Mine went off when the humidity in the trailer rose very quickly. The trailer was hooked up at home to city water and electric. The system was filled with water, the water heater was full and lit. I had shut off the water going to the trailer. It was off for about 3 days. While inside the trailer I turned on the cold water faucet at the kitchen sink. Very hot water came out until the pressure bled off. I went outside, turned off the water heater, turned the water to the trailer back on then opened the hot water faucet to let the very hot water out of the tank. The humidity in the trailer went up quickly since it was cool inside when I ran all the hot water out of the tank. The propane detector went off several times with me hitting the alarm silence button a few times until the humidity dropped off.