Smart thermostat: what it won’t tell you when the power goes out
Updated
From Montréal, you open the app: the cottage living room is right where it should be, all good. Except the last reading is from last night, and the app only says so in small print. A smart thermostat is a good tool — as long as you know exactly what it can’t tell you.
What to check before you trust it
1. Look at the time of the last reading
In most apps, the temperature on screen is the last one received. Look for an “offline” label, an update time or a connection icon. A reassuring number that’s hours old tells you nothing about the house right now.
2. Find out whether it warns you when it drops off
Go into the notification settings. Some systems send an alert when the device loses its connection; others stay quiet and keep showing the last value. Test it yourself: unplug the cottage router for a few minutes during a stay and see what your phone gets.
3. Know what it does when power comes back
After an outage, a thermostat reboots. Depending on the model, it goes back to its setting, falls back to a default, or waits to reconnect to the network. The manufacturer’s manual will say. Try it while you’re there: switch off the thermostat’s breaker, switch it back on, and note the setting it shows.
4. Count the zones it can’t see
A smart thermostat measures the room it’s in. With electric baseboards, each room often has its own thermostat; if only one is connected, the other rooms are invisible. The basement, the crawl space and the cabinet under the north-wall sink never get measured.
5. List what depends on power and internet
Write it down: the thermostat, the router, the modem, the Wi-Fi extender, the leak sensor, the camera. In a Hydro-Québec outage they all go dark at once — which is exactly when the house starts cooling.
Why it goes quiet at the worst moment
An outage cuts the heat and the messenger together. When the power drops, baseboards stop, a propane furnace usually loses its igniter and blower, the heat pump shuts down. The router goes dark at the same time. The house cools, and the information that would have warned you can’t get out.
Rural internet is fragile. On the back roads of Dunham or the mountain roads of Sutton and Potton, the connection often runs through a single line or tower. A branch on the line, a provider’s equipment down: the cottage is offline even with power on.
Power coming back isn’t back to normal. A breaker can trip when service is restored, a baseboard might not restart, a propane appliance can stay in error. Meanwhile the thermostat may show a perfectly fine setting while the equipment it controls isn’t heating.
It can’t see water or snow. A pipe that froze during the outage and leaks at the thaw, a downspout torn off by ice, a buried exhaust vent: none of it shows up in a thermostat app.
Deciding: what it does well, and what it doesn’t replace
What a smart thermostat does well:
- Warming the place up before you arrive.
- Showing you a trend when everything’s working.
- Alerting you, if set up to, when its room gets cold or it loses connection.
- Keeping a history that helps you work out what happened after an outage.
What it doesn’t replace:
- Eyes on site when the power or internet is down.
- A reading from the coldest room.
- Spotting heating equipment that won’t start.
- Anything that isn’t a temperature: water, roof, snow, doors.
What belongs to a master electrician:
- Replacing or adding thermostats on line-voltage baseboards.
- Installing a generator with a proper transfer switch, or backup power for the router.
- Checking a heating circuit that keeps tripping.
One option people often look at: a stand-alone, battery-powered cellular temperature sensor that keeps reporting through an outage. It shrinks the blind spot without closing it: it only sees its own room, and cell service can also struggle in a big storm.
In an empty house, how long before anyone notices?
With a connected thermostat, you notice fast when everything works — and not at all when the outage is the cause. That’s when an empty cottage can cool for a long time with nobody aware. Hydro-Québec publishes grid status and current outages: if your area is hit and the cottage app is offline, assume the house is cooling.
How often someone stops by sets the maximum length of that blind spot. If your policy sets conditions for an unoccupied home, an app doesn’t necessarily replace the visits it requires: conditions vary from one insurer to the next, so ask your broker.
What we look at on a visit
Every visit, we read the main thermostat and compare it with the agreed setting, then read the stand-alone thermometer left in the coldest room. We check that the heating equipment is actually working: baseboards warm, furnace or heat pump starting. We look at the stove and microwave clocks — blinking means a recent outage — and through the panel door we note any tripped breaker, never resetting anything without your go-ahead.
If something’s off, we call you the same day with photos, and bring in a master electrician or another RBQ-licensed contractor if needed.