Thanks for all the advice
, The reason I'm not crazy about installing a pressurized system is I have very limited tankage, only have 60L capacity (27' boat) and from what I've heard from all my friends who have pressurized systems is they do waste more water. This is also the reason I didn't install a tankless heater because there is more water wastage before hot water arrives, I also didn't want to deal with exhaust
involved with a propane
setup. I'm installing an Eccotemp undersink water heater ($217.00 Canadian). It's not a totally marine
unit but they do advertise they can be installed in RVs and boats and the unit is pretty compact. Talking with friends it made sense to install the 15L version because the water most likely would stay warm until the next morning. The idea of installing a ball valve seems like a pretty simple and inexpensive solution and I will do that for the time being. Installing check valves on both the hot and cold also makes sense. If it doesn't work
out then I will rethink the idea of going to a pressurized system. I'm in the middle of a galley rebuild
and am trying to fit in extra tankage for the water heater.
Thanks again for all the good advice!