tape the reading below your heat tape would be lower than the reading above it however it is impossible for the tub to be actually hotter than its heat source.

[Kroberts10]

That's what I was thinking. The only thing I can think of, is that where I have the probe it get a good air flow over it so is constantly putting out heat. And the inside of the tub,, especially under the paper towel, is insulated still air, so builds heat. But it still doesn't make much sense. I'll take a picture of my setup tonight and see what your all's thoughts are. And the thermostat is almost never at a steady state of output. It's almost constantly fluctuating from 0-20%


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[Kroberts10]

This morning I decided to try moving the thermostat probe from sitting on the heat tape on the side of the rack where is snakes up to the next slot, to under on of the tubs and the temperature quickly shot up to about 90*. So I guess that the temperature under the tubs was a good 4* or so hotter than the tapes temp on the side of the tub. Here's a picture of the setup. You can see the black probe wire going into the side of the rack. It was taped to the wall, now it's under the tank. I definitely learned to not use cheap plywood for a rack again. Two of the boards warped enough that I won't be able to use the tubs verry well. So I put the probe under one of those tubs. It should make for a good way of controlling the temperature by leaving a tub undisturbed on the probe. The other will be an easy fix when I need it.

Kyle


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