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*Please note: the propane regulators in the video above and photos below are turned to face away from the trailer for display purposes only. They should face toward the trailer when towing to protect from damage.*
Propane is an essential fuel source for RVs. It is used to operate appliances like your water heater, furnace, refrigerator, oven, and cooktop, and it’s especially vital when you’re boondocking without electrical hookups.
Because it’s a flammable liquid, you need to know how to connect propane and safely turn it on, and that’s true whether you’re renting an RV or you own a new motorhome. So let’s cover the basics of RV LP systems and how to use them.
The Different LP Containers and Their Locations
There are two types of LP containers: DOT cylinders and ASME tanks. DOT cylinders are the removable type on most travel trailers and fifth wheels. ASME tanks are the type that are permanently mounted to the frame or floor of motorhomes and accessed through an exterior compartment door.
- DOT = Department of Transportation
- ASME = American Society of Mechanical Engineers
On travel trailers, you’ll typically find DOT cylinders mounted to the trailer’s tongue or, in rarer cases, to the rear bumper. On fifth wheels, the cylinders will usually be found inside a storage compartment.
Towable RVs may have one or two cylinders, with both being found in the same location on travel trailers but sometimes being located on opposite sides of a fifth wheel.
Remember that a propane cylinder cover protects cylinders from road debris on travel trailers. If you have two cylinders, you’ll also have a changeover regulator (automatic or manual) that allows you to pull from one tank at a time.
Throughout the rest of this article, here’s your reference guide to the language we’ll use when referring to the different types of propane tanks:
- Tanks = ASME tanks found on motorhomes.
- Cylinders = DOT cylinders found on towable RVs.
- Containers = the generic term referring to both.
Do I Need to Refill or Swap Out My Propane Containers?
Most propane fill stations will top off tanks or cylinders at your request. The exception might be if the station’s location makes it impossible for you to pull your motorhome close enough for an attendant to refill your tank.
Cylinders can be swapped out or refilled. This provides more flexibility for towable RV owners. But tanks require an LP refill station to top off propane, which can be more logistically challenging for motorhome owners.
Propane Safety Tip: If, at any point, you hear a hissing sound or smell a strong scent of propane, STOP. Close the valve on the LP container and inspect the fittings and connections. If the problem persists, close container valves and contact an RV service professional. NEVER search for a propane leak with an open flame.
How to Connect DOT Propane Cylinders
For those dealing with propane cylinders, here’s your step-by-step process:
- Turn off all LP gas appliances inside your RV. This includes your stovetop, oven, water heater, furnace, refrigerator, and generator.
- Remove the shroud covering your LP containers.
- Flip the switch on the changeover regulator to the container you are not removing (for two container setups). The switch should be set to a straight vertical position when swapping both containers (or for single-container setups).
- Close the valve on top of the LP container you’re swapping out.
- Unscrew the security bar holding the containers in place.
- Unscrew the pigtail from the container(s) you’re swapping out.
- Remove the empty container and set it aside.
- Place the full container in its place.
- Remove any plastic cap covering the LP gas outlet.
- Screw the pigtail onto the new container.
Tech Tip: The green plastic knob on the end of your pigtails should only be tightened by hand. No tools should be used to attach pigtails to LP containers.
How to Safely Turn Propane On with DOT Propane Cylinders
Now that your filled cylinder is connected, here’s how to safely turn on propane for your towable RV:
- Set your changeover regulator switch to point toward the container you want to use.
- Open the valve on top of that LP container. Open it partially to allow the system to pressurize, and then open it fully. In a two-container setup, the reserve container valve can be opened if your changeover regulator is automatic.
- Check the LP level indicator on the regulator. It should be clear but will change to red when your first LP container is empty, and it’s time to switch to your second.
- Go inside your RV and open at least one window and/or roof vent.
- Test the most upstream propane appliance first (the appliance closest to your LP cylinders). Your cooktop is usually your best option (if applicable).
When you run out of propane, turn off all appliances and reverse this process to swap out an old tank and swap in a new one.
