Question:
The smoke detector in my trailer quit working, so I picked up a nice combination smoke and CO detector made by Kidde at a Lowe's. When I opened the package and started reading the instruction manual, one of the first things I noticed was, in bold letters, "NOT RECOMMENDED FOR USE IN RV'S/BOATS." I am a little upset by this because I forked out the extra cash for the smoke and CO detector and that they put this inside the sealed plastic package where you couldn't see it until after you purchased the detector. So I went to the KIDDE web site and found a question about whether they can be used in an RV in the FAQ's. KIDDE's official answer was simply that they are not designed for that purpose and they do not recommend it.

Does anyone know of a reason WHY a residential smoke/CO detector cannot be used in a RV? I am suspicious that there is no good reason other than the company covering its rear in case of some litigation.

Answer: -They probably don't want to go to the expense of having it certified to the NFPA 501 requirements for RV's in addition to the UL 217 certification required for household detectors.

-Propane sinks, because the propane molecule, C3H8, has a molecular weight of 44, substantially heavier than air. Therefore propane detectors must be installed near the floor.

CO has a molecular weight of 28, identical to that of N2 (28) and only slightly lighter than 02 (32), which are the primary elements of air. Since it has the same density as Nitrogen, it will not tend to sink or rise. In my camper, the CO detector is mounted near the ceiling.