Anyone ever use a tank larger than 20# with buddy heater?

[Gordo]

Friend of mines RV furnace is on the fritz, so he bought a big buddy as backup, but normally has only 30 lb or a 100 lb tank with his RV. He said the directions for the heater said to not use anything bigger than a 20 lb tank. Not sure why, if it is a pressure thing? Myself, I would probably try the 30 without worrying too much, but thought I would ask.

[gasman707]

The pressure is the same in all tank sizes. That only changes with the air temp and the amount of gas consumption.  The bigger the tank the high the vaporization rate and the larger the appliances (BTU) you can use.  The issue would be safety. The bigger tanks tip over easier, which then could allow liquid propane to enter the hose and the heater. One gallon of liquid propane creates 270 gallons of burnable vapor.
My concern would be carbon monoxide poisoning hope he is not planning on sleeping in it.