Yes, you can use propane, but you need to get a different sized orifice for the burner alowing, I believe, less gas coming in. , maybe from rinnai, maybe from a heating ventilattion and air conditioning specailist, maybe from your propane dealer. My propane dealer says that I am suuppose to contact them to come out every time I hook something up to the existing line to make sure things are kosher.

If it can be converted to propane then yes if not no way