A good smart thermostat and hub should last you at least five to seven years. We want a setup that manages your energy bills and talks to your other gadgets without a struggle. Buying a bundle during Black Friday is usually the move because retailers want to clear out older stock to make room for the new flagship models.
Most of the time, last year's model does exactly what you need for a hundred dollars less. If you use the Discover it® Cash Back (Discover), you can spread that cost out while you wait for those energy savings to kick in.
The 15-month window is a firm deadline, not a gift. If you still have a balance when that time is up, the standard interest rate kicks in on whatever is left. Pay at least the $23.33 every month to make sure you finish on time.