RV 101: Intro to the Propane System

Welcome to the RV 101 Series! In this series, I briefly introduce you to all of an RV’s major parts and systems:

  • Chassis
  • House & Slides
  • Cabinetry
  • Appliances
  • Electrical (AC+Generator and DC)
  • Plumbing – Fresh
  • Plumbing – Waste
  • Hydraulic (opt)

Each post is a simple, non-technical introduction to how an RV works (and sometimes, why it doesn’t). If you’re new to this website, you should start here!

Propane is the lifeblood of many RVs. As coursing blood in the body heals and energizes, so does propane carry warmth, enable refrigeration, and help cook. It’s cheap and abundant – but also easily abused or mishandled. Treat it with respect.

This is a 101 guide to your RV propane system. You will learn why RVs use propane, how it works, what parts are required, and how to safely use it.

Hello! Meet Propane.

First of all, for our purposes, LP = propane. LP technically stands for Liquid Propane, which is typically in a pressurized state.

Propane is produced by refining natural gas. At standard temperature and pressure, it is a gas. Under high pressure, however, it transforms into a liquid.

Propane is naturally odorless and colorless. It’s also highly flammable, even combustible, so refiners add a sulfurous-smelling compound so we humans can sniff out leaks.

Propane is available almost anywhere in the country. Retail stores and convenience shops may even have propane tank exchange stations, where empty DOT 20-lb tanks can be quickly swapped out for full tanks. Other tank sizes can be refilled at certified refill stations.

How Does My RV Propane System Work?

Simplified, an RV propane system is just three big parts:

  1. Storage tank
  2. Pressure regulator
  3. Manifold

The tank stores the liquid propane at high pressure.

The pressure regulator drops the high pressure propane in two stages down to a final line pressure of 10-14” w.c (about 0.4 psi). The drop in pressure vaporizes the liquid propane into gas.

A manifold system, usually made of either black iron pipe, copper tubing, or thermoplastic hoses, distributes the gaseous propane to the individual appliances.

Appliances that commonly run on propane include:

  • LP-powered furnace
  • Absorption refrigerator
  • Range or cooktop
  • Water heater
  • Oven

These appliances combust the propane and use the heat.

  • Some appliances, like a stove, apply the heat directly.
  • Others, like a furnace, pass the heat through a heat exchanger.
  • And still others, like a refrigerator, use the heat as an “engine” for a chemical or mechanical process.

All of these appliances must be vented to the outdoors. Burning propane consumes oxygen and produces toxic fumes, which must be removed from the RV interior.

Appliances like your microwave and air conditioner DO NOT use any propane whatsoever.

Let’s work through the three main system components one at a time.

Storage Tank

Most motorhomes use built-in ASME tanks, regulated by the American Society of Mechanical Engineers.

ASME Propane Tank for RVs
Example of ASME mounted propane tank.

Most travel trailers and fifth wheels use removable DOT cylinder tanks, regulated by the Department of Transportation.

Dual DOT Propane Cylinders on Travel Trailer A-Frame Tongue
Examples of DOT portable tanks.

How much does propane weigh?

Propane weighs about 4.2 lb/gal at standard conditions.

How many gallons does a propane tank hold?

Here are the typical volume capacities per tank size:

  • 20# tank: 4.6 gallons
  • 33# tank: 7.8 gallons
  • 40# tank: 9.4 gallons
  • 100# tank: 23.6 gallons

Tanks should not be filled all the way! Some empty space is required for thermal expansion and pressure buildup.

Where is the propane tank on my RV?

Wherever they are located, propane tanks are required to be separated and sealed from the interior living space.

  • On a travel trailer, check on the front tongue.
  • On a fifth wheel, check the cargo compartment in the front of the camper body.
  • In a motorhome, check the basement under the coach near the other mechanical systems and equipment.

What are OPD valves on my propane tank?

OPD stands for “Overfill Protection Device.” These valves prevent any station or user from filling more than 80% of the bottle capacity.

In April 2002, DOT required that all propane bottles with capacities of 4-40 pounds must have an OPD valve.

Where to refill my propane tanks?

You can find propane refill stations at many RV parks, U-Haul locations, Camping World dealerships, truck stops, construction Big Box stores, and convenience stores.

Some of the Big Box stores include Menards, Costco and Home Depot.

