I'm at my wit's end with my 1999 Beaver DP's propane detector! This thing keeps triggering false alarms, especially when I park in my garage. Even with the LP tank completely shut off, the alarm still goes off within hours. It's located in the bottom of the fridge cabinet.
I've checked everywhere for actual leaks - can't smell anything, and all my appliances still light immediately when I take the RV out. The detector seems fine outside but becomes a nightmare indoors. I'm wondering if it's the sensor going bad, poor placement, or if there are other things that can trigger these detectors besides actual propane leaks?
I really need a complete breakdown of what causes these false alarms and how to fix this issue once and for all. Should I be looking at replacing the detector entirely, or are there troubleshooting steps I'm missing?
Fix LP gas detector false alarms in RVs. Covers trigger sources, sensor age, proper placement, and when to replace your propane detector.
Your 1999 Beaver DP is experiencing a classic garage phenomenon - the LP detector in your fridge cabinet is likely responding to small amounts of propane that naturally seep from your system and accumulate in the enclosed garage environment. Even with the gas shut off at the tank, residual propane in the lines slowly leaks out through imperfect seals (as you correctly identified with your stove valves). In your 40x15x16 garage, even minimal air circulation allows these trace amounts to concentrate near floor level where your detector sits, while outside wind disperses them immediately. While this may be minor seepage rather than a major leak, all sources of propane leakage should be identified and eliminated to ensure system safety.
The primary culprit is the natural settling of propane vapor, which is heavier than air and pools in low areas like your fridge cabinet location. Your observation about the stove valves is spot-on - every connection point in an LP system has microscopic seepage, including regulator diaphragms, appliance shut-off valves, and threaded fittings. In a 24-year-old coach like your Beaver, rubber seals and gaskets have aged and allow slightly more seepage than when new.
The garage environment exacerbates this issue because enclosed spaces prevent natural air circulation from dispersing these trace amounts. Even shutting off the main tank valve doesn't eliminate the problem because propane remains in the lines between the tank and your appliances - typically 20-30 feet of piping in a motorhome. This trapped gas slowly migrates through connections over several hours, explaining why your alarm triggered even after closing the tank valve.
Your detector placement in the bottom of the fridge cabinet creates a perfect collection point. RV manufacturers typically install LP detectors low because propane settles, but this also means they're more sensitive to accumulated vapors in enclosed spaces. The fact that your appliances light immediately when you take the coach out confirms the system holds pressure well - you're dealing with normal seepage, not a significant leak.
First, understand that some LP seepage is normal in any propane system, and your detector is doing its job by alerting you to accumulated vapors. However, you should verify this is seepage rather than a more significant leak. Check that your LP detector is functioning properly - most RV detectors have a test button that should trigger the alarm. If it doesn't respond to testing, replace it before proceeding with any diagnostics.
Gather a spray bottle with soapy water (dish soap mixed with water) and consider investing in a handheld combustible gas detector. The cheap Amazon detectors you mentioned can be useful supplemental tools - models like the Techamor Y201 ($30-50) or UEi CD100A ($40-60) provide good sensitivity for hobbyist use, though they're not as precise as professional equipment. These handheld units help you pinpoint specific leak locations rather than just detecting accumulated vapors.
Document the timing of your alarms - note how long after parking in the garage the detector triggers. This information helps distinguish between rapid leaks (immediate alarm) versus normal accumulation (several hours). Also, check if the alarm occurs in the same location within the garage, as this might indicate air circulation patterns affecting vapor concentration.
Before beginning any leak detection procedures, ensure no ignition sources are present - extinguish all pilots, avoid electrical switches, and eliminate any open flames. Start your leak detection at the most common failure points in your 1999 Beaver. Begin with the regulator - the diaphragm and vent hole often develop small leaks after 20+ years. Ensure all appliances are OFF and any pilot lights are extinguished. With the system pressurized, spray soapy water around the regulator body, vent hole, and inlet/outlet connections. Look for bubbling that indicates escaping gas. A replacement regulator typically costs $40-80 and takes about 30 minutes to install.
Next, check all appliance shut-off valves, particularly at your range/oven, water heater, and furnace. These brass valves develop seat leaks over time, especially if they're not operated regularly. Apply soapy water to the valve stems and outlet connections while the system is pressurized. If you find leaking valves, replacement typically costs $15-25 per valve, and most are accessible without major disassembly.
Inspect threaded connections throughout the system, paying special attention to the connection at your LP tank, any unions in the piping, and connections at each appliance. Don't forget to check the connection where your LP supply line meets the coach's hard piping - this fitting often loosens from road vibration. Minor connection leaks may require tightening, but this should be done according to manufacturer torque specifications and followed by proper leak testing to verify the repair.
For your garage storage situation, consider installing additional ventilation. A simple exhaust fan on a timer can create air movement that prevents vapor accumulation. Alternatively, crack a window or door slightly to maintain air circulation. Do not disable your LP detector when storing in garages, as this creates a dangerous situation where accumulating gases cannot be detected even if a leak develops.
Contact a certified RV LP technician if your soapy water testing reveals any steady bubbling at connections, or if tightening fittings doesn't resolve minor leaks. Professional leak detection using electronic sniffers can identify leaks as small as 50-200 parts per million, far more sensitive than your nose or soapy water testing. A typical LP system inspection costs $150-250 but provides peace of mind for a 24-year-old system.
Seek immediate professional help if you detect any of these warning signs: rapid alarm activation (within 30 minutes of parking), strong propane odor anywhere in the coach, or visible damage to LP lines or connections. Additionally, if your testing reveals multiple leak points or if appliances begin having ignition problems, it's time for a comprehensive system evaluation.
Consider professional regulator replacement if yours is original to your 1999 Beaver. After 25 years, even properly functioning regulators often develop minor internal leaks that aren't immediately dangerous but cause storage issues like yours. A certified technician can also perform a complete system pressure test and inspect hard-to-reach piping runs that might have developed issues from road vibration or aging.
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