Condensate drain for horizontal installations

What is going on

Horizontal installs are left-side drain only, and the trap has to move outside the cabinet. Auxiliary drain pan goes under any horizontal evaporator or 95% furnace.

Likely causes

• Furnace being installed on its side
• Trap still inside the cabinet from the upflow setup
• Inducer hose on the wrong drain tap
• Drain connected to a closed line that backs up
• No auxiliary drain pan under the coil

Check in this order

1. Install an auxiliary drain pan under any horizontal evaporator or 95% furnace, connected to a separate drain line with no trap, because a trap would block the overflow.
2. Move the trap to the outside of the cabinet through the long circular hole, next to the secondary cell.
3. Trim the larger drain line from the secondary cell to fit to the new trap location.
4. On upflow units, plug the blower deck hole the tube went through and extend the inducer drain tube with the supplied tubing if needed.
5. Move the inducer hose to the other drain tap, 90 degrees clockwise, and move the cap to the unused tap.
6. Connect drains only to an open or vented drain.
7. Pour water into the trap and confirm it drains with no leaks.

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)