Having cleaned and rebuilt those heaters a few times.as well as currently modifying my system for a fixed electric heat system to share the diesel heat ducting I have found a few items to watch out for.
Many of the boats have flexible ducts tywrapped close to or on the floor deck boards. As you route your ducts, try to select locations that hang from bulkheads, settee seat, and middle to top back of cabinets, you will thank yourself later when you use those cubby spaces and do not collapse ducts sitting on the floorboards. Do drop the duct to the floor level at the discharge vent locations.
Try to get your inlet air to your diesel heater from as high above the water as possible, and put a water trap/drain in the loop if you take air in from the cockpit lazarettes. you would be suprised how much Salt/saltwater can accumulate from condensing vapor drawn in at night.
Mount the heater with all of the mounting bolts accessible, and plan on extra hitemp fiberglass cover to protect the surrounding storage areas and ducts from damage. All the heat you save in the heater prevents additional cooling condensation, melting surrounding items, and less frequent cycling.
you will be amazed at how much salt can accumulate on the metal surfaces of the heaters.
Try not to put the heater above your head in the aft lazarette, the mounting will be much better and quieter with 3/16 floating rubber bushings holding the heater bracket to the storage locations. Wrapping the first 5 to 6 feet of ductwork with glass/felt seems to quiet it greatly.
I think you will find installing the heater with easy access , a great benefit. Due to the thing skin on the transom I do not recommend through bolting to any section of the transom, as some do. Seems to amplify the whole noise problem.
Enjoy and good luck.
I know you can get cheap deals on ebay for these used heaters, Are you planning on putting in a new heater or a rebuilt used one? I have an old Eberspracher DL5C that puts out plenty of heat but it is a power hog when it runs, the newer ESPAR (Glad they shortened the name) that I replacing it with uses almost the same power when on. The existing 80 watt load seems too much for my liking. A new ESPAR DL8 uses 115 watts when it is on. The airtronic 5 still uses about the same 80 to 85 watts when operating.
The Webasto AT 5500 on full uses about 90 watts, the TSL 17 is only 32 watts on full.........and the wallas 40 DT is even quieter, and uses less power in the size range a mere 45 watts on full, (12 watts on low). so those are much more battery friendly, than the ESPAR offerings. I had some other financial constraints when I purchased the ESPAR, I am not sure I would recommend them over the other lower power options. On our 35 Bene, we have the Webasto, and if you can get use to the turbine starting sound associated with that thing turning on, you can get used to anything.
