The 15-minute project that took a week

It should have been easy. Two screws and five color-coded wires. At least, that’s what I thought on Monday when I decided, just before breakfast, to upgrade the old thermostat for one of those new fancy “smart” devices. You know, the kind of gizmo that displays a beautiful HD screen, which, of course, you don’t even need because it also has an app from the app store.

A week later, after myriad calls and emails to tech support to Ecobee (the manufacturer of said smart thermostat), after conversations with the power company, after scouring and deciphering blueprints for electrical wiring for the house, after scrolling through endless YouTube DIY videos on HVAC system problems, after several trips to the hardware store, and, after crawling through an attic full of insulation and dust to perform surgery on the heating system, I could yell: “Mission Accomplished.”

The new, fancy, “smart” thermostat

To be fair, it’s kind of my fault. OK, it is my fault.

As every manual for any device that requires electricity will state up front in extra bold letters: “TURN OFF POWER BEFORE PROCEEDING.” Or something to that effect.

But me, hey, I’m an experienced DIYer. I know how to work with hot wiring. And I also knew this was 24-volt direct current with very low amperage (I would learn the exact amperage by the end of the week). So all I had to do was be careful not to let the wires touch or ground out in any way.

The old Honeywell box came out, no problem. The sleek Ecobee went in without a hitch.

The only downside was that the new one wouldn’t boot up. After calls to the company that makes the thermostat, they had me perform a quick test and determined that there was no electricity coming in to it.

Calls to the power company came next. More tests. Still no power. I even reinstalled the old Honeywell and, sure enough, no power.

The mystery unfolds

That’s when I pulled out the blueprints. We just purchased this house a few months ago. The home is only 18 years old, so I knew it was properly wired for the thermostat. I was hoping to find some sort of a breaker switch and I did. But it was a wild goose chase.

The Youtube videos made it clear: The breaker switch for the HVAC system must be inside or near the furnace, which is in the attic.

But this required a ladder, which we had not yet purchased. (Sidenote: curbside pickup at Lowes and Home Depot is a wonderful thing. )

So, new ladder in our possession, into the attic I went. Only one problem: it was the wrong attic. I figured the furnace would be near the air intake, which was just outside the garage. But the garage crawl space yielded no such thing.

The other entry point is in the laundry room. So we dragged the ladder into the house and up I went, again.

Sure enough, the furnace was on this side of the house. All that was required to reach it was to crawl on hands and knees through loose insulation, but at this point, I was not giving up.

There was a power switch to the heating system. I reset this and could hear the transformer buzzing inside. That was a good sign. But, Sherry, aka Ground Control , reported no life in the thermostat yet.

I turned the switch off and opened up the panel, as instructed to do on all the YouTube videos. I tried a couple things, but Ground Control continued to report negative results.

Then I found a schematic on the inside panel. It showed a fuse between the transformer and the motherboard to the heating unit.

I located the fuse and pulled it out. Sure enough, the rascal was blown.

The fuse is a little 5-amp doohickey intended for automotive use.

“Why on earth would an entire HVAC system for a 2,600-square-foot home be dependent on this little itty bitty device with a sliver of wire to keep it running?” I rhetorically asked my trusty partner.

“Single point of failure,” Sherry responded, as any engineer would. (Weakest link in the chain is what we mortals say.)

What I did not ask out loud was: “Why on earth did I not shut down the entire power grid before installing the thermostat in the first place, thereby avoiding blowing the fuse?”

The culprit.

Closing in

But this was no time for self reflection. In fact, it was 5 p.m. on a Saturday and we were burning daylight. We began scouring web sites to see who might carry this esoteric, antiquated contraption. Neither Lowes nor Home Depot in our town had one in stock. We could wait a week, though.

But we weren’t waiting another hour.

We found the thing in stock in the next town over, a mere 15-mile drive.

So off we went.

An hour or so later, home again, I ascended one last time into the attic, I installed the new fuse. Still no thermostat blinking.

At this point, I was at wit’s end. I picked up the panel to reinstall it to the furnace, and that’s when I discovered a safety switch that automatically shuts off when you remove this panel.

I pressed the switch in and asked, one last time for a report from Ground Control. I was hoping to hear “All systems are go.” Instead, what I heard back was shorter and sweeter:


2 Replies to “The 15-minute project that took a week”

  1. When working on wiring, always remember… there are land mines and tripwires everywhere. I’ve learned through experience to 1: shut down the breaker for the circuit in question (the hard way) and 2: the main breaker if you’re in the main panel. Luckily I learned lesson 1 before attempting the next level.


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