Goodman Furnace: Vent/flue pipe sizing and elbow rules (non-direct vent)
Vent/flue pipe sizing and elbow rules (non-direct vent) on a Goodman furnace: 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.
Applies to: Non-direct vent installations
How to fix vent/flue pipe sizing and elbow rules (non-direct vent): step by step
- At 7,000 ft altitude or higher, use 3 in venting.
- Keep each vent pipe at least 5 ft long with at least one elbow or tee.
- 2 1/2 in or 3 in pipe may replace 2 in pipe.
- Count the tee in the vent termination when counting elbows in the run.
- Count two 45 degree long sweep elbows as one 90 degree elbow.
- Secure one 90 degree elbow on the combustion air intake to prevent blockage.
- Limits apply to each pipe individually (inlet or flue), not as a combined total.
- Any 90 or 45 degree elbow used for termination must point down.
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 service manual, p. 16. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.