Heating a plastic viv?

[SquishyPenguin]

Hi guys! I was referred here by a friend, maybe some more experienced people can help out a first time critter owner.
I recently got my hands on two female hissing cockroaches, my house stays at about 21C all year so it's not deathly cold for them, but it's definitely in the lower temperatures.

I have a plastic critter keeper, but I'm having some serious issues heating it.
It's an Exo Terra PT2310 Flat Faunarium, it's all plastic. Measures 45.72 cm length by 30.48 cm width by 16.51 cm height.
My goal is around 25C to keep them at a more comfortable temperature

I've tried heat mats and they're not working. Everyone I ask says "use a heat mat" but I've wasted £40 on two different mats and neither has helped by more than 1 degree.
First mat I tried was an oversized Komodo heat mat, placed on the side of the tank as flush as I could get it (which was not at all, really).
Second mat I got from my local reputable store and was much smaller, sits completely flat against the plastic and covers about 50% of the viv wall.
Neither of these mats is achieving the temperature I want inside the viv. I can maybe get it to about 22.5C at best. I've tried placing a blanket ontop of the viv to block up the crazy amount of vents it has in the lid, but this doesn't seemed to of helped (and its probably some kind of fire hazard :/).
Currently using a thermostat for temperature regulation + fire safety reasons, but even without a thermostat (or with it on max) the mats didn't provide enough heat to get it to 25C

Can anyone offer any advice? I thought about heat cable and found some cheap, but when I asked the store their opinion they said they thought the cable wasn't suitable and to...yes you guessed it, try a heat mat. Right now I'm going round in circles with it.

The heat cables I were looking at come as follows:
4m 15w
5m 25w
7m 50w
9m 80w
and it looks like even the 4m one would be a little on the long side -I'm happy to put it all in there with use of my thermostat, or leave excess handing out it's not much of a problem to me.

The only other thing I can think of is getting a stand, ceramic holder + ceramic heat emitter and setting it up right above the cage, but I'm worried about melting the plastic. I can't open the hatch because they're such good climbers they'd probably be off exploring my room! Plus, it would be a costly option.

Thanks in advance <3

 

[Dave Jay]

An old method of heating herps was to silicone an aquarium heater into the lid of a bottle or jar filled with water. They're thermostatically controlled, adjustable and won't heat to a temperature high enough to burn when in water. If you hook it up to your thermostat even if it malfunctioned (very rare, I've kept multiple tanks since 1980 and it's only happened once with a heater more than 20 years old) you would still be safe. Other than that I think you've tried or considered everything I could think of.
One thing though, if a heat source is hot enough to melt the plastic the inside walls would be too hot anyway.

 

[SquishyPenguin]

An old method of heating herps was to silicone an aquarium heater into the lid of a bottle or jar filled with water. They're thermostatically controlled, adjustable and won't heat to a temperature high enough to burn when in water. If you hook it up to your thermostat even if it malfunctioned (very rare, I've kept multiple tanks since 1980 and it's only happened once with a heater more than 20 years old) you would still be safe. Other than that I think you've tried or considered everything I could think of.
One thing though, if a heat source is hot enough to melt the plastic the inside walls would be too hot anyway.

That's really interesting, I never would've thought of that! I don't have any spare heaters going atm but it's something I'll keep in mind.
Did you have any thoughts on the viability of the heat cable?
The only reason they seemed to not want to suggest it was because they were too long for such a small viv. The description says it can be placed inside around ornaments or on the outside, so I assume with my thermostat it wouldn't get anywhere near hot enough to burn them? If the only reason they're going to give me *not* to use it is because of the length I don't see why I shouldn't try it, theirs are on sale right now so they're crazy cheap.

 

[cold blood]

put the heat mat on an aquarium (side), put the roach enclosure inside the heated aquarium.