The enclosure I'm using (15 gallon glass terrarium) has a 10+ year old heat pad on it from a previous pet. It can't reach the temps I want with my substrate, failing to raise above 85 degrees Fahrenheit on top of the substrate. I've gotten a new UTH which is able to reach 90 degrees and I will be using it for the warm side.

I've left the old UTH on the other side for now, and I'm wondering if I should put it to use. It's colder where I'm living at, reaching the low 70's to high 60's on the cold side of the enclosure during the day, and the mid 60's during the night. Should I consider using the other, older UTH to heat up the cooler side? This would help raise the cool side to the recommended 75-80 degrees, but it could cause problems with the water dish in the enclosure, which could increase humidity.

Should I use this old heat mat to heat up the cool side, or should I leave it alone?

Thanks for any assistance. Sorry if It's brief, I wanted to keep things simple. Let me know if you want anymore info.