Jeremias Boot Tee has low Resistance
Our Boot Tee has a 4" gore on the narrow side to deflect flue gases towards the termination.
The resistance is the same as a 45-degree elbow and lateral tee. Other Boot Tees allow all the flue gases to hit the back wall at 90-degrees making them the same resistance as a 90-degree tee.
Jeremias Boot Tees are better by design.