Condensate drain for vertical upflow and downflow installations

What is going on

Upflow and downflow units use different drain tubing and trap routing, and the drain should have a drain pan under it.

Check in this order

1. Install a drain pan under the furnace to prevent leak damage.
2. Upflow find the drain tubing for left and right side drainage in the blower compartment. Run it from the trap to the side of the unit, and trim excess to avoid kinks.
3. Upflow use the 2 in to 3 in reducing coupling marked TOP, with the TOP mark on the top side of the pipe and the straight side on the bottom.
4. Downflow seal the fitting to the trap with RTV silicone so the trap can be removed for cleaning.
5. Downflow left side use a 1/2 in slip PVC fitting.
6. Downflow right side remove the drain lines, rotate the trap 180 degrees, and reconnect. Use a 1/2 in 90 degree CPVC street elbow sealed with RTV, 1/2 in CPVC to an elbow, then 1/2 in CPVC out through the right side knockout.

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)