Fun with Data

We've spent the last two days intermittently trying to figure out what's wrong with our new thermostats. Last night, we tentatively decided: it's us.

The old thermostats were mechanical: rotate a dial to the desired temperature. Since I like a chilly bedroom, each night we'd set it low, around 50 degrees. In the morning, we'd set it higher. With the new ones, we programmed it to do the same: drop down to 50 at 9PM, come up to 68 at 6AM. The heating part worked fine -- if the thermostat said it was 65 degrees in the morning, it'd kick on the heat. But the temperature never got down lower than about 64 degrees. Even if we manually set it to 50, and opened the window -- it's been around 35 degrees outside, last few days -- the room didn't get appreciably colder -- the minimum it'd reach was 62. I touched the heating elements once or twice, and they didn't feel hot, but I thought that perhaps I was just doing it between heating cycles.

And then it occurred to me.

With the old thermostat, I'd set it to 50 at night. I assumed that at that setting, why, that must be the temperature the room dropped to, overnight, particularly when it was cold outside (say, around 32 degrees), and even more so if we had the window open a tad. I never actually knew what the room temperature was, though, until the new thermostats, which have a temperature display, were installed. We wondered: could it be that the room never actually chilled as far as assumed? So we did an experiment. We turned the thermostat off, completely -- no heat at all -- opened the window (about 38 degrees outside), and closed the door to keep any stray heat out. We put a manual thermometer on the bureau. Two hours later, we went in, turned on the thermostat, and looked at the manual thermometer and the thermostat's display. Both said 63 degrees. Apparently, that's as cold as the room will get. Set it as low as you want, but that's it.

I'm guessing ambient heat -- from the lower floor, from other rooms -- is the reason, and we're not completely sure -- but it does seem reasonable.

Amazing what you can do with data, isn't it?