You're singing my tune. We've been in this house for 24 years. I've always taken a propane lantern into the well house on these zero degree nights. Woke up with no water.
I can normally expect a one pound bottle to last 24 hours with the setting as low as it'll go. There was a mantle busted, so it didn't produce the heat needed, and spent the gas.
Must have quit gennin' just shortly before I went to check it because I was able to thaw the pressure switched with a cigarette lighter.
After 24 years, I bought a thermostatically controlled heater and installed it a few minutes ago.