There is something wrong in either the combustion process or in the exhaust if you are experiencing extreme odors from your Wallas. Normally if the boat is positioned just right during the heator start up some unpleasant ordor can get back into the cabin, but that can occur with Kleen Heat also. Before diesel had a mandatory reduction in sulphur content that made a huge reduction in odor put off in the combustion process, we used the Kleen Heat. Since then, we have used #2 diesel exclusively with noticeable order only sometimes during start up or when the Wallas was not operating properly.
During our 2012 SE Alaska cruise the Wallas 95 quit during the first month, so replaced it with a Wallas 85 combo heater/cooker. In the next two months, 784 hours of burn time was recorded & confirmed by Scan Marine, when it was sent in for a over heating problem when back from the cruise. Over the years between the 95 & 85 models we have used these Wallas heaters for many thousands of hours both on Kleen Heat & different diesels fuels, so have experienced many different kinds of failures & operating conditions causing or not noticeable odors. Steve, with your stated overwhelming order occurring, then something is wrong in either the combustion or exhaust or possibly both. Yes, this can & should be corrected with Scan Marine your best source for solving the problem. This is their service number. 206-285-3675
Jay