How can I run my hot water heater while under way?

Hello C-Brats,

I want to upgrade my house batteries to lithium and install an inverter. Would it be possible to run the hot water heater while under way off the inverter? Do I need to convert the hot water heater to 12v? Just trying to get a game plan together. Presently I just run my generator to heat water but…

With how much amperage a hot water heater pulls, I think you'll be best to just stick with running your generator, if not plugged into shore power.

colbysmith said:

With how much amperage a hot water heater pulls, I think you'll be best to just stick with running your generator, if not plugged into shore power.

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That’s what the electrician said. I just hate running it when I’m around other boats.

There was a recent post of someone who had put a 12 volt element in a water heater, and ran it off the power from the engine--much slower heating. Another way is to do what we did on our last C Dory 25, that is to go the a smaller Bosch water heater, mounted uner the galley. That way there was far less water lost when running the cold water out before a shower, and we would heat the water to a higher temp,and then dilute it with a mixing valve just before the shower. With the Li 200 amph hour batteries and the 2000 watt Victron inverter we could run the water heater a shorter time on 120 V from the inverter. Also a black bag on the roof will heat the water rapidly in warm and sunny parts of the country.

I do use solar water bags on the roof that work great on sunny days. But that may not be often in the PNW…

How long are you underway? My water heater keeps the water fairly warm for most of the day. If you're just going from marina to marina with shore power at each place, it's usually fine for me. If you want to have warm water while at anchor or traveling for longer than a day, that's another matter.