> Is there any reason why i would not use air from inside the boat to reheat instead of continually heating cold air?<
1. Moisture. The warmer the air the more water it can hold. The colder the air, the less water it can hold. The cold air you suck in from outside is dry. Dry is good. Recirculating warm moist air will recirculate moisture which will lead to
2. Condensation, that will cause:
3. Mildew, resulting from the moisture in the warm moist air.
4. Safety. A continuous supply of fresh (heated) air effectively pressurizes your boat purging of moisture (and CO, unless the furnace is the source of the CO).
5. The Captain. He always did things for a reason. Trust him. Your diesel furnace will have plenty of BTU’s to toast you out of the cabin even in below freezing conditions. Unless there is a really good reason my experience has been happiest doing things his way.
6. Re-sale. A non-Amel-standard installation will reduce your vessels desirability and re-sale value.
My 5 cents worth – hope it is helpful..
I am just getting ready to start installing a heater in Kimberlite.