Thank you , Norma for all the great info and links. I bought my oven from craigslist from a guy in the country with a pizza shop. His whole kitchen ran off propane. This was a secondary oven he no longer used. I have it hooked up to a outdoor grill style propane tank and it works fine, but goes through the propane quickly and leaves an oder of non burned gas. It still works well, but my intuition tells me this is a natural gas oven. I will be hooking it up to a natural gas supply soon. I will check the orifices before doing so to see if I need to swith them over. Thank you again, Ron.