Vent/flue pipe sizing and elbow rules (non-direct vent)

What is going on

Rules for building the vent/flue run on a non-direct vent install. The length table itself did not come through legibly on these pages, so take the maximum lengths from the manual's vent table before cutting pipe.

Check in this order

1. At 7,000 ft altitude or higher, use 3 in venting.
2. Keep each vent pipe at least 5 ft long with at least one elbow or tee.
3. 2 1/2 in or 3 in pipe may replace 2 in pipe.
4. Count the tee in the vent termination when counting elbows in the run.
5. Count two 45 degree long sweep elbows as one 90 degree elbow.
6. Secure one 90 degree elbow on the combustion air intake to prevent blockage.
7. Limits apply to each pipe individually (inlet or flue), not as a combined total.
8. Any 90 or 45 degree elbow used for termination must point down.

More furnace guides

• Airflow lower than demanded, furnace runs on low stage when high stage is expected
• Alternate combustion air opening (upflow or horizontal)
• Alternate vent/flue location (upflow or horizontal left)
• Annual inspection checklist
• Auxiliary limit control (location and purpose)
• Auxiliary limit switch open (blower compartment)