I'm trying to find a device that is used to warn when the temperature in the house is nearing freezing.
This alarm consists of a red light bulb screwed into a small metal box, apparently containing a thermostat that serves as a switch.
The box is plugged into an electrical outlet and placed in a front or street-side visible window.
(The unit is usually used in a home that is going to be vacant during the winter). If a passerby notices the light is on, they usually know to contact
someone responsible who can check the house to make certain the heating system is operating properly.

Googling finds nothing for me. I don't know what this device would be called.

vsharris

Did you find a home freeze warning system?

I found this on the internet, maybe it will work for you:

http://www.lumastrobe.com/lowtemp.html

Here's another one:

http://www.freez-warn.com

evergreen

the Honeywell Winter Watchman looks like the answer, model CW200A1032