Thursday, November 30, 2023


Know Your RV: Using your propane regulator

Having hot water, a stove that works, and heat when the temperature goes down is great. For RVers, propane makes all these good things possible. Do you have a travel trailer or fifth wheel? Then your propane (or LP, for “liquid petroleum”) is kept safely stored under high pressure in LP cylinders—most likely two of them. That storage pressure has to be reduced to a much lower level, and that job is done by a propane regulator. It’s a low-maintenance item, but it does require your attention.

Sight-glass indicator tells all

Indicator flag at top is green. Shows full cylinder to the left. R & T De Maris photo.

Most “towable” RVs have two removable LP cylinders. When one empties out, an automatic change-over regulator will simply start drawing on the other cylinder. An indicator in the regulator’s sight-glass will show you that you have an empty cylinder and it’s time for a refill. With this kind of regulator, you can take the empty away, leaving the other hooked up, keeping stuff like the refrigerator operating. No need to move the RV to refuel the propane.

How does the indicator work? While your regulator may look different, automatic changeover regulators are basically the same. Notice at the top of the photo there’s a small cylindrically shaped item. That’s the sight-glass—you’ll see it has a strip of green in it. Below it is a large knob with a “pointer” pointing to the left. That’s the cylinder selector lever. The sight-glass indicator is keyed to whichever cylinder the lever points to. In this case, the sight-glass, showing a green flag, indicates the left cylinder still has gas in it. If the indicator were red, it would mean that cylinder is empty. Some older regulators may use a silver-colored flag to indicate gas, with a red flag indicating empty.

Change out that empty!

Here’s how to change out an empty cylinder. When the sight-glass indicator shows you have an empty, TURN the lever (or the pointer knob) of the regulator toward the “full” bottle. Then TURN OFF the empty container supply valve, turning it completely clockwise. Now you can safely remove the empty container by disconnecting the rubber “pigtail” or connector hose. Twist the plastic connector at the bottle end of the pigtail counterclockwise.

When you bring the refilled cylinder back, slip it into place, connect up the pigtail, turning it clockwise. What we do now is flip the selector lever and point it to the “fresh” cylinder. What will happen is that if an appliance is drawing LP, the indicator flag will turn red. We then open the supply valve on the top of the cylinder, SLOWLY. At first just barely “crack open” the valve, then go ahead and open it the rest of the way. In some cases if you just blast open the cylinder valve, a safety device inside the pigtail will shut down the flow. The indicator flag should now turn green. That means you didn’t accidentally kick-in that pigtail safety, and gas is flowing from the newly refilled cylinder.

What if the indicator still shows red? First, make sure there is a demand for gas. Light a burner on your range. Now check the flag. If it’s still red, you’ve likely triggered the pigtail safety. Close the valve on the refilled cylinder and disconnect its pigtail. That should allow the safety to reset. Reconnect the pigtail and repeat, opening the cylinder valve slowly. Once you’ve assured yourself that you have gas flow from the “fresh” cylinder, be sure to flip the tank selector lever back to the other cylinder.

A regulator will tell you if you’ve sprung a leak

Vent clearly marked. photo.

Automatic changeover regulators are not only useful in keeping you in gas, they can also tell you if there’s a leak in your RV propane system. With all propane appliances in the RV turned off and no pilot lights left lit (or turned on), turn off the gas valves on your propane containers. At this point, the regulator sight-glass flag should show “full.” Keep an eye on it and within a few minutes (or even a few hours) if the sight-glass flag shows “empty,” it’s a safe bet there’s an LP leak somewhere in your system. Have your system checked immediately!

LP regulators don’t require a lot of attention. You need to keep safety first. Your regulator has a vent, and it will be clearly marked as such, as you can see from the picture. The vent must always be pointed DOWN. Vents are equipped with a screen-like material to keep dirt and bugs out. Keep the screen clear to allow the regulator to breathe, and in case of malfunction, to blow off excess pressure. Keep water out of the vent by keeping the regulator covered and out of the elements. Notice the indicator flag on this regulator isn’t at the top, but in the middle.

Happily, regulators are happy creatures. Keep the vents clear, and know how to change out empty cylinders and life will be good.

Other stories by Russ and Tiña De Maris

Updates: 09/19/2022 4:57 PM. Corrected error on which end of the hose to twist the connector. 


Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.



4.8 6 votes
Article Rating
Subscribe to comments
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Oldest Most Voted
Inline Feedbacks
View all comments

Tommy Molnar (@guest_259850)
24 days ago

I’ve gone to shutting off the tank that is not being used. That way, when the currently used tank runs dry and stuff doesn’t work, I know it and can get it filled. Yes, it can be a PITA, but I won’t unknowingly run completely out of propane in both tanks.

T. Hudson (@guest_259914)
23 days ago
Reply to  Tommy Molnar

That’s what I have always done. For the same reason you stated.

Jim Johnson (@guest_259825)
24 days ago

I have encountered a lot of trailer RVers who simply don’t know about automatic change over regulators or don’t think they are safe. They leave the secondary tank valve closed. And when the primary tank empties, they close that valve, flip the lever on the regulator and open the secondary tank.

It’s another one of those myths discussed around a shared campfire that starts with a complaint about heading outside in the middle of a cold night..

Bob M (@guest_259815)
24 days ago

Jayco installed my propane regulator so you can’t see if a tank is empty. When they had the regulator recall the dealer installed the new regulator the same way. Too cheap to use a longer hose.

Jeff Arthur (@guest_259844)
24 days ago
Reply to  Bob M

Mine is also installed in this manner.
I use my phone to take a picture to see the indicator. Definitely not ideal

Robert Champlin (@guest_202681)
1 year ago

Our regulator on our 2018 Vanleigh Vilano has always appeared to be operating correctly. Recently I’ve noticed that the green/red indicator is staying red all the time. We have been in one location since April in Oklahoma. I’ve had both tanks full and we haven’t had any problems with the stove. Does anyone have any idea what might be causing this and/or how to correct the situation, or do I just need to get a new regulator.

Russ De Maris (@guest_202703)
1 year ago

Robert, sounds like your regulator has given up the ghost. Last attempt, close both cylinder valves, disconnect the pigtails from the cylinders. Then reconnect everything as mentioned in the article. If you still have a red flag on a cylinder you know has fuel, time for a new regulator.

Sign up for the

RVtravel Newsletter

Sign up and receive 3 FREE RV Checklists: Set-Up, Take-Down and Packing List.