The real estate listing states that the home we want has both electric and propane as energy sources...?

My husband and I have put an offer on a home that says it has both electric and propane. We looked at the house and the water heater and furnace are not propane. The only thing we could find that would be propane was a regulator coming from under the house to the back yard. What in this home could be propane? Any anwsers would help! :)