I bought a used furnace for my shop. It was advertised as "LP". When I went to look at it, it had no stickers indicating it had been converted to LP from NG. I ask the gentleman and he assured me it was LP. Well, being the skeptic/worryer I need to make my self perfectly sure. I took the manifold apart to check the orfice size. So now the question, this furnace has 4 burners, each has an orfice marked 55. It is an 88,000 btu input furnace. I checked some charts and I don't understand them. Sooo, has this furnace been converted to run on LP. I did not check the spring in the gas valve. Thank you for your educated experienced wisdom. gobble