Our main house runs on natural gas but we have a small outbuilding (my office) which did not have gas service and ran on propane. When we bought the place we did some upgrades to the outbuilding and told the contractor we wanted to convert to natural gas eventually so he should do plumbing and buy appliances with this in mind. This year we finally got around to the conversion and found it a very expensive proposition.
First, the plumbing requirements for natural gas and propane are completely different. It’s not just the different diameter connectors. Propane uses copper, which isn’t legal for natural gas. So if you do the conversion, expect to replumb your entire gas service.
In addition, don’t assume all gas appliances are convertible. We were able to convert our stove and heater with a kit, but the most expensive item, a Navian on-demand hot water heater, isn’t convertible. Now we are stuck with a $1700 bill for a new Navian and the old one goes on Craigslist.
To sum up, don’t expect your propane to natural gas conversion to be cheap or convenient. It will be many years, if ever, before we get back in lower utility bills what we’ve spent on this conversion. Best thing to do is decide what your permanent needs are when you do the original gas plumbing, then stick to it.
P.S. If you’re a regular reader, you may be wondering why I am telling you this in the otisregrets blog. I apologize for the diversion, but it’s in a good cause. Do a search for “propane to natural gas conversion” and there’s not much out there except this post. By sharing my experience, maybe we can save someone a buck or two.