Last week I installed a D4 in a 25' Bayliner. Straight forward location to port as you step down into the wheelhouse and ducted to just one vent. We used a 3 gallon boat can to supply it from the fish box.
Biggest pain in the rear ever is Espar wiring; the controller & fuel pump need to be wired from scratch and you basically "build" the connector with small components that are really a PITA.
I strongly recommended to the gentleman that if he ever buys another boat and heater to go with the ease of the Planar.

Sent from my iPad using Tapatalk