New with questions!

[Zombie-girl2009]

Hello everyone. I'm new to the forum and snake keeping, and recently rescued a ball python as my first snake. I have a few questions that I hope I can get answered. She is about 3 feet long and in a 36x12x18 wooden Viv with a radiant heat panel and a thermostat, but I'm having quite a bit of trouble keeping the temp up. The thermostat is set at 90 and the rhp stays on constantly because the temp never gets that high. Also, the humidity is currently sitting on 91% (I just misted the Viv. It doesn't stay that high.), but she is not shedding well. At all. I called the boy that gave her to me (he couldn't afford to feed her any more), and he said that in the four years he had her she NEVER shed in all one piece. Isn't that extremely bad?!? I thought they were supposed to shed all their skin in one big piece every time if they were healthy. She doesn't have mites, and as I said the humidity is high and never drops below 50%. I had a lady who owns a python breeding company where I live offer to trade me a corn snake for her. I really love her tho. I don't know what to do. :/ She eats pretty well. takes a medium f/t Medium rat every 14 days or so, but I'm starting to think that if I can't keep her healthy and comfortable as far as temperature and shedding go, that a corn snake might be a better choice because they aren't as picky when it comes to temp and humidity. Thanks for any advice and please go easy on me if I've made any mistakes. I did do a lot of research before I got her. She was originally in a 20 gallon long glass aquarium while I built the wooden Viv, and I covered most of the screen top during that time with plastic to keep the humidity and temperature up, but ever since I moved her into the new Viv, the radiant heat panel just isn't cutting it, and I can't put a light in it. Please help.