or this...I was thinking water heaters but I could see propane heaters as well.
The building where the original fire started was the least completed one and I doubt there were any water heaters installed yet. Considering there were no windows in any of the structures, it seems illogical to even think there was any water service or gas service hooked up and 'active' anywhere in those buildings. Water lines would have frozen a few days back when it was 19 degrees.