Horizontal vent termination through wall

What is going on

On a horizontal wall termination, the thing I find wrong most often is a vent set too close to grade. Snow drifts, mulch or a flower bed will bury it and the furnace trips on the pressure switch in the first cold snap. Vent and inlet terminals must clear the expected snow level, and the dimensions in the figures are what the manufacturer tested, so use them.

Likely causes

• Terminals too low and covered by snow or landscaping
• Exhaust and inlet too close, recirculating flue gas
• Insufficient overhang
• Elbow and tee spaced too far apart, upsetting the termination dimensions
• Wrong termination kit mixed with the figure dimensions

Check in this order

1. Locate the vent and inlet terminals at least 12 in above the normally expected snow level.
2. Maintain at least 12 in above the highest anticipated snow level or grade, whichever is higher.
3. Use at least 12 in of overhang for the termination (per figure).
4. Keep the exhaust and inlet ends separated by at least 9 in measured end to end (per figure).
5. Keep the elbow and tee as close together as possible.
6. Use 6 in minimum to 24 in maximum between the terminal and the adjacent fitting (per figure).
7. Termination kits BAYVENT200B or BAYAIR30AVENTA can replace the terminal options shown in the figures.
8. Walk around outside after install and check for obstructions.

More furnace guides

• Abnormal conditions and protection
• Adjust gas valve manifold pressure
• Air for combustion and ventilation in non-direct vent installs
• Airflow adjustment check
• Airflow and temperature rise check
• Bottom return filter rack installation (upflow)