I have just had an Eberspacher D4 fitted to my Bavaria 40. It is fitted in the lazarette, which does mean a lot of extra ducting to get the heat to the living areas. One issue I have had is getting enough outside air to the heater unit. The heater unit was cutting out after 10 mins due to overheating. I have had to have a larger air intake vent put below the seat at the aft end of the cockpit. There are already two slatted vents there, but not enough air was getting through.
There is a huge amount of heat loss in the ducting, particularly to the forecabin, so I’m rigging up a means of disconnecting the forecabin ducting at the saloon junction piece. Rick – you mention lagging. Do you know of suitable lagging material for the ducting? The ducting does get extremely hot and I’d rather be heating my saloon than the lockers, the hull, and hence the Firth Of Clyde.