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Horizontal Furnace - Code 3 - Drain Trap

Article ID: 22
Last updated: 13 Apr, 2017

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.
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Article ID: 22
Last updated: 13 Apr, 2017
Revision: 3
Views: 110
Comments: 0
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