Thermostats are a vital piece of equipment for keeping reptiles – not every species will require one, but most do. They will allow you to control the heat that is created in the environment, which means not only will you be able to set the temperature and know it’s perfect for your pet, but it’s also a safety feature – it can’t overheat and cause stress to your pet, or do any damage to the enclosure itself. Safety and peace of mind are invaluable.

Types of thermostat

There are different types of thermostat, and that’s where people tend to get confused. Different heating equipment will require different types of thermostat, keeping them functioning properly. As a rundown, we can look at the main types, and the best heat source used with each.

Firstly, the most basic is an on/off thermostat, or Mat Stat. This basically turns something on or off as it reaches the set temperature. This is best used with a non-visual heat source – a heat mat, or a heat cable or ceramic, though this isn’t the best for you. Although it will work with a light bulb, it will be constantly turning it on and off, which as well as being super irritating, will cause the filament to blow much earlier than it should. Not only will it annoy you and your pet, constantly going off and on, but you’ll replace the bulbs an awful lot more than you should have to.

The next setup is a pulse proportional thermostat, which sends electrical pulses to the heat source, and intensifies these or reduces them to control the temperature. Again, this shouldn’t be used on a visual light bulb, but is much better suited to ceramic heat emitters and heat cables. This will alter its pulses to ensure the temperature stays exactly where you want it.

The more sophisticated thermostat is the dimming stat. This can be used on light bulbs, and will literally dim the power to the bulb, meaning the light coming off it goes dim, and so the heat coming off it dims too. The important thing to remember when using this type of thermostat is that you still need the right bulb – a wattage too high will mean the bulb is constantly dimmed right down, or off, and so the light going into your enclosure will be diminished. Using a lower wattage bulb, that is occasionally dimmed, will be much better.

So ideally:

  • On/off or mat thermostat – heat mats
  • Pulse thermostat – heat cables or ceramic heat emitters
  • Dimming thermostat – visual light heat bulbs

Each thermostat will come with its own maximum wattage of power that can be run through it – make sure to check your heat source is compatible. Most on/off stats have a maximum wattage of 100w or more, so running an average sized 20-30w mat will be no problem at all. Dimmers tend to have around a 600w capacity.

Some people choose to use one thermostat across multiple environments, which providing your heat sources are the same, and the requirements for each are the same, shouldn’t be a problem. Choose a central enclosure ideally to run your probe, and check the others regularly to ensure the small variances in temperatures are suitable, as obviously setting the bottom of a stack of vivariums’ to 28C for example, means the top one will always be hotter, as heat rises.

Moving on from the more basic thermostats is when it can get complicated. Most models have the option of a “High Range” option, meaning the top temperature is higher, so more suited for desert species such as Bearded Dragons and Uromastyx, so be sure to check the maximum temperature your thermostat can provide. Most also have a “Day/Night” feature, wherein they can allow for a hotter daytime temperature, and adjust down for a lower nighttime temperature, more in keeping with your reptile's natural habitat. Be sure to check if your thermostat has built-in night/day capabilities, or whether an optional extra unit needs purchasing in order to use this function.

Digital thermostats

In recent years technology has brought us digital and touch screen thermostats, which can provide multi-use functions – such as being able to dim a heat bulb during the day, whilst then being able to run a pulse stat on a ceramic heater overnight for background ambient temperature. These have built-in timers as well, so will turn anything on or off at your desired times – the all-in-one package really.

A more unusual type of stat is one that controls humidity as well, by plugging in your chosen humidity source, such as a mister, and once the humidity drops below a set level is will turn it on to ensure your rainforest species are kept adequately.

With any type of thermostat, there is some debate about where to place the probe for controlling the device. The truth is there are different options, and some will suit better than others for your chosen set-up.

The first example is that the probe is placed underneath the heat source it's controlling – in the closest place a reptile could get to it – so the substrate for ground-dwelling species, but perhaps a tree or branch for arboreal species. This will then control this hot spot – so you set it to your chosen temp – say 38C, and it will ensure that spot stays at 38C. This means that further away from this spot, it will be cooler. It is advised to have thermometers at opposite ends to ensure you can check your gradient regularly.

The other way of setting these up is to do it the other way around – keep the probe in the coolest place, and set that to the coldest temp you require, say 22C. You know then that the cold end will always be cool enough for your pet to retreat from the heat if it needs to, and your other end will be a lot hotter.

As said, either of these techniques require that you are using thermometers to regularly read and check the opposite end, as your thermostat cannot create your gradient, merely control one area where the probe is. If you use the probe at the cool end, and the hot end isn’t warm enough, use a high wattage heat source. Similarly, if you use the probe on the hot side, and the cool end is too warm, use a lower wattage heat source.

In short - there is something for everyone. Except for Mercury Vapour Bulbs. There's nothing for them.