HCA: Hermit Crab Association

Hello. I adopted 3 hermit crabs last year and have successfully kept them in a 20 gallon tank but I’d like to move them to my defunct 100 gallon fish tank but I’m not sure the best way to heat it. The small tank has a UTH attached to the back and wrapped for insulation. I’ve read a humidifier will be sufficient for both humidity and heat but I’m just not confident enough to make that decision. I want to get their new tank up and stable before moving them over.
Thanks for any help!!

Not sure who would say that a humidifier would help with heat? But a humidifier will only add humidity and moisture to the tank.
You can still successfully heat a large tank with UTH's. You might need more than one, which is fine, and you can insulate some brands as well. Or you might use heat tape (I have never used that, so can't offer specifics).

Thank you. I was afraid that information was incorrect. I appreciate the help.