A smarter, but not the smartest, thermostat

by Gordon Meyer

One of the most popular projects in Smart Home Hacks, judging from my email, is Hack #41 Control Your Heat Remotely. It describes how to replace your existing HVAC thermostat with one that can be controlled via X10 either locally, or by calling in and issuing touch-tone commands. The latter approach is quite useful if you have a vacation home; you can turn on the heat (or air conditioning) from your cell phone before you arrive so it's nice and cozy when you get there.

About two months ago, when I realized that the thermostat in my home needed to be replaced, I was tempted to buy one of the thermostats that's used in that hack. It's seemingly right up my alley, but I decided to take a different approach. I went with a modern, but non-automatable thermostat. I know, I was surprised by my decision too.

I hope they don't throw me out of the Home Automation Geek Society for this, but here's the deal. An automated thermostat wasn't right for me. Here's why:

My scheduling needs are simple. Somebody is usually at home (both my wife and work at home) so changing the temperature to an "unoccupied" setting doesn't happen too often. Too bad, that's a great way to save money and easily handled by a home automation system, but I don't need that capability.

My home automation setup is volatile. I frequently try out new devices and home automation software so my system is in a lot of flux, and sometimes not working at all. I was nervous about maintaining reliable HVAC control in this kind of environment and didn't want to put my system's S.A.F. rating at risk. (That's Spousal Approval Factor; a key element for success.)

I didn't have time. While the winter thus far in Chicago has been mild (at least for Chicago), it has revealed a bad flaw in our home's HVAC system. And I needed a replacement that I could install quickly. We're at home a lot, remember, and cold fingers makes for slow typing.

What was wrong with our old thermostat, you ask? It actually worked fine but was installed in a horribly inefficient location. It took me months to figure this out, but I think there were a couple of factors that hid the problem.

We moved in last Spring, and a lack of cooling is much harder to identify than a lack of proper heating. When our air conditioning ran constantly we were willing to chalk it up to those infamous hot-n-humid midwestern summers. Also, since we live in what used to be an old factory, we expected some air circulation issues. So, we assumed, that while we might have an underpowered air conditioner, it was more likely just the way things were.

But two things happened in the intervening months that caused me to suspect that there was something wrong. First, the weather got cold and our discomfort was more frequent, and more importantly, we renovated our kitchen and added an eat-in dining area. This meant we were spending significantly more time in that part of the house. And whenever we had the kitchen lights on, it got cold.

The kitchen? The lights on?! What in the world? Well, it turns out that the thermostat is mounted directly above the dimmer switch for the kitchen lights. Dimmers work by constricting the flow of current to the lights and the excess energy is released as heat. Which is a problem when the thermostat is just an inch above the switch. The heat from the dimmer rises and makes the thermostat think the room is 10 or 12 degree warmer than it really is. Yikes!
thermo_80.jpg

Here's a picture of the old thermostat. If you put your fingers on the wall just above the switch you could actually feel the heat. If you look closely, you'll see the thermostat reads 80 degrees Fahrenheit. Actual room temperature at the time was 68F.

So, to jump to the happy ending, I decided to replace the old-school thermostat with a Totaline Wireless Thermostat System. The primary reason for selecting this model is that the wall-mounted portion is only a signal transceiver, the thermometer is in a battery-powered remote control that you can move from room to room. Now the hot wall doesn't interfere at all, and we've gained the advantage of taking the remote unit with us as we move about the house. This means that the HVAC system is responding to the temperature of the room where we are, not some fixed point in the house. A very nice solution for open-loft living. It's especially nice at night when the temperature in the bedroom is the only area we care about. Also nice is the ability to turn up the heat a bit just after waking up, and before leaving the comfort of bed.

Installing the new system was easy, it was a wire-for-wire replacement with my old unit. (The only stumbling block was the funky wiring terminals; if you get one of these remember that you connect the wires to the side of the terminals, not the tops.) I sometimes wish that the remote unit were more fashionably designed, it's a square box about the size of a dish sponge, but on the other hand it is easy to find when you want to adjust the settings.

So, I'm a happy (and warmer) camper, and it's not a very fancy solution, so perhaps there is a lesson for me in all this. However, that won't stop me from coveting this thermostat, with a built-in web server, I just can't help myself. Maybe next time.