Thanks so far gang...
Just to further clarify...
There was a already a half day of full demand on the propane.
- hot water heater (always on)
- fridge on propane setting
- 3 burner stove and oven was used
- furnace trying to light
The switch over never turned red all weekend. It was turned toward the "in use " tank.
(New info)
Prior to the weekend I filled the spare "not in use" tank, hooked it up, but never turned it on. Maybe the lack of pressure on that side of the line mattered.
I also took off the "in use" tank to weigh it. (2/3 okay) Put it back on line, but (and I already knew better) I did not turn it on slowly. I did not think I tripped the OPD since water heater, fridge, stove worked fine.
Huh???