Help me out, I may have been doing it wrong. On each trip with our travel trailer last year, I always went ahead and opened both LP tanks (I assumed they went to separate appliances, 1 to fridge/stove, the other to hot water heater and furnace). A friend recently advised that he always just opens 1 and leaves the other as a full reserve as both are plumbed to the same appliances. Which is correct, or does it matter?