RV Propane System Inspection Checklist: Tanks, Regulator, Leak Test, and Detectors

Propane runs the furnace, the water heater, the cooktop, the refrigerator when you're off shore power, and on some rigs the generator. It's also the system almost nobody inspects until something smells or won't light. Nobody sells a "propane service" the way they sell an oil change, so tanks sit for a decade, regulators drift out of spec, and mud daubers nest in burner tubes over the summer.

Here's the annual walk-through — before heating season is the natural time. Budget 45 minutes, a spray bottle, a wrench, and a flashlight.

Start at the tanks: dates, valves, and rust

Removable DOT cylinders — the 20, 30, and 40 lb bottles on trailers and fifth wheels — have a manufacture date stamped into the collar as month and year, so 06 14 is June 2014. A cylinder is good for 12 years from that date, then needs requalification, which typically buys another 5 years. An expired bottle isn't dangerous sitting in your rig, but no reputable dealer will refill it — a miserable thing to learn on a Friday night in October.

While you're down there:

• Confirm the valve has an OPD (overfill protection device) — a triangular handwheel, not the old five-pointed star. Cylinders without one haven't been fillable since 2002.
• Check the foot ring and bottom seam for rust. Surface rust wipes off and takes paint; pitting you can catch a fingernail in condemns the bottle.
• Make sure the bottle sits level and its bracket is tight. One that rocks in its holder chews through the pigtail hose.

ASME tanks — the permanently mounted horizontal tanks on motorhomes — never expire and never need requalification. What fails is the gauge, the valve packing, and the mounting straps, so get underneath and inspect the straps and the tank's underside where road spray does its work.

And fill to 80%, not full — that empty top fifth is the vapor space the system needs, and a liquid-full tank sends propane into the regulator.

The regulator is a wear part, and yours is probably overdue

This is the most overlooked component in an RV. The two-stage regulator takes tank pressure — 100–200 psi on a hot day — down to about 10 psi, then to 11 inches of water column (roughly 0.4 psi), the only pressure your appliances are built to burn. It's a rubber-diaphragm device living outdoors, and most manufacturers rate its service life at 10 to 15 years.

• Age. Look for a date on the body or a sticker. Over 12 years old, or no date at all, means budget to replace it — usually $40–$90 plus an hour of labor.
• The vent. It must point down, within about 45 degrees of vertical, so rain and road spray can't sit in it. A vent facing up freezes shut in winter and starves every appliance at once.
• The cover. The plastic hood over the regulator isn't cosmetic — missing covers are why regulators die early.
• The changeover indicator. Red on a full pair of bottles means it's stuck.

The failure pattern is unmistakable once you know it: several unrelated propane appliances get weak at once. Lazy yellow flames, a furnace that lights then locks out, a fridge that won't hold temperature on gas — and owners chase each one separately for months. A manometer on the test port settles it: 11 inches static, holding near 10.5 with two or three appliances running.

The leak test that actually proves something

Do this outdoors, no flame anywhere near, engine and generator off.

1. Mix dish soap and water about 1:4 in a spray bottle. Skip the aerosol leak detectors containing ammonia — ammonia attacks brass fittings.
2. Open the tank valve slowly, all the way, then back off a quarter turn.
3. Spray every joint from the tank forward: the POL or ACME tank connection, both ends of each pigtail, the regulator inlets and outlet, and every threaded joint you can reach under the rig.
4. Watch each joint for 30 seconds. A leak grows a cluster of fine bubbles that keeps expanding. One big bubble that pops and doesn't return is just air.
5. Rinse the soap off afterward — it corrodes brass.

The rubber pigtails between tank and regulator are consumables. Flex each one looking for surface cracking and check the date stamp — five to ten years is a reasonable replacement window, sooner in Arizona or Texas sun.

What soap can't find is a leak inside a wall or under the floor. That takes a timed pressure test, where the system is pressurized and has to hold without dropping — the right call any time you smell propane and can't source it, or after work that opened the line.

If you smell gas: shut the tank valve, open windows and roof vents, get everyone out, and don't touch a light switch or start the engine. Propane is heavier than air and pools in the floor cavity and basement bays.

Burner tubes, flame color, and the nests behind most no-heat calls

Every propane appliance draws combustion air through an open tube, and every one of those tubes is an attractive place for a mud dauber or spider to build. It is genuinely the most common cause of the no-heat and no-hot-water calls that come in each fall.

Pull the outside access doors on the water heater and furnace and look into the burner tube with a flashlight, watching for a rust-colored mud plug or a cottony web. Compressed air or a bottle brush usually clears it, and a stainless bug screen keeps it from coming back. Do the same at the refrigerator's lower outside vent, where the flue and burner live.

Then look at the flames. Healthy propane burns crisp blue, maybe with a faint yellow tip. A lazy orange flame that dances means incomplete combustion — a restricted intake, dirty orifice, or low pressure — and incomplete combustion is what makes carbon monoxide. Soot on a cooktop grate or streaking up an exterior wall above a vent is the same message written outside. Stop using the appliance. If it's the water heater, our guide to diagnosing the gas and electric sides separately will narrow it down before you call.

Your LP and CO detectors have expiration dates

Both alarms are consumables, and the test button doesn't test the sensor — it only confirms the horn and power.

• LP gas detector: mounted inches off the floor because propane sinks. Most are rated 5 to 7 years from the manufacture date on the housing, around $40, hardwired to 12V. One that chirps or false-alarms is usually announcing end of life — but treat every alarm as real until you've checked.
• Carbon monoxide alarm: 5 to 10 years depending on model, with a replace-by date on the label. Combo units expire on the shorter clock.

Write the replacement year on the housing when you install one.

When to call a pro

Owner-level work stops at the regulator. Everything downstream is fixed piping and appliance gas trains, where the failure mode is fire or CO, not inconvenience. Call a tech when:

• Bubbles show a leak you can't fix by tightening a fitting.
• You smell propane but every visible connection tests clean — that's an internal line or appliance valve, and it needs a pressure test.
• An appliance still burns yellow or sooty after you've cleared the burner tube.
• The regulator is over 12 years old or several appliances went weak at once.
• The furnace lights and locks out repeatedly — often a sail switch or gas valve rather than supply. See RV furnace repair in Fort Collins.
• An appliance runs on electric but not gas — start with RV water heater repair in Phoenix or RV refrigerator repair in Denver, or browse the RV repair hub.

FAQ

How often should an RV propane system be inspected? Do the owner-level walk-through — tanks, regulator, hoses, soap test, burner tubes, detector dates — once a year, ideally before heating season. Have a tech run a timed pressure test every few years, and always after line work or a hard impact underneath the rig.

Is it safe to drive with the propane on? Mechanically yes — excess-flow valves and the regulator are built for it. But an open flame during a collision or fuel stop is a real risk, and many tunnels and bridges prohibit it outright. Shut the valves before fueling; a well-packed fridge holds temperature six to eight hours closed.

Can I replace an RV propane regulator myself? The swap is straightforward with two wrenches and propane-rated thread sealant (never Teflon tape on flare fittings). What you can't do at home is verify outlet pressure afterward, and a regulator set wrong soots every appliance you own.

Propane trouble surfaces on the first cold night of a trip, and it's not the kind of thing to guess at. Call 833-FIXED-RV (1-833-349-3378) — one call, answered live 24/7, and we connect you to a vetted, licensed, insured local tech who can leak-test the system and set the regulator properly. Their work is backed by our $2,500 Workmanship Guarantee, and the call is free to you.