what is an RHP?

maybe it helps when you make the insulation better, your numbers indicate that you constantly lose a lot of heat into the room. heating the whole room a bit would of course fix the problem, but its expensive.

i found out that RHP means radiant heat panel i dont see why you would want that. there is no reason to mix different products. you could just put more of the heat tape you are already using on top of the terrarium, and put a wood panel on top (or the next terrarium). same effect. except that you dont have this thick white thing in the enclosure. you could also increase the suface area of the heat tape, or install some on the sides. just put it on the outside and add some wood, so that the heat goes in. i like wood, but the plastic in the animal plastics stuff seems to be designed to handle just that. insulation around it will make the heating more effective.

basically just add more heat. could be on the top, on the sides, on the back, or more on the bottom. all on the outside. then add insulation, and you should be able to reach your goal and have it working just like it should, even when the room isnt that warm.

its based on the assumption that the bottom and the sides and the top of the animal plastics enclosure are of the same thickness and material. but thats the feeling i get when looking at pictures. if that is true, then you really have a lot of freedom.

im not sure if it can all run over the same thermostat (or t-stat channel), or if you need one for the bottom and one for the top or something like that. i think you need to put the different sections of heat tape on different channels, with their own heat probe.