Quote Originally Posted by jff6791 View Post
The previous photo was actually the old chimney - these pictures show the replacement. I'd agree with the flashing explanation if the stained area was confined to area down to roofline. It extends further out however suggesting a source from higher up. These are the numbers from boiler tune up a month ago:
Weil Mclain WTGO-7
Gross Stack Temp 460
Net Stack Temp 400
CO2 % 12
Smoke 0
Breech Draft .04
Overfire Draft .01
Efficiency 85%
Nozzle 200
Angle 60
Spray ES
From the height of that stack those stains are not coming from the gases at the the top.

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