You really need a thermostat dedicated to one heat source. Like a stat for your UTH and one for a CHE.. They heat in different ways and are made to put off heat in a different manner.. You can use one thermostat with 2 different heating element is your trying to get them both to work together, like 2 CHE's trying to traise the ambient air temps... Since you need the belly heat to be around 92 or so and you will need your ambients to be inthe 80's. Thats hard to do when you have one stat trying to do 2 jobs... Hope I didnt make it to awful confusing..lol..