Dimming vs. Proportional Thermostat?

[Rickys_Reptiles]

Traditional On/Off (Non-Proportional) Thermostats
Before we talk about proportional thermostats, you need to have a basic understanding of how a regular thermostat works.
In a nutshell, a typical thermotat will monitor the temperature using a thermocouple or probe attached by a wire. When the probe tells the thermostat that the temperature has reached one degree (or whatever the case may be) above the desired temperature, the thermostat will cut power to the heating device, turning it off. When the temperature drops back down below the desired temperature, the thermostat will turn power back on to the heating device. It's a very simple idea - if the temperature needs to go up, power to the heating device is turned on. Once the desired temperature is met or exceeded, it is turned back off. That being the case, the heating device is either getting full power or no power at all. This type of thermostat is best suited for heating devices that work in a strictly on/off fashion.
Proportional Thermostats
Similar to a traditional thermostat, a proportional thermostat has a probe that tells it when heat needs to be applied or turned off. Unlike a traditional thermostat, a proportional thermostat works like a dimmer in that it can adjust the amount of voltage being applied to the heating device. But it's better than a dimmer because it can measure the temperature and it knows exactly how much power needs to be applied to the heating device to maintain the desired temperature.
As a general rule of thumb, if a heating device works in a strictly on-or-off fashion, it will not run without a set amount of voltage. As such, proportional thermostats cannot operate things like the furnace in your home, or even a space heater, because those devices need full power from the wall outlet in order to function. However, heating devices that we commonly use in the reptile hobby, like heat pads, heat panels, heat rope/cable, heat tape, ceramic heat emitters and even incandescent light bulbs, can be operated by a proportional thermostat. With these types of heating devices, a proportional thermostat may be your best option.
Pros...
Gentle Warmth
By applying just enough voltage to the heating device, you're providing a more uniform, gentle warmth. This is because the heating element (tape, pad, cable, etc.) is constantly running right at the desired temperature, rather than bouncing back and forth between full power and no power.
Longer Lived Heating Devices
With an on/off thermostat, the constant on/off action causes more wear and tear on devices meant to be run on dimmers like heat pads, heat tape, heat cables and especially light bulbs.

Cons...
Proportional thermostats will not run a furnace, space heater, etc.
The only downside to pr oportional thermostats is that because they work by applying varying amounts of electricity to the device they're controlling, they generally will not run certain types of heating devices.
*Remember, I said MOST...
Spyder Robotics makes an entire line of proportional thermostats that also have a "Non-Proportional" setting which allows them to be used as a standard "on/off" thermostat. These units are quickly becoming my thermostat of choice for python enclosures...industry leading technology and still competitively priced. Apples to apples, these things are a steal.

reference: http://www.acreptiles.com/