Popular chains include AmeriGas, Ferrellgas, and Blue Rhino. Other chains include U-Haul and Tractor Supply. Geographic regions typically have regional favorites, too.

Do an internet search for “propane refill stations near me.” You can also search the digital Yellow Pages for your locale.

How much does a propane refill cost?

The price of propane is measured on a per-gallon basis. It fluctuates based on the market, quantity, and region. As a rule of thumb, as the price of crude oil increases, so does the price of propane.

Costs tend to be lower in the transition months during spring and autumn. Avoid the peak heat of summer or the frigid doldrums of winter.

You’ll pay more to refill your RV propane tank compared to refilling your 250-gallon residential tank. As of this writing, expect to pay $3.00 – $4.00 per gallon at most chain propane refill locations.

Should I exchange or fill my propane tanks?

In the long run, it is cheaper and more efficient to fill your propane tanks rather than swap out empty for full.

You can save $1.25 – $2.00 a gallon by refilling rather than exchanging!

Plus, unless you have 20-lb tanks, it can be difficult to find swap-out locations for 30 pound and larger tanks.

Please note that you don’t usually receive any credit or discount for any propane leftover in your tank if you exchange! However, if you refill, you’ll only pay for the propane actually replenished.

Does my propane tank need to be recertified?

Portable DOT tanks are required to be recertified 12 years from the date of manufacture and then every 5 years.

ASME tanks do not have a mandatory recertification period.

Also, every DOT tank is required to have an OPD valve to relieve pressure. If you’re using an obsolete-style tank with a POL valve, please have it retrofitted and re-certified for your safety!

ASME tanks can only be refilled, not exchanged, since they are not portable.

Pressure Regulator

Example of a dual-stage single-tank propane regulator.

How does my RV regulator work?

Pardon the terrible pun, but your propane tank really is built “like a tank.” A portable RV propane tank can survive internal pressures as high as 350 psi before the safety valve opens.

Your RV regulator controls the output pressure. Most modern RVs use a 2-stage regulator.

  • The first stage vaporizes the propane and lowers the output pressure to around 10-15 psi. For reference, that’s about the inflation pressure of an NFL football.
  • The second stage lowers the output pressure to about 11 inches of water column, which is around 0.4 psi. It’s not much!

All propane-burning RV appliances are rated for operation at 10-14” w.c.

What are inches of water column?

Inches-water-column isn’t a measurement you typically use! Long story short, technicians use a water manometer to measure the LP gas line pressure. So in. w.c. is most convenient.

For reference, 11” WC is around 0.4 PSI! Hardly any pressure at all. For reference, an outdoor camping stove typically runs propane at around 10-15 psi.

By the time the liquid propane in the tank has been delivered to the first stage, it has vaporized into a gas. Propane at low pressure is much safer than at high pressure. That’s why it’s allowed to be run inside your RV.

How do I know if my propane regulator is broken?

Keep an eye out for these signs of a failing propane regulator:

  1. Orange (instead of blue) flames at the stove cooktop.
  2. Leaky regulator – will smell like rotten eggs.
  3. Dark soot – propane should burn cleanly.
  4. Loud hissing noises from the regulator or popping noises from the appliances.
  5. Automatic switchover quits working.
  6. LP-powered appliances won’t ignite or turn on.

How do I reset my LP regulator after a lock up?

When a regulator detects a high rate of propane flow, it will automatically enter a very low-flow state (regulator lockup).

Resetting a propane regulator is easy!

  1. Turn off all your propane appliances.
  2. Close the tank valve.
  3. Wait 30 seconds to 2 minutes.
  4. Open the tank valve.

3 Things You Must Know About Your RV Propane Regulator

Carry a spare

1 Regulators usually need to be replaced every 5-10 years. Without a working regulator, half the appliances in your camper will shut down. Average cost of a regulator is $25 – $50.

Clean the vents

2 A 2-stage regulator has two vents. First-stage vent is just a tiny hole in the housing. The second-stage vent is a dime-sized perforated screen. Verify that these vents aren’t clogged up!

  • You might need a paperclip to ream out the first-stage pinhole vent.
  • Verify that the second stage vent faces downward.
  • If your pressure regulator doesn’t have a plastic cover, it should.

Cover it up

3 Dual-stage regulators should have a cover to protect them from road damage and any debris. This is in addition to the bottle cover that protects the tanks themselves.


