Originally Posted by Coffee Break
See page 5 in the Installation and Operation of the Nautilus On Demand Water Heater (IW60) manual under Freeze Protection.
That's it. the freeze protection valve kicked in. the drain valve opened on its own when it reached 34F. as soon as i turned on water pump, it keeps flowing out the drain tube.
as soon as we got into warmer temp, the drain valve closed and is working properly again.
i guess i'll have to turn on the water heater prior to destination that is below freezing. otherwise it will refuse to work and give the error "clear fault and cycle power"
another thing that contributed to this problem - we turned off the furnace for the night. the inside temp in our coach got down to 34F when I woke up in the morning, it could've been even lower when we were asleep. in our previous trips, we always had the furnace on so we never ran into this issue.
how did we sleep in freezing inside temp? it was my wife's brilliant idea ...