We have 2 20 propane tank and 2 12v g31 batteries. We get about 100 hours of run time out of the batteries with mid 20 nights an low 40 day. Setting the stat to 68. At night we have a cycle of 7 mins on and 6 mins off. Not sure about how it would do do in the single digits. I'm thinking it would be running full time and might not keep up with the stat.