Thermostats – Their Importance and use.

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Microclimate B1 HT Digital dimming thermostats

Thermostats – Their Importance and use.

Thermostats are important, but why? Well, Reptiles and Amphibians are Ectothermic!
A fancy sounding statement, but probably one of the most important things you should know when keeping Herps.What this means is, unlike humans who generate body heat through various internal processes, Reptiles and Amphibians get their body heat from their surroundings, which in turn aids various processes, such as digestion and the Vitamin D3 cycle. This is where thermostats com in to play.
The warmer the environment is, the warmer the Herp will be. In their natural environment, there will be a myriad of different areas to go to, with varying temperatures which the animal can choose from. However, in the captive enclosure, these options will be slim, so it is important we maintain the temperatures very carefully, so as to not overheat, or cool, our beloved pets.These devices detect the temperature in the enclosure using a temperature probe. The thermostat then compares this figure, against the one desired, and controls the power going to the heating device to either increase, or decrease, the temperatures.

Types of Thermostats

There are 3 main types of thermostat, of which they can come in analogue or digital format, as follows;

On\Off Thermostat – This is the simplest of stats available, and is often called a ‘Mat Stat’ due its most common use being with heat mats.
The thermostat will be set to a temperature that is desired, if the enclosure temperature exceeds the set level, it will completely remove power from the heat source. Once the temperature drops to a sufficient level (within a certain percentage below the desired level) it will turn the heat source back on to full power.
Due to the On/Off nature of this device, it is not suitable for light emitting bulbs. However, it is suitable for Heat Mats, Heat Cable and Ceramic Heat Emitters (CHE’s), though will slightly shorten the lifespan of the latter.

Dimming Thermostats – This thermostat is suited best to light emitting bulbs, but can also be used on CHE’s.
These control temperatures by reducing power to the heat source, which dims it, to maintain a constant temperature, rather than fluctuating temperatures caused by the on/off thermostat.

Pulse Thermostats – A pulse thermostat works in a similar manner to an On/Off thermostat, by switching power to the heat source on and off. However, unlike the On/Off stat, a pulse stat continually cycles between on and off, varying the length of each cycle depending on the temperature of the enclosure.
If temperatures are higher than the preset limit, the thermostat will increase the time it is off and decrease the time it is on, and vice versa if the temperatures require increasing.

So why are they important?

You’ve bought your enclosure, set up the heating and used the perfect wattage bulb so the temperatures are perfect when you add your reptile.
You can now go to bed, satisfied that your pet is fine.
In the morning, you come down to find your reptile in the cool end, splayed out looking rather ill. It’s a much warmer day today than it was yesterday, so the ambient temperatures, both in your living room and more so in the enclosure, are much higher. But your bulb is still working at 100% capacity, further exacerbating the overheating in the enclosure
Or, on the other hand, it’s a much cooler day today.
Your little reptile is spending all day under the bulb, but inside, he isn’t digesting those cockroaches you fed him.

The problem is, your bulb is working at 100%, all the time, so cannot respond to any changes in ambient room temperature.
This is where a thermostat comes in handy.

By attaching a thermostat between the power source and your heat source, the temperature will be maintained, turning the bulb off or dimming it when the temperatures get too high, thus reducing the ambient temperatures.
To ensure you can control temps the other way too, it is important to use a bulb of a higher wattage than is required on an average day.
You bulb should work at 70 – 80% capacity on an average day in the home (When it is comfortable to sit in a T-Shirt).
That way, there is spare capacity to increase temperatures when ambient room temperatures drop.

When would you not use a Thermostat

Of course, there are always exceptions to the rules, and sometimes you can’t or won’t need to use a Thermostat on your heater.
Some experienced keepers with much larger than average vivariums or setups will opt to use a wattage of bulb that they know generates a certain temperature range. Because the enclosure is so large, the bulb will not affect the temperature in the cool end of the enclosure, so the inhabitant has space to regulate their temperature.
Also, some bulbs are not able to be put on a thermostat. Mercury Vapour Bulbs have to reach a specific voltage point to spark on and provide heat and UVB. Using a thermostat will prevent these from working and may even damage the bulb. Of course, that means MVB use should be limited to large or open top enclosures.


Thermostats are one of the most important parts of your enclosure, not only from a husbandry management perspective, but from a safety and cost efficiency one too. If you don’t yet have one, please do.

© 2015  Tarron Boon, Bioactive Herps

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