On the propane (Explosive gas) Detector.....
These come in two types.. .. So let's leave it for a moment and go outside and look at the gas tank. I will describe a class A motor home system. This is fairly common though two parts are optional.
You have the tank, and it's valve
Coming off that you may have a brass "T" like thing (Extend-a-stay) or not, this is an optional after market part.
Then comes the regulator, Normally it is what is sometimes called "White metal" though it's more gray/sliver in cloor, one or two disc shaped things, and there will be a removable, usually plastic, screw like thing on one of 'em in many cases.
And beyond that is another option.. an electric solenoid valve
IF YOU HAVE THIS VALVE, then the propene detector is your problem.. SOME models of propane detectors control this valve, You need one that does this,
The idea is if they go into alarm state, they SHUT OFF the valve.
NOTE valve can be on the tank side of the regualtor as well.
What does an electric propane solenoid valve look like?
Check out the owner's manual for your water heater, or just open the outer door on the water heater compartment and look, there is one there and it's obvious since it's just before the burner assembly, it has both pipes and wires going to it.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times