# Exo Terra Vivariums - Heat Mats / Cracked Glass



## burrow (Nov 5, 2007)

I've heard loads of people saying not to use a heat mat inside the exo terra glass vivariums, only underneath as it may crack the glass.

What i don't understand is, if it's on a thermostat and isn't going to get any higher than 31oC - HOW will it get too hot and crack? You can put boiling water in a glass and it won't crack - it only does so when it cools down very rapidly.

ALSO i thought i'd download the habistat heatmat PDF from the website to see what it says. It states that with *GLASS* VIVARIUMS you can either use it underneath OR inside. 

It also states under the section "*Glass Tank Precautions" -* If the mat is being used under a glass tank, the substrate must not be too thick, because if it is, the heat will not transfer through, but overheat the glass and therefore crack it.


Basically, alsong as the substrate isn't too thick, the heat will just pass through warming up your beloved reptile. It will only crack if the substrate is too thick and is blocking the heat, therefore there will be a build up.


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## Drummerkid (Sep 24, 2007)

I think its okay, inside if your using kitchen roll. But id put the tank on top of some polystrene just to be safe. B&Q do sheets for a few quid.
JMO.


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## LFG (Apr 2, 2007)

Just a personal experience... (copied from my post on bugnation)

Several weeks ago I purchased a Hagan 25W 'Desert' heat mat from my local pet shop. The 25W heaters do get very hot, so I was using ventilation in between the mat and the base of tanks, which were only ever half on the mat.

Yesterday I discovered a hole burnt through the mat with charred edges, and scorch marks on the surface below. It was clear this had been hot enough that had something flammable been nearby it would have gone up in flames. The mat was no longer producing any heat when plugged in.

Having taken the heat mat back to the shop where I bought it, several calls were made and the following resulted:

- All similar heatmats were withdrawn from sale.

- Hagan stated over the phone that the backing MUST be removed from these heat mats (it covers a sticky side, and i didnt want it to stick to anything so left the plastic on). This may have contributed to the problem.

- Hagan have accepted the item was faulty, and are replacing all heat mats in that shop.

Please note this is *not* a problem with the smaller models, which run at up to 15W. This does *not *mean that other similar or identical models are dangerous, this is likely to be a one-off.

However, I would advise extreme care in choosing none-flammable surfaces for these mats to ensure if anything does overheat, the risk to life and property is minimal.

Matt


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## Beezle (Aug 26, 2007)

I use an exo-terra viv with a heat mat and the way I avoid any glass cracking is by using cork tiles (found in hardware and some stationery shops) or a large, cheap, cork notice board. Put a double layer in the bottom of the viv and sandwitch the heat mat in-between. The cork is good at conducting the heat upwards into the tank and acts as a heat spreader taking the hot spots away from the glass. Also, as an added bonus the cork layer will be splash proof, prevents direct contact with your animal(s) and the heat mat and it's fire resistant too. This is just my 2 cents but it works a treat for me


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## Scales and Fangs (Mar 22, 2007)

burrow said:


> What i don't understand is, if it's on a thermostat and isn't going to get any higher than 31oC - HOW will it get too hot and crack? You can put boiling water in a glass and it won't crack - it only does so when it cools down very rapidly.


The heat mat will get considerably higher than that, the thermostat isn't reading the temp of the mat, it's reading the temp of the air in the enclosure, just like the rads in the home, they get really hot, much hotter than the air arround them.

Hope this makes sence.

Rob


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## Rainwater (Apr 18, 2007)

well if its happened to other people then im not one of them...the exo terras were made to have mats in therefore the glass really shouldnt crack. ive had a heat mat in mine and it didnt crack, worked very well too.


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## burrow (Nov 5, 2007)

Yeah that's what i mean, they were designed for this, and on the habistat heat mat instruction it says that you can put it inside and the only risk of the glass cracking is from overheating by putting it UNDER the glass and having too thick a substrate so the heat just builds up.

I might just by some cork tiles to put under the mat to prevent any risk.


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## _simon_ (Nov 27, 2007)

I use a 16watt mat on the outside of my exo terra and so far it's been fine. I even use an 8watt on a plastic tank without problems.


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