Every RV detector has a service life printed on the back, typically five to seven years from manufacture for propane sensors and up to ten for some CO sensors. The exact date is printed on your unit. When it reaches that date the unit will start chirping or flashing an end-of-life code, and some models disable themselves. Owners then pull the fuse to stop the noise, and the camper runs with no detector. This guide gets a new one in within half an hour.
Which detector
There are three families:
- 12 V hardwired dual LP/CO. Powered from the RV's 12 V system, mounted low on a wall. This is what most RVs and every Black Series HQ ship with. Options: the Dometic Atwood 31011 CO & LP detector ($44.99), the dual LP/CO alarm, 100 dB, 12 V ($42.00), or the 12 V LP & CO detector with three brackets for flush or surface mount ($75.00), which is the easiest cross-brand replacement.
- 12 V propane-only. If the RV has a separate CO alarm, a propane-only unit like the R501 hardwired LP detector ($34.99) or the compact 85 dB unit ($45.00) drops in.
- Battery-powered CO. Mounted high, no wiring. A 10-year battery CO detector ($50.00) is the right backup for any RV with a generator, diesel heater, or propane furnace.
The detector buyer's guide compares them in detail. Measure the old unit's cutout and screw spacing before ordering; a unit that covers the old hole saves patching the wall.
Where it goes
Propane is heavier than air and pools near the floor. Carbon monoxide mixes with air and is usually detected best at breathing height or higher. A combined LP/CO unit is therefore a compromise: mount it exactly where its own manual says, which for most dual units is low on the wall, 4–20 in above the floor, away from the stove, the door, and anything that blows air on it. A separate CO alarm goes high, near the sleeping area.
Tools
- Screwdriver
- Wire strippers and crimp connectors
- Multimeter or test light
- Small inline fuse holder if the old circuit has none
Time: 20–40 minutes.
Step 1: Confirm the circuit and kill it
Find the detector's fuse at the 12 V panel; it is often labeled and often shared with something else. Pull it. Check with a test light at the old detector's wires that power is gone.
Step 2: Remove the old unit
Remove the face screws, pull the detector out of its cutout, and unplug or cut the wires. Read the label on the back and note the manufacture date for your records. Dispose of it; an expired detector left in a drawer ends up back in a camper.
Step 3: Wire the new unit
Most 12 V detectors have two wires: red positive and black negative. Some have a third for an external relay or a solenoid valve output. Strip, crimp, and heat-shrink positive to positive and negative to negative. Do not rely on push-in connectors that came with a household unit.
If the old circuit was unfused or shared with a large load, add an inline fuse sized to the rating printed on the detector, typically 1–3 A. A detector that shares a circuit with a water pump will see voltage sag every time the pump runs and may false-alarm.
Step 4: Mount and power up
Push the wires in, screw the unit to the wall, and restore the fuse. Nearly every LP/CO detector runs a warm-up of one to several minutes during which the LED shows a status color; do not test until it settles.
Step 5: Test properly
Press and hold the test button until the alarm sounds. That checks the circuit and the horn, not the sensor. For a real sensor test on the propane side, use an unlit lighter held near the sensor grille for a few seconds; the alarm should sound within a short time and clear when the gas disperses. Do not test the CO side with exhaust. Record the date on a label on the unit.
Why it kept going off before
If you are replacing a detector because it kept false-alarming, check the causes first: low battery voltage (many units alarm below about 10.5 V, so check yours), aerosols and cleaning sprays, a fridge vent leaking exhaust into the cabin, a full black tank venting inside, or a dog sleeping against it. New detectors will do the same thing if the cause is still there. If the alarm was for propane, leak-test the system with soapy water at the regulator, pigtails, and every appliance connection, and replace anything suspect, such as the gas hoses or changeover regulator.
Complete the safety set
While you are at it: check the smoke detector ($50.00) battery, the fire extinguisher ($90.00) gauge, and if you run a generator, keep a portable travel CO detector ($69.00) in the bedroom as a second layer.
Shop this
- Dometic Atwood 31011 CO & LP Detector, 12V — $44.99
- Dual LP/CO Alarm, 100 dB, 12V — $42.00
- RV Propane & CO Detector 12V, 3 brackets — $75.00
- Smoke Detector — $50.00
- RV Safety Detectors (collection)