I have had a tankless water heater for about 4 years.. I love it but it is constantly building up a white powder inside the flame area. The powder corrodes the flame sensors so every month or so I have to pull of the cover, blow out the powder, and use sandpaper on the sensors I can reach.

The company can not explain what the white powder is. I have had a heating and cooling specialist out a few times and he says it is something in my propane. I called my propane company and they said it isn't their propane or anything they put in the propane.

Does anyone else have this problem or have any idea what this powder might be or how to stop it from building up like this.