the dimmer should bring the heat tape temp down.


it can be controlled with a dimmer but you need to play around with it more than you would if you used a thermostat.
keep testing it and it should eventually stop at your desired temp. just remember that when you dim the heat tape the enclosure will still need to reach reach its max heat(when the reading on your thermometer is constant). when that reading finally sets raise or lower the power to what you need to get proper heat.

its what i would do... hope i helped...