I'm doing a very small controls job for a guy with waaaaay too much money. It will be a storage garage for his cars, 20 of them to be exact, all very high end. None of them are diesel. It is in an old industrial building with 45 ft. high ceilings. I'm good with the CO sensors, but am having issues with the NO2 sensors. As far as I know hot NO2 rises and cold NO2 falls, where do I put the NO2 sensors? If he does eventually produce NO2 will it be cold by the time it reaches the ceiling? What height should I mount the sensors? PLEASE HELP!