How We Installed a Thermostat

Here at the Procure office, most of what we specialize in is pricing, product hunting, and the general theory of what makes your furnace tick. How’s a thermostat work? It measures temperatures and sends either digital signals or specific voltages over wires to make the system do your bidding. Yesterday, we got to actually trade some theory for practice. Specifically, I got to trade theory for practice. My home thermostat of 20+  years finally croaked.


My Symptoms

It was pretty hard to miss that the thermostat had died. As it began getting chilly outside and as the house started to feel more like a meat locker, we followed common sense and set the thermostat. At least, we tried to. On day 1, we pushed the little slider to ‘heat’, and the screen stayed dark. On day 2, we changed the batteries. The screen remained dark. Pressing the buttons really did nothing, but after some bored tinkering and prodding, the circulator pump came to life. Heat restored.

How much heat? We didn’t know. The home office was an inferno. Our cats refused to go anywhere near the baseboards they usually love to sprawl against. I put a fan in the window and even mother nature’s frosty 30ºF breeze couldn’t fight off the furnace’s heat. Our thermostat had developed a fever or it was nostalgic for the hot and lazy summer.


Other Symptoms of Failure

When your thermostat fails, you may experience some stranger symptoms. Perhaps the screen works and it acts as if all is well, but yet the furnace runs near constantly. Or perhaps the furnace never runs at all. It could be that it runs at the wrong times and never attains the correct temperature. What we’ve found is that any failure in just the right place will produce peculiar results. My home turning into an inferno when the thermostat’s never been set past 75º is surely proof of that.


What to Do?

There are two choices in these scenarios. Choice one is to call your HVAC Contractor. Choice two is to do some research and make the repair yourself. We’re going to walk through the steps I took to replace my thermostat.

  1. Exploratory Surgery
    I didn’t know what wires were actually involved in our configuration. I didn’t install this furnace or oversee it’s installation. At minimum, we needed two wires. At maximum, a thermostat can have near twenty wires in a household installation. I hoped to find at least three wires: Red, White, and “Common”.

    Red ☑, White ☑, Common… Not check.

  2. Research
    The lack of a common wire narrowed down what I could get away with quickly. In a perfect world, I would run straight to our suppliers and overnight a smart, wireless thermostat with more features than a 24 screen theater. These fancy toys are powered by a constant 24VDC from that common wire. Without that, I opted for a cheap, functional, battery operated, programmable Honeywell Thermostat. Honestly, anything that could be scheduled and kept the house comfortable was an upgrade.
  3. Install
    This really couldn’t have been much more straight forward. I removed the old thermostat, disconnected it’s two wires one at a time, moved them to the included Honeywell mount, attached the mount to the wall, installed the batteries on the new thermostat, pushed it to the mount, and proceeded to spend the next hour fine tuning when and how hot the house should be.
  4. Enjoy
    This is probably one of my favorite home upgrades. That might sound silly, but even that tiny grain of improved control over the house makes it a million times more comfortable and cuts down on heating costs. On top of that, I’ve got a nicer interface. Six multi-function buttons and a decent sized and resolution backlit LCD screen versus twelve buttons, three sliders, and a single line character display.

Should You Upgrade Too?

I’ll go out on a limb and say probably. If you’re thermostat is older, it’s worth looking into a nicer, modern replacement. I love that my new thermostat is easier to adjust, it’s more responsive, and it’ll run the furnace less often than the previous thermostat by lowering the temperature at night and during the day. These benefits are pretty hard to pass up.

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