Ok, first there was horrible black smoke, but the water got hot, so I kept running it until a nieghbor actually complained. (Yeah, i keep running into those.) Then the horrible black smoke turned white/grey and the heat went away. The burner is still running, just no heat. This is a very old burner, so I'm sure the coils need cleaned. I've been told that I need to let a prof. take it apart, and pressure wash the coils. If so, should that cure it? How much should this cost? Are there other things I should try first? Thanks, Jeremiah