The gent was using well water, and Nat gas seeped into the H2O https://thesoothingair.com/private-hous ... n-heating/.

I got the call because his relief valve popped, and the gas in the water lit off, and melted the overflow (plastic ) pipe.

Took a bi of anayzing from the experts to find that one..Only case like that I had, never heard of another.

Is he on well water?