Which Thermostat Should I Choose?

One question which we get asked a lot, is which thermostat should be used with which heat source? This article will help you decide which is the best thermostat for you and your animals and when each type of thermostat should be used and why.

There are three main types of thermostat available to use with reptiles and other animals. These are On/Off Thermostats, Pulse Proportional Thermostats, and Dimming Thermostats. Each Works in a different way to control the temperature, and is suitable for different applications.

On/Off Thermostats

These thermostats are the cheapest and are suitable for controlling heatmats, heat cables and other similar heat sources which provide contact heat.

They work by checking the temperature at the thermostat probe at frequent intervals, and then either turning the heat to the thermostat on or off depending on the temperature. Once the temperature at the probe reaches the temperature set on the thermostat controller, it will turn power to the heat source off, and when it drops below this temperature, it will turn back on.

To be effective, the thermostat probe ideally needs to be in contact with the heat source (e.g. the heatmat). Putting the probe anywhere else in the vivarium will not allow the thermostat to maintain the heat source at the set temperature accurately.

Because of their on/off nature, these thermostats are not suitable for controlling light emitting heat sources such as bulbs, or for controlling ceramic heat emitters, as they have a tendency to blow the bulb frequently and also turning the light on and off regularly may be disturbing to your reptile.

Pulse Thermostats

These thermostats are great for controlling non light emitting heat sources such as ceramic heat emitters/bulbs. They are also suitable for more accurate control of heatmats where precise temperatures are important, such as in incubators.

They work by constantly checking the temperature at the thermostat probe, and by changing how frequently pulses of electricity are sent to the heat source. If the temperature at the thermostat probe is too hot, then the frequency of electrical pulses to the heat source will be decreased, if the probe is too cool, the frequency of electrical pulses to the heat source will be increased.

To be effective, the thermostat probe should be positioned at the spot where the temperature set on the thermostat is desired, preferably within direct line of sight of the heat source (e.g. ceramic bulb). This allows an accurate temperature to be maintained at the thermostat probe.

Because of the pulses of electricity used to maintain an accurate temperature, these thermostats are not suitable for controlling light emitting heat sources such as light bulbs. If used with a light emitting source, they cause flashing of the light and tend to blow the bulb frequently.

Dimming Thermostats

These thermostats are more expensive, but are the only effective way to control light emitting heat sources such as light bulbs. They can actually be used to control pretty much any source of heat, and are the most accurate at maintaining precise temperatures.

They work by providing a 'sliding' amount of electricity to the heat source, which causes a light emitting heat source to 'Dim' up and down to maintain temperature. If the temperature at the thermostat probe is too hot, then the amount of electricity supplied is decreased and the bulb dims. If the temperature at the probe is too low, then more electricity is supplied, causing the bulb to get brighter and therefore increasing the heat provided.

To be effective, the thermostat probe should be positioned at the spot where the temperature set on the thermostat is desired, preferably within direct line of sight of the heat source (e.g. light bulb). This allows an accurate temperature to be maintained at the thermostat probe.

Although these thermostats can be used with practically any heat source, it is usually more cost effective to use these for light bulbs, and other types of thermostat for anything else.

At A Glance

For Heatmats/Cables use an On/Off Thermostat
For Ceramic Bulbs/Accurate Heatmat Temperatures use a Pulse Thermostat
For Light Bulbs use a Dimming Thermostat


Always check that the thermostat you use is suitable for the wattage of your heat source. On/Off stats usually come in either 100W or 300W, and Pulse/Dimming Thermostats are usually rated to 600W.