Corrosion in secondary drain pan. Found during a Phoenix Home Inspection

Secondary Condensate Drainage

by Southwest Premier on March 5, 2010

DEFECT: Secondary Condensate Drainage

The air conditioner or heat pump in your home produces allot of condensation on the evaporator coils when it is running, this is totally normal and expected.  This condensation has to be drained away through an appropriate drain to prevent moisture damage from a constant drip, depending on the environment a surprising amount of moisture needs to be drained away.

The normal method of drainage is the primary drain pan which is typically an integral part of the air conditioner unit.  This pan sits under the coil, collects the condensation and directs it to a drain line so it can be safely drained.

On split air conditioner or heat pump systems with the compressor unit outside and the air handler inside a secondary method of drainage is required to prevent water damage should the primary drain clog, fail or be inadequate to drain away the water.  The normal method of doing this is to install a secondary drain pan with a separate drain line under the air handler unit.

Found during a Phoenix AZ Home Inspection, corrosion in secondary condensate drain pan

Corrosion in Secondary Drain pan

Leakage from secondary condensate drain found during a Phoenix AZ Home Inspection

Secondary condensate drain leakage

If the primary drain should fail and the integral pan overflows, it leaks out of the unit and into the secondary drain pan where it can be safely drained away.  The location of the secondary drain line outlet should be located in a conspicuous location so you will know if it is draining.  Anytime you see water leaking out of the secondary drain you know you have a problem with the primary drain.

These problems usually require a little investigation by a qualified HVAC contractor to determine the exact cause.  Typical problems can include:

  • Air handler not level or tilting away from the drain
  • Improperly installed drain trap on primary drain line
  • Leak in primary drain pan
  • Clog or obstruction in primary drain line

If left un-repaired the constant moisture can corrode the air handler metal case and secondary drain pan causing leakage into the attic or onto the drywall causing water damage to the home.  Another good indication that there is water draining into the secondary condensate drain pan is a rust streak down the side of the home or on the ground by the secondary condensate drain line outlet.

If you see water draining out of your secondary condensate drain line, call a qualified HVAC contractor and get it fixed right away.


This information was provided courtesy of Southwest Premier Home Inspection, LLC.  Reproduction in any form is not permitted without consent.  Copyright 2008-2010 Southwest Premier Home Inspection, LLC.

Southwest Premier Home Inspection is the Phoenix Arizona Home Inspection leader.  To find out more  visit our Phoenix Home Inspection website www.swpHomeInspect.com

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