Propane needs different orifices in the burners and gas valve to work. The holes are smaller. If you use propane merely for a test, You could reduce pressure slightly and try it. The propane has more pressure than natural gas. Usually before appliance, natural gas comes through meter at about 7 1/2 inches water column, where propane is 11 inches water column. Might work for a short time only to test. Be careful. I used to work on a lot of propane appliances, also keep in mind propane does not easily disperse in air as natural gas does. More possibilites for small explosion. If it is in a little dip or well in appliance, will sit there and not disperse easily.