Horizontal Furnace - Code 3 - Drain Trap

Make:  York

Model or Series:  TG9S

Type:  90% Furnace, Horizontal

Problem Description:  Code 3 Pressure Switch Lockouts

Observed Symptoms:  Furnace runs for a while then locks out.

Solution:  Installed tee and air vent in rubber drain hose inside the furnace cabinet.

Additional Information:  Furnace drain had a trap in the 3/4" pvc immediately after leaving the furnace cabinet.

• The furnace drain is internally trapped.
• Install instructions require an air vent in the drain immediately after leaving the furnace cabinet.
• In this application it was not possible to get an air vent in the pvc drain before the trap.