Alarm keeps going off - help

[rodigio]

We just got back from 6 days in Fishlake National Forest. Everything went well except the carbon monoxide alarm was driving us crazy.
Every time the wind would blow toward the water heater side of the trailer, the alarm would go off. We had all of the doors and windows open, and even the loading ramp (patio) open, and the breeze was flowing throughout the inside, so we know there was no buildup of co2 inside the cabin, yet the alarm would always go off every time we turned on the water heater.
When the wind was calm there was no alarm and all was well.
Any ideas ?

[A32Deuce]

The exhaust from the propane water heater was setting it off. When I have my unit at home and someone parks near with the engine running and I have the door open, mine goes off. Windy days if blowing the right way, mine will also go off. Now if its close to 5 years old and goes off and nothing is on and it beeps, time for a new one.