Boat Heater Up and Running

I managed to finish the installation of the Red Dot boat heater yesterday, although it was a hot and long day for me that finished at 6 PM.

Heater tucked in between lower step supports

After taking some measurements I set off for the hose specialist with a note in Spanish stating that I I needed hosing to pass cooling water from the diesel engine to a boat heater.  I specified a length of 2.2 meters and gave him a hose connector for the diameter.  While he was selecting the hose I stated "por agua caliente" just to be sure that he chose something that resists temperature.  I walked out with a coil of "GATES 10LOC 5/8 INCH 300 PSI WP LOCK-ON" which is  fuel line for gasoline or diesel, as well as 4 clamps.

I then dropped by Seamar and purchased 3 meters of marine grade 10-gauge 3 core wire.  I could have gotten away with 12 gauge but I saw no harm (other than to the wallet) of trying to minimize electrical resistance.

Round silver pull switch at left of main switches

Back at the boat I began the task of physically mounting the heater, which is conceptually simple but made difficult in practice because of the tight space and very little tolerances.  Using the Dremmel tool I shaved off 3 mm off each side of the mounting bracket so that it would fit between the step supports.  Then came the painful process of bolting on the mounting brackets.  The lower pre-drilled holes on the bracket were OK, but I had to drill new uppers at about 2/3 of the way up to avoid a piece of timber framing running inside of the housing along the top of the bracket.  There were problems associated with drilling so close to side surfaces and fitting the bolts inside of a channel only 20 mm wide.

My biggest worry was fitting the hoses into the back of the unit.  The heater hose connection pipes had to pass through 1/2 inch of wood and if there was not enough pipe showing to enable me to put on the clamps then I'd lose several more hours enlarging the holes.  Fortunately the hoses fit nicely over the pipes, well inside of the wood surface, and there seemed to be enough room for the clamps. 

I removed the outlet and inlet plugs from the Volvo engine in order to fit the connectors and noted what appeared to be the remnants of a white thread sealant.  I telephoned Mark for advice and just as well, because not just any sealant will do, given the high temperatures and antifreeze coolant that it must deal with.  I then rummaged though my stores and found a tube of head gasket sealant that had been on board Pachuca when I purchased her.  The material inside seemed supple enough.  I phoned Mark again and after describing the color (a brownish black) and reading that it would not harden he said that it was worth a try.  I made the hose connections (outlet from engine to inlet of heater and vice versa) and opened the two engine coolant valves.

Return hose looping up from the left

After checking the oil level (spot on!) and opening the raw water and exhaust skin valves I started the engine, a container of coolant in hand.  My first concern was the level of engine coolant.  As it dropped because coolant was now filling the hoses and heater I added more, maintaining the proper level.  I figure that I had to add just over a half liter of coolant.  Once the coolant level had stabilized I used a lamp to meticulously inspect for leaks.  There were no leaks.  (YES!)  I then watch the engine temperature settle to a steady state 195-200 F and felt that the heater hoses were warm.  At that near boiling temperature I figured that the heater should be very effective while the engine is running.

Hose from yellow switch at right to heater, lower left

This success revived me and I decided to push on and complete the installation of the switch.  I took power from  the 15 amp  "cabin lights" breaker and for good measure fitted an in-line 15 amp fuse. I sited the switch away from the crowded electrical panel door in a location that made the mounting of the switch very easy.  After some tests to see what wire should go where I set up the switch and at the first stage of the pull I had low speed on the fan (pushing air the correct way), and at the second stage (fully out) I had high speed.  The wiring and crimping work were good the first time.  (YES AGAIN!)

I've been very lucky that this boat has offered me that one and only position in which to fit the heater.  It meets the criterion that the heater must be below the level of the engine's cooling system.  It has minimized the total hosing run to a miserly 1.2 meters and kept it out of the bilge, with likely immersion in cold bilge water.   It's out of the way.  It sucks in air pre-heated by the engine.