How-to
Thermostats and freeze alerts
A smart thermostat with freeze alerts warns you when the house gets cold: cheap insurance against frozen pipes at a cottage or while you are away.
Used for: Frozen pipes
Our picks
Deep cold snaps / Extreme heat / Mains (plug-in)
ecobee Smart Thermostat Enhanced
Deep cold snaps / Extreme heat / Mains (plug-in)
Google Nest Thermostat
Freeze protection
ecobee Smart Thermostat Enhanced:
Phone alert when the house gets too cold
Google Nest Thermostat:
Winner
Turns the heat on, even in Off, and notifies
C wire Tie
ecobee Smart Thermostat Enhanced:
Power Extender Kit in the box
Google Nest Thermostat:
Usually works without one
Systems Tie
ecobee Smart Thermostat Enhanced:
Most 24 VAC systems, heat pumps with aux
Google Nest Thermostat:
Most 24 V systems, boilers, heat pumps
Warranty
ecobee Smart Thermostat Enhanced:
Winner
3 years (5 if fitted by a pro)
Google Nest Thermostat:
1 year
In an outage Tie
ecobee Smart Thermostat Enhanced:
Alerts need Wi-Fi and internet
Google Nest Thermostat:
Alerts need Wi-Fi and internet
Overall winner: ecobee Smart Thermostat Enhanced, 8.5 vs 7.8 on our score.
Choose the ecobee Smart Thermostat Enhanced if you want low-temperature alerts and a longer warranty
Choose the Google Nest Thermostat if you want the heat to come on by itself in a cold snap, on a smaller budget
US retailers
Before you buy
- Check the wiring Most smart thermostats need a C-wire for steady power; check your system before you buy.
- Confirm the alert Make sure low-temperature alerts are a feature of the model and app, and set the threshold yourself.
- Plan for outages No power or internet means no alert. A battery sensor on a hub with backup fills the gap.
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Guides
Freeze alert questions
Will a smart thermostat stop my pipes freezing?
It helps if the heating still works. Google’s Safety Temperature turns the heat on even when the Nest is set to Off and notifies your phone; the ecobee sends a low-temperature alert. Neither can heat the house if the furnace or the power fails.
Do freeze alerts work in a power cut?
Usually not. A thermostat’s alert travels over Wi-Fi and the internet, which go down with the power. A battery leak and freeze sensor, such as our water alarms, on a hub with battery backup covers the gap.
Will a smart thermostat work with baseboard heaters?
Not these two. Both are made for 24 V systems such as furnaces, boilers and heat pumps, and ecobee says its model doesn’t run line-voltage baseboards. Electric baseboards need a line-voltage thermostat instead, so check your heating before you buy.