Diesel Heater Exhaust Hose Connections
Kind of a long story so be patient.
We are living aboard in New Bern, NC and have experienced record cold weather for this area. We have (2) reverse cycle units but were counting on the Webasto diesel heater as the water temps dropped. We've tested the Webasto heater several times since purchasing the boat 2.5 years ago but since we were not living aboard at the time we never had to rely on it.
Just before the worst of the cold was predicted to hit I decided to make sure that it functioned okay. The unit started but produced copious amounts of smoke and after running and producing heat for a few minutes it shut off. Repeated process, same result the second time.
Ultimately traced the problem to a blockage in the exhaust hose that put back pressure on the unit. As I removed the hose to clear the blockage (appeared to be a chunk of carbon or soot) I found that the hose clamps were rusted and almost fell off in my hands. Turns out that when this unit was installed all Webasto had were steel clamps. These are not standard band clamps because the hose is corrugated SS to withstand the exhaust temps and you need higher compression to crush the hose against the fittings. The hose is covered with an insulating sock and the clamps are not normally visible.
Moral of the story - if you have a diesel heater check your hose clamps periodically. There was real potential for the exhaust hose to come off the fitting and allow CO into the boat. Hopefully the multiple CO alarms would have caught the problem before it became dangerous but CO is not something to take chances with.