Propane Safety Tip: Valves on all LP cylinders should be completely closed before towing.
How to Refill ASME Propane Tanks
Propane tanks should only be refilled at designated locations by an attendant that has been trained to do so safely. In preparation for refilling ASME propane tanks, you should:
- Park close enough for the attendant to reach your propane access compartment.
- Shut off your engine.
- Turn off all propane appliances, including your stovetop, oven, water heater, furnace, refrigerator, and generator.
- Instruct all passengers to exit your RV and wait safely at a minimum distance of 25 feet from your coach.
- Follow any additional instructions outlined at the refill station.
NEVER smoke or operate any ignition source while propane is being filled. The National Fire Protection Agency (NFPA) mandates that propane dispensing equipment must be at least 25 feet from open flames and sparks and 10 feet from combustible materials.
How to Safety Turn Propane On with ASME Propane Tanks
Wait until the attendant finishes filling your tank and returns all dispensing equipment to its storage location. Then you can proceed with these steps to ensure safe propane operation inside your motorhome.
- Check that the attendant opened the service valve on your tank (accessed through the exterior compartment door).
- Go inside your RV and open at least one window and/or roof vent.
- Test the most upstream propane appliance first (the appliance closest to your LP tank). Your cooktop is usually your best option (if applicable).
Propane Safety Tip: Motorhomes are designed for the safe operation of refrigerators using propane while traveling. No other propane appliances should be operated while driving.
Additional Propane Safety and Usage Tips
Follow these tips to ensure the safe, efficient operation of your RV’s LP system:
- Check your propane cylinder alignment. On travel trailers with cylinders mounted on the tongue, the changeover regulator and service valve opening should face the unit. While your tank cover provides protection, this is also vital for preventing damage from debris flying up while towing.
- Never fill containers past 80% capacity. Propane expands in hot temperatures, and the pressure inside LP containers increases. Filling past the 80% threshold creates a significant safety risk when camping in hot climates.
- Keep containers at least ½ full when winter camping. Propane boils at -44℉, but boiling occurs more slowly in cold temperatures, reducing the vaporization rate to downstream appliances. Keeping your containers at or above 50% capacity increases the wetted surface area inside the tank and increases the vaporization rate to keep your appliances operational when RVing in the winter.
- Maintain your propane leak detector. Regularly check the batteries in your propane leak detector and replace them if needed. Follow the manufacturer’s instructions to test for functional operation at recommended intervals.
Propane safety cannot be taken lightly, regardless of the type of RV you own or rent. As extracted, propane is colorless and odorless, but a substance known as ethyl mercaptan is added to give it that rotten egg smell.
When in doubt, and that smell is present, shut off all gas appliances and get out until you locate a knowledgeable RV service technician to troubleshoot your propane system.
Do you have any additional questions or comments about connecting, refilling, or turning on propane for your motorhome or towable RV? Let us know in the comments below!
Why do you recommend opening a window or roof vent when propane is heavier than air? For safety you should open a door!
I did not see you doing a leak test with a wet solution?
It says that the valve assembly should be facing toward the trailer. The one you were working on was facing forward and the one in the example with the girls was also facing forward??
That was some good things for a new person to know.
Thanks = Don
Hi Robert! You are absolutely correct that propane is heavier than air and will settle to the bottom of a space in a perfectly still environment. However, your RV will rarely be a perfectly still environment, especially with a window, roof vent, or door open. In real-world conditions, propane will mix with air and won’t separate. But, to your point, more ventilation is better than none at all!
A bubble test is an important safety measure if you ever disconnect your propane lines at RV appliances or to your regulator. Our technicians are instructed to do this after performing any maintenance regarding your RV’s propane system, as well as when prepping new and consigned RVs for sale.
You are also correct in noting the incorrect orientation of the assembly in the video and that photo. We turned it around in the video to make it easier to display, but that should be noted in the article below. We’ll update it! The reason it should be facing toward the trailer is to protect it from rocks and other flying debris when you’re towing.