Monday morning, when I walked from the bedroom end of the house to the other, I noticed that the temperature seemed unusually low. The house has two zones of hot water baseboard heat, sourced from a fuel oil boiler in the basement. I had walked into the other zone. I checked that thermostat, which had a simple LCD display and buttons for Up and Down. The screen was blank. I managed to take the front off, found the two AAA cells, and changed them. Still blank. It was dead.
Not tool long ago my electric utility had great prices on fancy new thermostats. I bought two. They were still in the unopened boxes. So I began the process of installing them. Step 1? Install the app! Which I did, followed by creating an account. Next step, have the app take me through the install. The base of the old unit was still on the wall, and the strip of connectors were well labelled; one red wire, one white W, and a little sticker that said C was not needed because the unit had batteries. So the app asked about the old wires, and I told it what I had, and the app raised a special message that it had to have a C wire, and sent me off to an explanation of what to do about it. Suggestions such as put an unused wire to use. Of course I had just two, nothing extra to put to work. The suggestions after that one were a lot more complicated - new wires from the burner control. No, not happening any time soon. (The reason the new thermostat needed the C was to power the WiFi. Of course.)
At that point I remembered I had bought another thermostat a year or two ago and never opened that one either. A brief search turned it up. No WiFi, just two AA cells. No need for a C wire. Based on the holes in the wall when I removed the base of the failed unit, I was putting up the third one in that spot, which of course meant two more holes. One found a stud, the other air and so that one got a plastic anchor. I finished the install and got the heat on in time to make my eleven AM doctor’s appointment.
That thermostat is programmable. Four time periods, seven days. I tackled that this afternoon. Reading the instructions that came with it, when I reached the part about programming, it referred me to the company’s web site for the complete owner’s manual. That pdf now resides in my Download folder. The process itself proved not to be too onerous, mostly because there is a Copy function to make the next day like one before it.
Remember when there was a glass capsule and the end of a bi-metalic spring, that made an electrical connection when tilted one way, and broke the connection when tilted the other way? Toxic stuff, to be sure, but no batteries, C wires, apps, or pdfs.
I’m sure the other thermostat I want to replace has no C wire either.
(Unrelated, but when I was getting a haircut today, mounted on the wall at the workstation was a gang of four duplex outlets. All but one was occupied. Six of the seven were wall warts. The seventh looked like one, but it was apparently something else, like a breaker, as the wire running out was not some skinny thing.)