Are Eberspacher exhausts antisocial?

[lw395]

Yes, the 24mm one is Webo part # 92164A



No, it's only ever a few cc at worse, just into a cup or even soak onto a rag.

That would be for the small amount of condensate produced as a 'hot' exhaust cools after use. If you allow the exhaust gas to get cooled below 100degC, you will produce significant amounts of water, as in a condensing boiler.
More than one litre per litre of diesel burned IIRC.
Since these heaters are normally expected to use only a fraction of the fuel that goes into a vehicle, efficiency does not matter ever so much. But in heating a yacht, wasting so much heat may seem excessive? The latent heat of vaporisation is there for the taking as it were.
OTOH, you still get quite a lot of diesel for the price of an elaborate exhaust.