We were caught in the Texas winter storm/blackout earlier this year. We were in our Imagine 2970RL. With temps in the mid 20s, our 30,000BTU furnace was running at a 39% duty cycle at 62 degrees in the trailer. With temps in the single digits, the duty cycle became 79%. I kept calculations so I could estimate when to change out tanks. I didn't want run out in the middle of the night. Also keep an eye on your battery, below a certain level the furnace will not fire. With a cheap dealer provided lead acid battery, I had to charge it from the truck every couple of hours. Best of luck. Frank.