RV How To Guide: Chapter 1- Propane Systems

Propane systems are the most dangerous part of RVing.  It is very important to ensure your system is fully functional and passes all safety regulations.  In order to do this, we highly recommend you have your unit tested by a certified RV Technician, and gas certified.  This blog is for your information only.  We do not recommend trying to test your own propane system, and are not responsible for any outcomes.

The propane appliance system in a Recreational Vehicle has many elements. It is common to find a propane fridge, stove, furnace and hot water tank in most RV's. Each appliance will have a propane connection and some method of lighting each burner. For example, older RV's have propane furnaces that require you to manually light pilots to fire burners, while most newer furnaces have automatic ignitors triggered by a switch. As well, most newer fridges and hot water tanks have automatic ignitors. These appliances are relatively easy to fire. Most have a valve to turn, or a button or knob to push, and you either light with a match or activate ignitor. The stovetop is the easiest part; most work just like a gas barbecue and all ovens have a pilot light. Appliances have printed instructions of the operations step by step, located by the controls. The RV's propane system has propane bottles and a propane regulator to supply each appliance. Motor homes and van conversions have frame mounted propane tanks. The propane system is plumbed with copper tubing from each appliance to a steel main located underneath the RV's floor (see diagram). The main line is connected to the regulator and the regulator to the propane bottles. These are the basic elements of an RV's propane system.

Propane is directed to appliances from propane bottles. It first passes through hoses to a propane regulator. This regulates pressure to the propane lines. From there the propane is directed to a steel line usually found under the RV's frame. This enables all propane connections to be made outside the RV's body. In newer RV's there are no connections or tees inside the RV's body. All connections are potential leaks. Copper tubing is used from the main line to each appliance. Each end of the tubing is flared and connected with brass nuts. Finally the copper tubing connects to each individual appliance's gas control valve.

Many problems can arise with an RV's propane system, the most dangerous of all being propane leaks. These can be detected in two basic ways. Because most leaks occur at connections, you can check for leaks soaping each connection with a mixture of half dish soap and half water. Soap should be heavily applied with a paint brush and the propane supply must be on. If bubbling appears, this indicates a leak. Look carefully for continuous bubbling and make sure appliances are off. 

The second method requires a manometer. The manometer measures the pressure inside the propane lines. It will also tell if the pressure leaks off. Simply remove stove top cover and one of the burners- this will leave the gas supply tube gase. The manometers nipple then hooks onto burner tube, with the propane turned on at this time. The manometer will now read gas line pressure. This should be between 11 and 13 pounds per square inch. Now turn the burner off and ensure all appliances are off.  With another stove top burner turned on, bleed gas pressure to 5lbs per square inch. When 20 minutes elapse, look at manometer. It will read either higher than 5lbs or lower. If higher, the system does not leak and reads higher due to gas expansion within lines. If lower, the system probably leaks. Propane gas tests can be dangerous and should be done in a well ventilated area and away from spark or flame. In order to certify a propane system, you must be a licensed pipe fitter with recreational vehicle certification. Propane connection leaks can usually be fixed by tightening connections and testing with soap method. If all connections in a system have been soap tested and manometer leaks persist, there is probably a faulty gas valve at one of the appliances. A gas valve leak can be determined by capping off each appliance one at a time with a proper propane line cap. These are the most common methods of diagnosing and repairing propane leaks.

There are many reasons why a propane system cannot be certified.  Propane bottles must be re-valved every ten years.  Each bottle is clearly marked with a month and year (ie. 6-94).  Ten years from the date shown the bottles are out of date.  Mantle style gas lamps are now illegal in RV's, as are catalytic style heaters.  When gas valves leak through the pilot tube in the off position, they must be changed.  Leaking or broken regulators must be changed.  The hoses from bottles to regulator cannot be cracked.  There can be no tees or connections inside the RV's body, just direct connections to appliance gas valves.  Most importantly, the propane system must not have any propane leaks.

Recreational vehicle fridges are fairly complex.  Most work with propane or electricity and some have 12 volt battery power as well.  It is very important to completely level your RV before operating it's fridge.  These fridges have a cooling unit in the back filled with ammonia which, when heated, causes a cooling reaction.  Most fridges fail because of blockages in the cooling unit and if a strong ammonia smell is present inside the fridge, the cooling unit leaks and is probably beyond repair.  These cooling units can be rebuilt, but this is very expensive.  Inadequate heat at the cooling units base will cause poor fridge performance.  A burned out electric element or clogged up propane burner are common problems.  The RV fridge is definitely the most expensive RV appliance.

The RV hot water tank is fairly simple and straight forward.  Some newer models have automatic ignition but most have to be lit outside the unit.  It consists of a tank, either 6 or 10 gallon, a gas valve, a pressure relief valve, drain valve and a gas fired burner.  Some of the late model RV's have electric elements to heat water when the unit is plugged in.  The most common problems are: the pilot light won't stay lit, the pressure relief valve leaks or the pilot light won't shut off.  If the pilot won't stay lit, usually the thermocouple is faulty and installation of a universal thermocouple is inexpensive and easy.  Be sure to get the big end of the thermocouple right into the pilot flame.  The pressure relief valve has a rubber seal.  If it is leaking, sometimes tapping the release lever will reseat the seal.  If this doesn't work, the whole valve can be wound out with a pipe wrench and replaced.  Finally, if the gas valve has been turned to the off position and the pilot does not shut off, the gas valve leaks and must be replaced.

There are two basic kinds of RV furnace.  One is called a gravity furnace, basically because it is not fan driven and the heat dumps out.  The other is called a forced air furnace.  It has a fan to direct the heat.  All are thermostatically controlled.  Again, most of the newer models feature automatic ignition.  The models that have to be lit manually have the same problems as the hot water tank.  Another common problem that occurs after lighting the pilot, is that it blows out after the fan is engaged.  This is usually a faulty thermocouple or the pilot flame is not hitting the thermocouple properly.  The thermostat will engage the furnace fan.  A faulty thermostat can be checked by joining the two wires at the thermostat.  If the furnace fires, the thermostat is faulty.