We have just acquired the new A122 Rockwood. Too cold to camp in it yet, so we spent a night in it in the driveway. My SO went out to bed before I did. I'd turned on the Coolcat in heat mode. She came in a while later and complained it was just blowing cold air. I went out and checked, and she was right (of course). I checked online and learned that the heat exchangers like Coolcats lose the ability to provide heat when the temp is below about 46 degrees. Since it was 26 degrees at the time, it made sense. So, I kicked on the propane heater, which did a great job, but every time the heater kicked on, the fan noise took a few months off my life, waking me in a start from deep sleep. The Coolcat fan is also real powerful and noisy, especially right under the bed. Plenty of covers, so I just turned the thermostat down to like 50 degrees, and had a good sleep. I'm sure the standard heated mattress helped a lot, too!