I'm about to look for a programmable thermostat to replace a manual one. There are already a couple of good questions on thermostat replacement that make the task seem pretty straightforward for anyone who's done a bit of wiring (which I have done). The problem for me is this nagging doubt that, from a wiring perspective, all the thermostats I look at are not equivalent and only some would be able to work with the existing wiring.
So, my question is, as I'm looking for a replacement thermostat, is there anything I need to take into consideration? Do I need to read the back of the box for any specific statistic? Do I need to check the existing wiring first (number of wires, voltages, etc.)?
Best Answer
You have to check that the thermostat is compatible with your HVAC system. Heat pumps need the emergency heat switch, multi-stage high efficiency HVAC's have multiple fan settings, and electric baseboards may have 120/240v lines instead of the 24v wires. For the lower end models, or for those seen in the far north or south, you may have a thermostat for only heating or cooling, but not both.
So before buying a thermostat, check the type and features on your existing HVAC system and limit your selection to the thermostats that support your system. Then, see what features you want and how easy the system is to use. Some systems have wifi, some have programs for all 7 days instead of 5/2 split, but if you have all 7 days, how easy is it to change the setting for every day?