I had that with ours just after a knockdown. It turned out that there was a bit of water that had gone down the inner intake pipe (for the combustion air). Our installation has the exhaust on the side of the cockpit coaming. It goes initially upwards, then back on itself and downwards to below the level of the heater before performing a "U-turn" to go back up into the base of the heater unit. The water was stuck in the "U-bend" at the bottom of the pipe - just enough to stop air getting in. Unlikely perhaps but worth a look as the alternatives are expensive!
Not same system .... but similar prob. as other posts .... miniscule drop of water in tube stops my gas system working ... "pull of pipe" tap end to dislodge drop ... put back - all fine ...
I bought a Propex 2800 in Nov. After countless hours I still can't get it to work. It will work at home in the garage, it will work in Propex workshop, but not on the boat, that is using the same regulator pipe etc!
I have a meeting this PM with the suppliers engineer at the boat. Even if it works ( I believe it will work in milder temps, but not below, say 4 deg, yes it is on Propane) it will be coming off to be replaced by a Webasto.
Biggest waste of money I've ever had, should not be sold as suitable for marine use!
Hey guess what? Just got back from the marina, engineer turned up, nice bloke, bloody heater fired up first time!!!!!!!!!!!
Loverly warm air coming out the vents down below, got real nice and warm as we talked about the installation, as he sees it there is nothing wrong. He is as baffled as me.
Just a thought....whenever I've been away from the boat for a few days, gas shut off at the bottle, I have to turn on both the cooker and the gas fridge for around 30seconds to purge air from the system before the gas will light. The same occures on domestic mains gas if the main incoming tap has been off for some weeks.( No, there are no leaks on either which are detectable by normal pressure-drop tests). The Propex won't know this is necessary and will probably require quite a few starts before the gas gets to it, dependant on length/diameter of feed pipe.