My Honewell RTH7400 somehow time-travelled a day into the future, and it turns out you have to “hack” it to fix the date on a hidden diagnostic menu. Full credit to Daniel from Bowerstudios.com for the solution.
- Select System
- Press and Hold Fan
- Should see 0120 with setting 20 blinking
- Press next to 0130, this is the year
- Press next to 0140, this is the month
- Press next to 0150, this is the day
- Press Done.
I’ve also grabbed the PDF instruction manual for the RTH7000-series in case you find it handy!