"Feedback is also an issue, link pages are not reliable since they don't keep track with presses."

I believe page links would work if you create a pretty extensive flag system to keep track of where the system is at. Set a flag when you set the temp. and have the "HVAC" button on your homepage check to see what flag is set and have it link to that page. I've done this in a simpler form with lighting systems (on/off feedback) but this would definitely be more involved. Should work.