LPG/CO Detector

A mod AND a maintenance issue. It all started when the LPG/CO detector, right on cue, reached it’s “end of life”. Just a few months shy of its 5 year recommended replacement it started screaming for no reason. This is the Smart Alert 70-742-R. It sniffs for LPG and CO, and if it doesn’t see any it opens the solenoid on the propane tank shutoff (right after the manual shutoff valve) and allows LPG to flow. FIY there’s a 5A in line fuse dangling in most shore power compartments that provides power DIRECTLY from the battery to the system. This is where to look when there’s no power to it, and it is also a drain on your battery even with the battery switch OFF.

So it turns out the sensor is not made available by itself. You have to buy the whole kit, $300 and replace the solenoid. This was not what I had in mind, so i did the following. Some of you will scold me for this….oh well. So in the interest of full disclosure:


What I found for under $70 was an identical box, made by the same people, that is a “Two Wire” (The original is 4 wire). It is ONLY a detector and does not operate the solenoid on the shutoff. Model # 35-742-BL (for black). I then wired the solenoid directly to power, but through a switch.

The bad news: If it sniffs CO or LPG the system will not shut off the supply. But, if you’re in the coach you will hear the thing scream, turn of the switch and vacate the vehicle. Just like at home. The good news: The valve is now OFF at all times, unless I’m using the furnace or the Atwood for a Hollywood shower. (I have the electric water heater for day to day use, and now cook on an induction cook top). It’s the equivalent of going outside and turning the manual valve off when not using propane, which no one (that I know of) does. So that’s a good thing. Also, the next time the alarm craps out on me I will not lose my propane, although I WILL lose detection and must be aware of that. (Guaranteed to happen when it’s 15ºF outside in a Walmart parking lot.) Pros and cons…… The new sniffer in place.