This is for those that E-mailed me in the recent past about my Propex heater. I still havn't used it at altitude but it works great down to 0 degrees (as low as I've tried it.) The noise level doesn't bother me as much as the Suburban I had in 30 ft. RV yet it has it's own sound. My van is RB-Voyager top. Keeps the van cozy warm. RD