Your LP manifold delivers propane gas to your individual appliances. It’s a hidden system of pipes, tubes and fittings.

Usually, your manifold runs underneath your RV floor. It may be enclosed by your underbelly cover, but it must be accessible without removing structural members.

What is my propane manifold made of?

Pipe & Hose

Most RV manufacturers use black iron (steel) or copper tubing to plumb the LP manifold system.

Today, thermoplastic hoses are becoming the new standard. These hoses connect using conventional brass fittings or patented low-pressure quick-disconnects.

Plumbing an LP system is not like plumbing for water. Special pipe dope is required for brass connections. Double flares are required at all copper connections. There are dozens of requirements for maximum unsupported span, accessibility of shut-off valves, etc.

Your RV may have individual shut-off valves for your appliances or not. If your RV does have shut-off valves, they are required to be accessible for use and service.


2 You’ll normally find brass fittings in your manifold.

The medium- and high-pressure sides of your distribution system will typically use conventional brass fittings (elbows, tees, etc.) with NPT threads. Special pipe dope or tape is required for use with propane gas distribution systems – you can’t just use white Teflon tape!

The low-pressure sides of your distribution system (downstream of the second stage of the regulator) may use conventional brass fittings or patented low-pressure quick-disconnects.

Propane Safety

Michael Huff, a full-timer, wrote an in-depth article about basic RV propane safety. You can find it here. Here are the basics of what you need to know.

LP Detector

The heart of your propane detection system is a small electronic detector mounted somewhere close to floor level. It’s your LP detector, commonly bundled with your CO2 (that’s carbon monoxide) detector as well.

Propane gas is heavier than error. Any leaking glass will pool onto the floor. So by the time it reaches the level of your nose, you’re in extreme danger.

Common sources of propane leaks are your cooktop stove and absorption refrigerator. Leaks inside your camper, at low pressure, are usually invisible. Leaks of high pressure propane are normally visible as a frigid white fog.

An LP detector will sound an alarm if it detects unsafe conditions. Never disable or cover your LP detector! Unlike your smoke alarm, which usually runs off batteries, the LP detector is usually hardwired into your 12V electrical system, powered by your battery. If you remove your battery or turn on the disconnect switch, the LP detector will not work off-grid.

Annual Inspections

The importance of an annual inspection of your propane system cannot be overstated. The entire system – tank, regulator, and manifold – should be carefully inspected for any signs of damage, abuse, or unacceptable wear and tear.

Leak testing can be performed on hoses, pipes or fittings using a bubble leak detection fluid (or soapy water) or a timed pressure-drop test.

The LP detector should be tested annually as well. An RV technician will have a can of compressed propane gas to lightly spray in front of the detector to check its functionality. Leak detectors should be replaced every 5-10 years or in accordance with the manufacturer’s instructions.

Ventilate Closed Spaces

When propane combusts or burns, it consumes oxygen. It cannot be safely combusted within an enclosed space.

When using your gas cooktop, you should turn on the range hood or crack open the kitchen window.

Also ensure that the back of your absorption refrigerator has no air entryway into the interior of the RV. The combustion gases from the refrigerator ought to be vented directly into the outdoors.

If you operate a propane catalytic heater inside your RV like a Mr. Buddy or Olympic wave heater, these heaters should come with low oxygen shut-off sensors. Either way, you should turn on a fan or open a window to ensure fresh air circulation.

What To Do In the Case of a Leak?

  1. If you smell or suspect a propane leak, immediately open the RV entry door any any nearby windows or fans. Turn off your stove, water heater, and any other fuel-burning appliances. Do not light a match or lighter of any sort unless you want to turn into a human firework.
  2. Get out of the RV and turn off the tank[s] shut-off valve. Stay at least 50 feet away from the RV.
  3. Wait at least 15 minutes before re-entering the camper.
  4. If necessary, consult a certified RV technician for help.

One response to “RV 101: Intro to the Propane System”

  1. After reading this article, I now have a better idea of what to do to prepare our camping vehicle to use propane. Storage and safety were two things that I really wanted to work on as that could be exactly the kind of thing that we need to think about as we use that to avoid any issues. Once I find a home propane expert in the area, I’ll get them to help with the proper installation of that fuel source.

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