Take a look at the vent connector piping shown in Figures 1a, 1b and 1c. These photos were all taken at pellet boiler installations. Do you see something in common? What’s the issue and what can be done to resolve it?

Modern pellet-fueled boilers are sophisticated devices. Most of them have an internal draft-inducing blower. The speed of that blower is regulated based on the oxygen content of the flue gases. This allows the boiler to adjust the excess air supplied to the combustion chamber to maintain optimal combustion efficiency.