The vast majority of homeowners lack knowledge to be able to perform any type of work or maintenance on their propane gas systems. It is absolutely critical that propane gas systems which include all of the gas lines, fittings, and gas appliances be kept as gas tight as possible. These systems are very complicated and only persons having the requisite amount of knowledge and training such as a gas serviceman should be the only persons working on a gas system. I know that many appliances and specifically water heaters are marketed and major hardware stores such as a Wal-Mart or Office Depot as an appliance that can be installed by the homeowner. I urge you not to do this as it is extremely dangerous. History is replete with propane gas explosions that have occurred when the homeowner has decided to install an appliance, or perform any work on the gas system. Whenever a gas system has had maintenance performed upon it which requires the system to be shut down for any period of time a pressure test must be formed on that gas system before it is placed into service. Only a knowledgeable and qualified gas professional is capable of performing such a test.
Please do not perform any maintenance on your propane gas system or attempt to install a propane appliance. It is well worth the cost in safety to have a qualified professional perform said work.