I have a St. Croix corn furnace, hooked up to a LP furnace.
My theory was to set the furnace at 65, and Revolution at 72.

I'm still in the tweeking process of the settings but ...
When the LP furnace kicks in at 64, it shuts the Revolution down.
Vacume issue I think, while both have baffels.

Any thoughts / suggestions?

Hmmm. Don't know. I do have an SCF-050 hooked in parallel with my LP furnace, and am able to run them both at once. The SCF-050 can't quite keep up with the heat loss on nights when it's below zero, so I supplement with the propane in the mornings.

Do you get any error codes? If the propane furnace convection blower is maybe overpowering the blower on your Revolution, keeping air from circulating through there, then I could see how the corn furnace could overheat and shut down because of that. Do you think that's what is happening?

-- Dave