JCP having some heat regulation issues

My 4 footer is in a 20 long tank with two hides, paper towel, and a water bowl (he is a new addition, hence the minimalist furnishings). Cool side is about 75 and the hot side is about 85. But he is always on the cool side! And when the temp drops below about 72, I turn on a night lamp for warmth, but he still stays on the cool side! Is he trying to cool himself for winter? He seems fairly active. Ate one mouse last week, and has now "returned" it. I will be feeding him again shortly, but I'm not sure how many medium mice I should offer, esp. since he is refusing to keep himself warm.

First question I have is how did he return the mouse - did it come out the way it was supposed to, or reverse gears and come back the way it went in? How are you heating the warm side (overhead or undertank heat)? and how are you measuring the temps. I keep my (JC/D)intergrades at similar temps - in fact, the cage heat gets unplugged once the temps go over 82 degrees in the spring/summer (easier than trying to regulate, since their cages are controlled by rheostat). All of them do very well in those conditions, and when faced with cooler temps - they will all eat at 75-78 (I do feed smaller meals during this period of cycling). Interestingly, my male will not eat if his "cool side" (or ambient, depending on time of year) goes above the low 80s. Keep an eye on your new addition, but I wouldn't worry too much at this point.

OK good, thank you. the mouse came out the back end, so all is good there. I was afraid he was cooling himself too much. How much should I expect him to slow down over the winter? I havent really got a good handle on how much he would like to eat yet anyway. I am using a UTH with a night bulb I turn on when it gets chilly. Do you have an estimate on how many mice he should be eating?

How much he (is it a male?) will slow down over the winter, will depend largely on sexual maturity and temperature. (sexually mature) Males frequently go off feed during breeding season...that is nothing to worry about. The species is fairly tolerant of low temps (diamond intergrades probably more so), as previously stated, so he may not be as affected by dropping temperatures as you might think based on previous experience with other boids. If you are not trying to cycle him for breeding, there are 2 main schools of thought regarding seasonal temp drops: 1) it is natural, and gives them a slow down period or "break", 2) why disrupt feeding and risk problems by dropping temps. That choice is yours. Personally, I do not cycle them except for breeding purposes...slightly lower temps over the winter, and maybe a reduction in feeding because of it, but nothing too extreme.
As for how many mice he will eat, I wouldn't push it too hard if the temps are on the low side. A few mice every week or two is fine. you may want to consider trying to switch to appropriate sized rats, though. These guys can get a bit prey specific, and not want to change over (my favorite intergrade did not willingly eat anything but gerbils for about 8 years). feeding 5-8 mice to an adult male gets old...not to mention expensive.

thanks again. I will offer I guess three mice for his next feeding. I think it is male. It was sold as a male, and my former xperience w/snakes includes corns only, so this warmer species is a little new for me. How often do you think he will shed? And when I run out of mice, prob when he starts to heat up, I will try to switch to rats, maybe earlier. We'll have to see how much he cools himself. I don't really feel the need to heat him up as long as he continues to stay on his cool side. I figure if he wants to get a little lazy and slow its OK with me. Might even help me to tame him down more, lol

I know I said that they are fairly tolerant of cooler temps, but that does not mean that you should not attempt to provide temperatures that are appropriate. (Translate that to mean: You bought him, you should "feel the need to heat him"). If you don't, there will likely be more consequence than his getting lazy and slow - he could get sick. Also, since you referenced your previous experience as being only with corn snakes - the cooling period that JCPs go through for breeding is not nearly as long, or as extreme, as that of corns.
As for how often he will shed - like corns, that will depend on how quickly he grows (related to temperature, and feeding)

I didnt mean to say I will not heat him. I understand he needs heat to digest and maintain his metabolism. I meant that I don't feel the need to raise the temp of his enclosure further. If he wants to slow down some, and hang on the cool side, I am inclined to let him do so. He will be maintained at the current temps unless he shows some signs that he is too cold. Are my current temps too cold? cool side, where he hangs mostly, is about 75.

The gradient you described in your first post will work well for him...so yes, the cool side temp of 75 is fine. I can't help but wonder why he stays there - is the spot over the UTH too hot? (lacking a temp gun, just put your hand on the spot...if you can't comfortably leave it there, it is too hot.) That would certainly not be unusual for commercial UTHs. It is all well and good to check air temps; but if the surface temp required to achieve them is too high, the snake won't go there.

Hmm.... hadn't considered that. I had problems b4 w/UTH's not working at all. Didn't consider it could be too hot. Will check into it.