How high should a CO alarm be placed to be effective? The manual implies, but does not explicitly say, on a wall no less than 4-in below the ceiling. Can it placed lower? Or, is it assumed the CO will rise to the ceiling like smoke and lower placement would be ineffective?
On the assumption that carbon monoxide is a problem when the furnace is on it seems reasonable to keep them close to the ceiling for earlier detection since warmed air will rise. However in a gas-heated forced-air home putting it on the wall above a vent would detect CO early as well–perhaps too early since the units can be very sensitive. I keep one in my furnace room as well (and I think against the manufacturer recommendation) but it’s never even gone off in there.