When I first bought my boat she was about 7 years old and had been rather neglected (and unused I suspect) for some time, so not surprisingly the central heating system along with most other systems didn't work properly and not at all reliably. It's an Eberspaecher diesel 5kw system that kept blowing fuses and glow plugs, amongst other failures. Being short of time and non to the wiser I had a boat yard "service" the unit. £300 later and all was well, albeit with summer approaching.
Then things started going wrong again, and again, and again with the same symptoms.
Eventually I stripped out the combustion chamber to de-coke it myself, job done I thought.
I noticed at the time too that somebody had fitted a fuel flow control valve before the metering pump, wrong ! this is now opened fully ideally it should be taken out.
With still getting blown glow plugs I eventually gave up & took the whole d@mn thing to a dealer in the Trafford area of Manchester who claimed that he could service it properly. (these units are based on truck cab heaters that are supposed to be serviced every year).
When I got it back 3 days later it looked like new, acid etched cleaned apparently, including essentially the fuel atomising area that the DIY guy can't get to !
So all for the Princely sum of £90 I now have a heating system that works superbly, didn't miss a beat right through the recent cold snap let's call it.
My advice to anybody suffering with one of these systems is to strip it out including control box which takes about an hour in my boat, or get it taken out and deliver it to such a dealer who can then clean it and test fire it to measure emmissions / correct combustion & deliver back as new...
Just wish I'd done this 3 years ago !