Download Section on Condensate Drainage

1. Check to see that CONDENSATE DRAIN IS FUNCTIONING and that the
CONDENSATE IS DISPOSED OF PROPERLY ACCORDING TO LOCAL, STATE,
AND NATIONAL CODES. The RECOMMENDED METHOD, if not stated in the
manufacturer’s literature, is to DRAIN CONDENSATE INTO A NEUTRALIZING
DEVICE AND INTO THE EXISTING DRAINAGE / SEWER LINE.
The furnace must be set plumb in such a way as to facilitate condensate drainage.
Condensate must drain in such a way that it won’t pool in a basement or crawlspace. A field
installed neutralizer must be used when condensate is to be drained into a septic or sewer
system. Check with the local authority having jurisdiction to be sure.
PVC is the preferred drain line material. Use the same size pipe that’s on the unit connector
the entire length of the drain line. When you install the drain line, make sure to deburr the
inside of each joint connection. Clean, prime and glue each joint per manufacturers
instructions.
Do not prime and cement the drain trap. Some manufacturers design in an internal trap so be
sure to read the instructions regarding the condensate drainage trap. If the trap is external,
most manufacturers recommend using Teflon tape to get a water tight seal. Educate the
client on maintaining the drain trap.
Some manufacturers allow the tapping in of the furnace condensate drain line into the
existing AC coil drain line down stream from the AC trap as long as both are of the same
material. Do not tap into a drain line of an AC coil located on the bottom of the furnace
since clogging of the common drain line may cause the furnace condensate to drain back into
the drain pan of the AC coil resulting in corrosion and damage to the coil.
Some manufacturers recommend venting the drain line to a height higher than the top of
secondary heat exchanger.
When the drain line runs through locations with ambient temperatures below freezing use a
UL listed self regulated heat tape. Some manufacturers have heat tape kits of varying lengths
for use with their products. The self regulated tape must be rated at 3 watts per foot. Tapes
with higher watt ratings may melt the drain line.
It must be installed around the condensate drain line in the unconditioned space. The tape
must be installed as Per Manufacturers Instructions. Field practices have demonstrated that
the tape works best when attached to the bottom of the drain line. The tape and line must be
insulated with fiberglass or other heat resistant material.
2. If there is a CONDENSATE PUMP check to see that it is IN GOOD WORKING ORDER
AND PROPERLY INSTALLED.
The float in the pump must be suitable for use with acidic water. The installation instructions
will state if it is suitable for installation with condensing gas furnaces.
Use clear vinyl tubing. It must be installed without restrictions or crimping. It must be
firmly and permanently held in place situated so that it won’t get damaged.
The line voltage side of the condensate pump must be wired into a constant source of power
and not on a circuit with a switch. The safety switch should be wired on the “R or Red” side
of the low voltage circuit so that the pump will work on both heating and cooling modes if
the unit has a AC or heat pump added on.