Most RV owners understand the basics of their coach propane system. This article will introduce some additional detail about how the propane system works, starting with some terminology. “LP” is an acronym for “Liquefied Petroleum”. Propane and Butane are the primary hydrocarbons in the Liquefied Petroleum family.

A frequently misused term is “tank”. By definition, propane tanks are those permanently mounted on an RV such as a motorhome. If the container is temporarily mounted such that it can be removed for filling, it is referred to as a cylinder (refer to figures 1 and 2). Therefore, the generic term is “container”,which applies to both tanks and cylinders.

Both propane and butane mixtures can be used in an RV, and LP dealers in North America may use either or a mixture of both. The differences are largely unimportant except when it comes to temperature. Butane has a vaporization temperature of approximately 32 degrees F, whereas propane is approximately -40 degrees F. Vaporization temperature is the temperature at which the liquid in the container turns to gas (vapor). This is important because RV appliances only use the vapor (with the possible exception of the LP generator). If it is too cold outside and you have a higher butane mixture in your container, the liquid may have a problem maintaining a high enough vaporization rate. If you have problems with your burners in cold weather, you should consider having your container refilled with an LP mixture containing a higher propane concentration.

Propane Safety

Modern propane tanks and cylinders have built-in safety devices that prevent containers from being overfilled, as well as excess flow valves that prevent gas flow if a high-pressure hose is damaged. Always ensure that cylinders are filled by weight and tanks are filled by volume. Make sure that the filling attendant always opens the vent valve on a cylinder or the liquid drain valve on a tank so the container is never overfilled. Even though there is an overfill protection device (OPD), it is possible for it to fail, in which case the vent/liquid drain valve will give a visual indication that the container is full.

It is important to have your RV propane system inspected annually. This should be performed only by a qualified RV dealership. The technician will check for and adjust to proper operating pressure and regulator function, ensure there are no leaks in the LP system, perform a thorough inspection of all gas appliances, and complete any required repairs. The proper operating pressure of an RV propane system is 11 inches of water, which is measured using a special low-pressure gauge called a manometer. The technician will also check to make sure the regulator properly locks up at a pressure of no more than 14 inches of water. In many jurisdictions, it is not legal for a licensed dealership to release an RV with propane system defects to an owner without the defects being fully and properly repaired. Therefore, be aware that if your RV is found to have problems with the LP system, you will likely not have a choice but to have the problem fixed. This may include replacing components or entire appliances, possibly resulting in a significant outlay of cash. Although the repair may be expensive, it ensures that your RV is safe to operate. Remember that propane is a very safe gas as long as it is maintained in good condition by a professional technician.

For an additional look into your RV propane system, be sure to watch this video from our friends at RV Repair Club.

About the Author: 

Steve Froese, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.