I'm following this with interest. An excellent question.
But I do have a few concerns.
1. roll over valves have to be mounted above the filler. In many (not all) cases, it would be simpler at that point to vent outside the hull
. If it is lower it will seep, which is annoying but not serious with fresh water.
2. The tank is slam full. Auto tanks
have over pressure relief devises, but the water tank on your boat
does not. At the very least, when the hot water heater
comes on that volume will expand. Thus, you need to stop filling the tank before it is full.
3. Not all air releases allow air back into the system; many are one-way. The ag valve seems good, but the hydronic valve is probably one-way.
4. The relief needs to be MORE than the fastest you will ever draw water. Not a huge amount, but some of these valves are for pretty small flows and assume there is considerable pressure driving it.
None of these are show stoppers, just discussion points. This can work