Plans change in life and when I installed the chiller system on my 53 about 8 years I was never planning on needing heat. Fast forward to now and hen I m about to move my boat to Watts Bar Lake in eastern TN on the TN river…. Heat needed in winter. converting the two chiller to reverse cycle isn’t worth it, and I m not even sure reverse cycle would be enough during the really cold weather spells anyway. I talked to Flagship Marine who built my chillers and AHs and they suggested either adding heating coils to the air handlers or using a water heater. The coils aren’t really an option since that would use way too much power out of the single 120-240/50 shore power. So it looks like the best option will be to add a 40 gallon electric water heater to the system which will bring the loop to the temperature needed to heat the boat. it s something I had thought about month ago when I first started thinking about moving the boat but dismissed as too easy. electrically i can easily power the WH by using a rotary switch in the ER to select chiller or WH without having to modify the electrical panel or run new wires. I like simple solutions
I explored this extensively when I bought my boat and moved it to Alaska. You are correct, reverse cycle won't do what you need and doesn't work well in colder water temps. I also found my AH's wouldn't handle the water temps necessary to really produce decent heat. I strongly recommend you consider adding a stand alone diesel fired system like a Webasto or others. These guys do a ton of these systems being in the NW - https://www.suremarineservice.com/Heat/ I went with a zoned system and it works really well. I even added an extra zone for my flybridge which gives me heat and defrost on my windows. Of course now I'm planning to move my boat to warm Mexico and will probably never use my heat system again
I don't think electric water heater is going to do it either, it's still going to use a ton of electricity no different than strip heaters. BTU's=BTU's. The strip heaters, you could close off certain staterooms and leave them off. I think you might want to really look into a diesel heater. At least for the salon level. That would be easy to do given the layout of your salon level.
The cold is not that bad in Tn so I don’t think a diesel system is warranted. The lows can dip in the high 20s for 2-3 days but then quickly get back up in the 30/40s in the afternoon. this is what flagship recommended so it s worth a try. Theee guys are pretty good.
What I'm getting at, is an electric water heater is going to use just as much electricity as a chiller on reverse cycle. BTU'[s=BTU's, Reverse cycle does work in that temperature. Water temp is what determines whether or not it works. I did the Great Loop one year in 2008, it was a 75' Hatteras, had reverse cycle package units mostly. We had ice on the bow 4 mornings straight it was so cold......20's at night, high less than 60F during the day. Boat was warm at night.
Problem with reverse cycle in my case is that I would need to remove the two chillers and bring them to the factory in Ft Pierce to add RC. The water heater(s) will actually use just about the same power as the chillers.
Not sure if you will be running the boat or not but a water heater with an engine water loop on either the generator or the mains would be a nice "booster" for extremely cold days.
I anticipate mostly short hops to anchorages then staying on the hook for a day or two so engine heat won’t help much
