Not my area at all, but a dimmer IS NOT a stat. A stat is set at a temp and in some manner, usually a probe (for herps) to sense the temperature and tell the stat to turn heat unit on and off.
Dimmers just set an amount of resistance in the dimmer, (or voltage reg dimmers),,,, although AC is reactance, AC is in RMS (root means square)is the AC equivilennt to DC heat. So, AC is basically DC when resistance is all that is involved.
So, a dimmer just turns up to a set amount of voltage. So if external temperatures change the cage temp will to.
I use a bio stat. Simple, and up til recently very good. Most simple stats are like your home heating stat. Set it at 80, it may turn on at 81 and off at 79. A proportional stat, is far more accurate by not turning completely on and off. If again, you set at 80, and temps reach 79.5 it may turn on 50%, in an attempt to reach the goal set at 80, then if the temps still drops to 79.25, it goes to 75% of power (voltage really). Just an example
Proportional stats are great, but pricey. Cheap bi-metal or worse old mercury type stats (come on, ya know a few of you guys use an old Honeywell), are probably the least accurate.
IN far less words:
Proportional stats are best in general but expensive.
A thermoSTAT of most kind will work, with various degrees of temp control.
A dimmer IS NOT a stat.

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Thanks for reading.
Big Tom
www.HerpZillA.com
www.HerpHelp.com