The day before I bring the water needed to fill the misters into the Cham room and it keeps it at a nice room temperature. They seem to like it and all approach the misting water when it sprays on them.
I don't warm my water but you could just put a small aquarium heater in your reservoir if you really want it warm. I figured that my room temperature water was fine and kind of helped with my temperature gradient.
What kind of water do you use for misting? Why i ask that is since i have not ever had a problem with keeping the water room temputure I was wondering if you could slightly warm it just not letting it come to a boil and making sure it cools to appropriate temp. I am just not sure if doing that will affect the water depending on the type you use(spring, distilled, treated tap ect.)