small business owner

I’m working on an old Air Ease, Johnson Furnace Co. hanging space heater. The unit is using LP gas. The model # is KMS-65; The serial # is 1, the BTU input is rated at 65000, the output @ 52000 BTU’S. This is all the information available. I would like to know the operating pressure(inches of wtr. column) that is required at the gas valve pressure tap.

Thank you, Maury Burrows, Lake Mills Wisc.