Discover more from Hatchomatic
Invasion of the Smart Thermostats
One of my favorite shows when I was kid was Beyond 2000, which I loved for a variety of reasons: the geekiness, the environmental hopefulness, the futuristic optimism, and let's not forget the Australian accents. I think it always left with me an idealistic vision of how technology could not only be used to improve lives, but also solve real problems.
I don't know if the show holds up, and if I'm being honest, I can't say I remember too many specifics from the show — it's been decades since I've seen it. I do recall one episode featuring an indoor ski slope in a Japanese mall — ok, hardly solving real world problems — but I know others definitely dealt with renewable energy and things of that sort. Ever since, I've wanted to try to bring some of that Beyond 2000 future into my actual life.
And that is how I ended up with 11 smart thermostats in a house for two people. 🤪
When the Nest Thermostat first hit the market a few years ago, I thought it was finally the dawn of the Beyond 2000 future. A thermostat that could sense if anyone was home and adjust settings accordingly? Where you could change its settings with your phone? Where it wasn't all dipswitches and inscrutable LED settings? Sign. Me. Up.
Shortly after it came out, I installed the Nest into the house we were living in at the time and it was pretty nifty — if not exactly transformative. I mean, it is just a thermostat after all. Nevertheless, I saw our energy bills drop and I enjoyed the throwback circular industrial design. Yet, as a Google product, it didn't perfectly integrate with my Apple-infested existence. So when we moved to our new house, which also lacked smart thermostats, I decided I'd use the Ecobee models, which feature HomeKit integration.
Since our property has three HVAC systems — one for the upstairs of the house, one for the main floor, and one for the garage — I ordered three Ecobees. The garage and main floor installations went fine, but I soon realized the upstairs system was a proprietary system from Daikin, which wouldn't support the Ecobee. So I returned the third and that was that.
But was it, really?
No, of course not. Because, while we had three HVAC systems, our house's original owner — an electrician named Doug — also installed a whole bunch of 240-volt electric baseboard heaters. There are a pair in the living room. One in the dining room. Another in the kitchen. One in the laundry room. The front hall. The downstairs half bath. And a pair in each in the three upstairs bedrooms. Furthermore, each room has its own thermostat. That's 9 baseboard heating systems and thermostats, if you've lost track.
Usually for 240-volt systems, you'd have a special thermostat that can handle that kind of voltage. But the former owner did something rather clever. For each unit, he inserted into the 240-volt circuit a relay switch connected to a four-wire thermostat wire, which itself was connected to an old Honeywell heat-only thermostat dial.
Wait, 240 whatnow?
To explain, imagine a circuit breaker with two wires coming out of it. Each wire is connected to the baseboard heater. This creates a complete circuit and allows electricity to flow, which heats the baseboard heater. Of course, a system like this would mean the heater would be on 100% of the time and we don't want that. You want a switch somewhere in that circuit so you can turn on and off the flow of electricity. That's what a thermostat does.
However, most thermostats can't handle being on a 240-volt circuit, which is the amount of power you'd use to run a dryer or central air conditioner. In fact, they can't be on 120-volt circuits, which is what regular outlets are, either. That's too much power. Most thermostats are designed to be on a 24-volt circuit. So what Doug did is he installed relays on those 240-volt circuits. When the relay is open, the circuit is broken and the heater is off. When the relay is closed, the energy can flow through the circuit and the heater is on.
So then the question becomes, how do you turn on or off the relay? The answer is through the thermostat. That's because the relay essentially has two sides. One side is connected to the 240-volt circuit as I just described. The other is a 24-volt circuit that connects to the thermostat. When the thermostat wants heat, it completes the circuit with the relay, which then closes the 240-volt circuit and the baseboard heats up. When the thermostat says the heat should shut off, it opens its 24-volt circuit with the relay, which then opens the 240-volt circuit and the heater is turned off.
With Great Power Comes Great Power Bills
Anyway, I figured I wouldn't be able to put a smart thermostat on these baseboard because of the way they were wired. So when winter came, I turned up the baseboard heaters and basked in the cozy warmth of radiant heat. The only disruption was when the electric bill came. At first I thought I was mistakenly being billed for leasing a Tesla; The bill was several times higher than the prior month!
