Zoo Med Analog Reptile Thermometer
Part no.
TH-20
Warranty
6 months
Temperature range
-6 to 49°C
Zoo Med Analog Reptile Thermometer
The cheapest insurance a heated enclosure can carry. The Zoo Med analog reptile thermometer (Zoo Med item TH-20) is a dial gauge reading -6 °C to 49 °C, mounted to the terrarium wall with hook-and-loop backing so it can be repositioned as the enclosure changes. It tells you the air temperature at the exact spot it is stuck – which is the number you need at the cool end, in the hide, and at the animal's resting height.
Reptile enclosures are not one temperature. They are a gradient, and the gradient is the whole point: the animal moves along it to regulate itself. A single gauge tells you one point on that gradient, so where you put it decides what it is worth.
Key features
- Reads -6 °C to 49 °C – covers a cool-end winter low and a Queensland summer high without pinning at either end of the dial.
- Hook-and-loop backing – moves to a new spot without adhesive residue, so you can chase the gradient instead of committing on day one.
- No power, no batteries – nothing to go flat unnoticed, which is the failure mode that makes a digital gauge dangerous when you stop checking it.
- At-a-glance dial – readable from across a room, so a daily check costs a second rather than a stop.
- Cheap enough to run several – one gauge gives you a number; two, at each end, give you the gradient.
Specifications
| Zoo Med item number | TH-20 |
|---|---|
| Our SKU | ZM13 |
| Barcode | 097612300208 |
| Measures | Air temperature |
| Range | -6 °C to 49 °C (20 °F to 120 °F) |
| Display | Analog dial |
| Mounting | Hook-and-loop (Velcro-style) backing |
| Power | None – no battery |
| Manufacturer warranty | 6 months |
What this gauge does not measure
An analog dial thermometer reads the air temperature at the point it is mounted. It does not read basking surface temperature, and the two are not close – the surface of a basking rock under a spot lamp routinely sits well above the air a few centimetres away.
If you need the basking surface figure, you need an infrared temperature gun pointed at the surface itself, or a probe laid on it. Use this gauge for the ambient gradient and a gun for the hot spot.
It is also not a controller. A gauge tells you the temperature after the fact; it cannot switch a heat source off. Every heat mat, ceramic emitter and basking lamp needs a thermostat of the correct type wired between it and the power point. Running a heat source unthermostatted because a thermometer is fitted is the most common cause of burns and heat stress in captive reptiles.
Where to mount it
| Position | What it tells you | Worth doing? |
|---|---|---|
| Cool end, at animal height | Whether the cool end is genuinely cool enough for the animal to escape the heat | Yes – the most important single reading |
| Warm end, at animal height | Ambient warm-end air, not the basking surface | Yes – pair with the cool-end gauge for the gradient |
| Inside the hide | The temperature the animal actually spends most of its day in | Yes, if the hide is large enough |
| Directly under the basking lamp | Radiant heat on the gauge body, not room air – reads high and misleads | No |
| On the glass in direct sun | Solar gain on the gauge, not enclosure air | No |
Suitable for, and not suitable for
Suitable for: glass and PVC terrariums, snake tubs and racks, bearded dragon and gecko enclosures, tortoise tables, amphibian and invertebrate setups – anywhere you want a permanent, unpowered read on ambient air.
Not suitable for: measuring basking surface temperature, measuring heat mat surface temperature, submerged or in-water use in an aquatic turtle tank, or as any part of a temperature control system. It is also not the gauge for someone who needs to know the overnight low while they were asleep – that is a job for a min/max recording thermometer.
Which Zoo Med gauge do I need?
| Gauge | Measures | Reads out | Choose it when |
|---|---|---|---|
| Analog Reptile Thermometer (TH-20) | Temperature | Analog dial, no battery | You want a permanent unpowered temperature read at one point |
| Analog Humidity Gauge (TH-21) | Humidity | Analog dial, no battery | Humidity is the parameter you are chasing, not heat |
| Digital Min/Max Thermometer | Temperature, with recorded highs and lows | Digital, battery | You need to know the overnight low or the daytime peak you were not there to see |
| Creatures Dual Hygrometer & Thermometer | Temperature and humidity | Single unit | You want both parameters from one mounting point in a small enclosure |
| Creatures Digital Thermometer | Temperature | Digital, battery | You want a numeric read rather than a dial |
Care and maintenance
Keep the dial face clear of substrate dust and condensation; a fogged face is the usual reason a gauge stops getting read. Wipe with a dry cloth, not a solvent.
The hook-and-loop backing loses grip when it gets damp or dusty. In a high-humidity enclosure expect to replace the pad occasionally rather than the gauge.
Goes well with
- Zoo Med Analog Humidity Gauge – the matching dial for the other parameter that matters, mounted alongside.
- Zoo Med ReptiCare Ceramic Heat Emitter – the kind of heat source this gauge exists to keep an eye on.
- Zoo Med Repti Rock Water Dish – water placement shifts the local humidity and the cool-end temperature together.
- Zoo Med ReptiSun T5 HO 10.0 UVB Tube – lighting and heating get planned against the same gradient.
Warranty and delivery
Zoo Med publishes a 6 month warranty on this gauge. That warranty is in addition to your rights under the Australian Consumer Law, which are not limited by it.
Standard freight. Small, light, no dangerous goods or oversize handling.
Common questions
What temperature range does the Zoo Med analog reptile thermometer read?
The Zoo Med TH-20 analog reptile thermometer reads from -6 °C to 49 °C, equivalent to 20 °F to 120 °F. That span covers a cool-end winter reading and a hot summer day at the warm end of a typical Australian reptile enclosure.
Can I use it to set my basking spot temperature?
No. This gauge reads air temperature at the point it is mounted, not the surface temperature of a basking site. Basking surface temperature has to be measured with an infrared temperature gun aimed at the surface, or a probe resting on it. Use the dial gauge for the ambient gradient instead.
Does it replace a thermostat?
No. A thermometer reports temperature; a thermostat controls it. Every heat mat, ceramic emitter and basking lamp in a reptile enclosure needs a thermostat of the correct type between the heat source and the power point. The gauge is how you verify the thermostat is doing its job.
How accurate is an analog dial gauge?
Zoo Med does not publish an accuracy figure for the TH-20, so treat the reading as indicative rather than laboratory-grade. It is reliable for the job it is bought for – seeing at a glance whether the gradient has drifted – and for setting a thermostat you should confirm against a second instrument.
How many should I fit to one enclosure?
Two is the sensible minimum in any enclosure with a heat source: one at the cool end and one at the warm end, both at the height the animal actually sits. A single gauge tells you a number; a pair tells you the gradient, which is what determines whether the animal can thermoregulate.
