Thank you for the replies. My sketch has many tabs so it's hard to post it other than a link to the web editor. I have attached it as a zip. Sorry to make those who are trying to help take that extra step.
It sounds like I have the heap and stack confused. It sounds to me like theres no way to "defragment" the dynamic memory on the fly.
I dont know what else to do. I've invested years in this project and it was working quite well at one point. Ever since I installed it in this house I've had this problem and at the time I hadn't made any changes. Its only since that I've made changes trying to track down this problem.
Thanks again for all the help. If anyone would be so kind as to take a look at the attached sketch and give me their feedback I would greatly appreciate it.
thermostat_mega_newest5_newProtoShld.zip (36.1 KB)