The 30-gal propane water heater in our cabin made a sound like a small explosion (equivalent to about 5 times the volume of a normal "fire-up") which got our attention. The front had begun to blacken above the access panel after starting to use the last 25# tank; the flame is mostly orange with only about 1/2" of blue. The orange flame also curls and overlaps the tank bottom and there is charred debris in the chamber and on the floor. This is only a 27000 BTU tank in an open room with more than ample oxygen sources for combustion from both back and front of the unit. The vent is short, about 5 feet, and appears to be clear. The unit had been working normally. The owner's manual is no help. We switched tanks; switched regulators on the tank(s); same thing. The pilot relights easily, it started up normally twice, but the flame is still wrong. Getting service on location is impractical; choices are to uninstall it and take it to service or just replace it but don't want to give up yet as it's had less than 3 years of use (though a lot of 1 week use followed by 3-4 weeks off). The mix of air and fuel is wrong; can anyone suggest what can be wrong?
Altitude is 479 ft; temperature range was 59-80F. Tanks are left outside and changed out as needed - could there be debris in the line?
The burner itself may be stopped or the ports may have dirtdobbers nest in holes if this is a vacation resort home. take an air tank and blow the burner itself out good and clean.it may have lint in the throat or burner port.after cleaning burner properly, the air butterfly should be turned aprox 1/4 turn from full close. I would be very careful with this, as propane gas lays on the floor and is very explosive. also, if the tanks are liquid full, or the diaphram in the regulator is blown, this will also occour.