Quote Originally Posted by The Serpent Merchant View Post
Do you even know how proportional thermostats work? There are no "switches" envolved.

On/offstage thermostats do use relays, so yes over time they will wear out, but they are considerably cheaper.

The temperature of a resistor is greatly influenced by the ambiant temperature around it. So unless the room stays constant the temperature of a UTH will change. Zoo-Med themselfs admit that a thermostat is necessary in rooms over 80 degrees. That proves that the temperature is dependent on the ambiant temperature.

Look to be within the safe/ideal range you have to lower the temperature of a UTH by at least 30 degrees. No single pane of glass or sheet of plastic commonly used in the reptile industry is capable of that, heck my cages that are made of 1/2" thick PVC can't do that.

A proportional thermostat varies the temperature slightly, even the cheaper pulse proportional thermostats and high end on/off style thermostats do this. Large temperature swings aren't great, but the point of a good thermostat is to keep the temperature constant. So there isn't going to be more than a few degrees in temperature flux.
if they can turn on and off, they use some variation of a current interrupting device (aka a switch). A relay is essentially a switch that cuts a power source when another source causes it to.(or vice versa)