Thermostat Rheostat?

[Seijin]

What is the difference between a thermostat and a Rheostat?

[surfimp]

Hey now! The main difference between a thermostat and a rheostat can be described this way: a thermostat is "active" while a rheostat is "passive".

A thermostat takes constant temperature readings via an external probe. When the temperature measured at the probe falls below a certain temperature set point (programmed or mechanically set into the thermostat), the thermostat starts powering your heating elements. When the heating elements raise the temperature to the desired set point (as measured at the probe), the thermostat cuts off power to the heating elements. If the temperature drops back down below the set point, it will start powering the heating elements again.

A rheostat, on the other hand, does not monitor temperature. Instead, it provides a steady amount of power to the heating elements, according to how "high" or "low" you've set the power. The power supplied to the heating elements will stay constantly at this set level (assuming your power doesn't go out), and it's up to you to determine (using thermometers throughout your enclosure) what power level (i.e. high medium low etc) provides you with the thermal gradient that you're looking to create.

The upside to thermostats is that they are "fire and forget", more or less; once you are finished tinkering with your heating setup, they will diligently work to maintain that setup to the best of their abilities and this will (theoretically) result in a constant, stable temperature for your snake's enclosure.

Rheostats are capable of providing the same sort of stability, assuming that the room in which you have your snake enclosure does not vary in temperature by any appreciable amount. However, if the room gets very hot (on a warm day, for example), the rheostat will continue to pump out whatever amount of heating you've "dialed in"; this can result in dangerous over-heating situations which can literally cook your snake. So the downside to rheostats is that they do not adapt to changing conditions and can be somewhat more risky for your animals (unless you are constantly monitoring temperature to prevent catastrophe--which you should of course be doing no matter what, but it becomes somewhat more critical when using rheostats in my opinion).

I strongly endorse the use of thermostats because they provide you with much greater piece of mind, in my opinion. They do cost a fair bit more than rheostats, but they are purpose-built for the task (as opposed to "jury-rigged" dimmer switch setups) and should last for years. For myself, I use Helix Controls products and love them; they are sort of "industry standard", especially for breeders (although some people use different products and love them as well). Before purchasing my 'stats from Helix, I did quite a bit of research into all of the various heat control options and I came to the conclusion that they were best. If you're interested:

http://www.helixcontrols.com

Hope that helps and good luck!