Calorifier/water heater location

[mbowser]

The new isotemp spa water heater showed up over the weekend and after some test fittings in various locations aft of the engine, I'm coming to the realization that I'm just too tall for boats (6'5"). Yes, I can mount the tank in several locations aft of the engine (or where the engine will be installed). However, if I do, it will effectively eliminate my ability to service the back of the engine or steering gear should I need to so I'm looking at alternate locations. I'd rather have a less efficient water heater than have a steering or engine failure that I can't fix because I can't access it. I should note that in the Niagara 35, the engine uses a v-drive and it is mounted backwards in the hull, with the belts at the aft end, so it's important that I can get to it. The closest logical location would be under the starboard settee which would require 2-3 meters of hose in each direction from engine.

So I guess the question is: Can the engine coolant pump (Westerbeke W27) handle moving the extra volume of coolant to and from the tank? Based on volume of cylinder calculations, a 5/8" ID hose would need an additional 12 ounces of coolant for every meter of run. So if the total length to and from engine were 6 meters, then I would need an additonal 72 ounces of coolant. Thoughts?