Atwood RV Furnace will not start after changing propane cyl

Regarding that 6300.. I'd consider upgrading the "Electronics" part to a Progressive Dynamics 4600.. it's a Bolt in replacement for that part.

From time to time we speak of some very bad converters that can among other things damage your battery..... Not sure if the Parallex 6300 is. but Parallex bought out Magnatek and their 6300 was. and you did a fairly good job of describing the Magnatek 6300 (Unfiltered and battery circuits)

This likely has nothign to do with the furnace. but it will improve battery life.