month I would like to discuss air conditioner condensate
drains. I seem to see much confusion regarding drain configuration
a condensate drain is not required to be trapped by any
of the Codes. Most manufacturers of air conditioning components
require a trap on the primary condensate line to keep conditioned
air in the air handler and to prevent insects from entering
the air handler through the condensate line. A vent (some
manufacturers call it a clean out) is usually required on
the outlet side of the trap (install on the air handler
side would negate the purpose of the trap) by the manufacturer.
Most new models have a sticker on the air handler at the
drain tapping showing proper drain configuration.
of the time condensate is gravity drained (meaning sloped
to drain its entire length) to the exterior grade by a PVC
or other pipe. The termination is usually visible, but not
required to be visible. The secondary, or emergency drain,
should be visible to alert the occupants of a problem. Since
most layperson occupants have no idea water flowing from
this secondary drain indicates a problem, many technicians
are now installing a float switch in the drain pan and/or
secondary line to shut down the system in the event of a
primary condensate drain malfunction. A non-working system
usually promotes a phone call to the service company instead
of the usual ignoring the water flowing from the secondary.
jurisdictions have provisions for alternate methods of condensate
disposal besides just draining to exterior grade or a floor
drain. Any connection to the sanitary sewer system will
require a trap. This is called an indirect waste by the
Codes. Many times I see condensate drains terminating at
trapped receptors (a standpipe, like used for the clothes
washer) connected to the sanitary sewer system. Traps installed
only for the condensate drain will require trap primers
to keep them wet. Because of this problem the most common
termination locations are routinely wetted traps such as
lavatory sinks and bathtubs. The fixture keeps the trap
wet to prevent sewer gas flow back into the air handler.
The condensate is connected with a branch tailpiece on the
fixture side of the trap, such as to the outlet of the lavatory
sink or the overflow of the bathtub. Connection to the sewer
side of the trap is improper and will result in sewer gas
flow to the air handler since the condensate line trap (if
installed) will dry out in winter. Another common location
for condensate disposal is the clothes washer standpipe.
pumps are commonly used where gravity drain is not possible.
These pumps accept the condensate and pump the liquid to
an approved location once the tank is filled to a predetermined
level. The outlet pipe from the pump is not required to
be trapped. The inlet from the air handler should be installed
per the manufacturer recommendations, which could be trapped
this clears up some questions about condensate.
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