Installing a programmable thermostat

My apartment has an antiquarian furnace, and I'm doing what I can to squeeze energy savings from it this winter. Earlier this month I replaced the furnace filter. My latest project was to install a programmable thermostat.

It's a simple way to eke out energy savings, particularly in northern climates. The idea is that you'll set the program to lower the temperature when you're asleep in your cozy bed at night, or out at work during the day. The savings at night are the more significant, and in an older house like mine, will probably equal about 1.8 percent for every degree celcius I drop the temperature.

So, if I drop from 20C to 16C at night, I should be looking at savings in the neighbourhood of just over 7 percent. The savings will vary depending on insulation and climate, and the scenario is different for people with heat pumps. But I expect a lot of renters are in my situation -- old, poorly insulated house with a big ol' gas or oil furnace. For more information, there's an interesting paper here by Andre Plourde, a professor at the University of Alberta.

A basic programmable thermostat costs about $30, though you can pay plenty more if you want something fancier. I bought mine when a $15 rebate coupon came with my Enbridge gas bill. So really, I'm out about 15 bucks for the thing, and should easily recoup the cost. And it looks a lot nicer than the old mercury thermostat.


How to install a programmable thermostat
This is surprisingly easy. Most older furnaces have a simple two-wire system and the wires are usually colour coded. Read the instructions that come with your new thermostat.

The first step is to slip off the cover plate of the old thermostat. It just slides off with a simple tug.

Notice the bubble of silvery liquid at the top. That's a glass tube filled with mercury. This is a hazardous material, so remove the thermostat with care and follow instructions from your municipality regarding proper disposal. In my city, one can bring them to a Community Environment Day or bring it to one of the city's hazardous waste depots.

After removing the cover, remove the screws holding the thermostat to the wall. These will probably be small flathead screws. Then unscrew the two wires from the terminal. Be careful not to let the tips of the wires touch. You may want to wrap them in electrical tape while you work.

Next, follow the instructions for mounting the new thermostat. On a two-wire system, each wire should be colour coded and easily screw into an appropriate terminal on the new thermostat. Then slide the face into place as per the manufacturer's instructions.

Programming the thermostat
My thermostat has four settings for weekdays and two for weekends. The idea is that you'll set it to lower the temperature when you go to bed, raise it just before you get up, drop it again when you go to work, and make the house toasty for your return home. On weekends, it's a simpler program to drop the temperature when you go to bed and raise it when you get up.

In my house, it's set for 16C overnight and 19C during the day, though I sometimes go up an extra degree first thing in the morning. I don't set it much lower during the day because I work from home (a simple two-program thermostat would have done me fine, but I couldn't find one).

Best of all, the new thermostat looks a lot nicer than the grotty old one. Being green is important, but aesthetics still count for something.