Maybe the thermostats were simply turned too high. No problem, I'll just turn them down. Problem solved!
Then the next month's electric bill came and it was double the month prior! Bentley owners would have blushed!
Clearly it was time — past time — to take action. I took apart one of the old thermostats and came to realize just how antiquated it was. It operated using an old-fashioned piece of coiled metal. Essentially, when the metal was cold, it would contract and pull the circuit closed, thus telling the relay to deliver power to the heater. When the temperature had increased, the coil would expand, pushing the circuit open and telling the relay to shut down the heater.
Perhaps state of the art for 1963, these thermostats were not efficient nor particularly accurate, and certainly not very smart. So, it was time to replace them.
Ideally, I'd replace them with HomeKit-enabled options like the Ecobee. However, I wasn't sure that would work. For starters, I was still learning how this system was actually set up. But more than that, a key difference between the old-style thermostats and the new ones is that the old ones require no power. They work simply by the expansion and contraction of metal to open and close a circuit. Smart thermostats, on the other hand, need a constant source of power for them to work — you know, Illuminate the screen, connect to to Wi-Fi, share your personal information with Russian hackers, etc.
That constant source of power is delivered through a "C-Wire." But my setup didn't have a C-Wire. In fact, though the relays had only two wires coming out of them with which to attach to the thermostats. And that's really all they needed; after all, it was simply about opening and closing a circuit. However, luckily for me, Doug used four-wire thermostat cable to connect the relays to the thermostats. Because he didn't need all four wires, he just twisted them into two pairs.
This was lucky for me because in order to make the smart thermostats work, I needed at least three wires between the relay and the thermostat. So by untwisting the pairs, I could turn two wires into four and have (more than) enough to make this system work.
But I also needed something else. I needed new relays. The ones Doug used, notwithstanding their ties to the Eisenhower administration, weren't designed to send constant power to the thermostat. To fix this, I bought replacement relays for just this purpose. I also ordered nine Ecobees, opting for temporarily discounted basic refurbished models. Hey, I may be crazy, but I still have a limited budget! (Also, remember those crazy high energy bills? If my plan worked, these would pay for themselves in just a couple of months. 🙏)
Once everything arrived, I turned off power to the house and opened the electrical panel onto which the old relays were bolted. Digging through the wires, I removed and replaced one relay at a time, re-wiring each to the 240-volt circuit back just the way its predecessor had been. When my manly fingers proved too meaty to reach some of the wires, Cyn's fine digits proved just nimble enough to make the final connections.
Then I cut and stripped the thermostat wires and connected them to the appropriate relays — Red into R, Yellow in W and Black into C. (The green wires went, sadly, unused. Poor green.) Finally, with my handy label maker, I noted which circuit each relay was on for future reference.
On the thermostat side, I removed the old Honeywell dials and untwisted each pair of wires. Then I threaded on the Ecobee baseplates, drilled mounting holes, vacuumed the dust, inserted the wires into the relevant clips — Red into Rh, Yellow into W1, Black into C (sorry green) — and pushed the thermostats onto the baseplates. Although the Ecobee doesn't precisely match the profile of the Honeywells, they were close enough that any missing paint is hardly noticeable.
Then a quick trip to the basement to turn the power on and each thermostat came to life. (Well, almost. One didn't turn on, which was the result of a wiring mistake I was able to quickly fix. And another kept restarting, which turned out to be the result of a malfunctioning unit Ecobee replaced for me.)
I then spent some time with the Ecobee app on my phone and iPad to properly configure each unit. It's pretty great to quickly and easily configure not just their schedules, but to be able to give commands like, "Hey Siri, set thermostats to away" when Cyn and I are out of the house for the day. No need to heat a house when we're not there, after all. (Sorry pets, but you have fur coats. Suck it up.)
So, being surrounded by almost a dozen smart thermostats controllable from my phone and lowering my energy use, does it feel like I'm living Beyond 2000? Yeah, it really kind of does. And I'm almost looking forward to my next energy bill to see just how "smart" this whole endeavor has been.