Rheem 96MDV Series, Installation Instructions Manual

Page: 67 / 128

67
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CONDENSATE DRAIN
CONDENSATE DRAIN & DRAIN NEUTRALIZER
GENERAL INFORMATION
IMPORTANT: Do not connect into a common drain line with
an air conditioner evaporator coil drain located below the fur-
nace. A blocked or restricted drain line can result in over-
flow of the coil pan and negate the furnace blocked drain
shutoff control.
The condensate drain trap is self-priming. Upon the first
heat attempt after installation or the first ignition after a long
off period (e.g. summer), the trap will be dry allowing air to
pull through the trap and causing the condensate to be held
in the collector box by the negative pressure while the in-
ducer is energized.
Condensate builds up in the collector box until the level
reaches the electronic water level sensor. When this hap-
pens the heat attempt is ended thus shutting off the inducer
after a post purge. This relieves the negative pressure
pulled through the trap and the water then falls into the trap
generally priming it after the first time. Note that in some cir-
cumstances this process may be repeated up to four times
before the trap is fully primed – particularly in horizontal in-
stallations where there is less volume of water in the collec-
tor box below the water level sensor.
Important: There are two options when choosing a height
for the condensate vent riser (also see Figure 35):
A. CONDENSATE OVERFLOW – When the top of the vent
tube is below the elevation of the LOWER condensate water
level sensor (aka electronic water level sensor) the furnace
will continue to run even if the drain is blocked. A blocked
drain will cause the condensate water to overflow the vent
and spill water on the floor below it but the furnace will con-
tinue to run and heat will be provided. If the installer uses
this approach, he must make sure that there is a mechanism
for handling the possibility of water overflow onto the floor in
the event of a blocked drain.
B. FURNACE SHUTOFF – When the top of the vent tube is
above the elevation of the LOWER condensate water level
sensor (aka electronic water level sensor), the furnace will
be shut off in the event of a blocked drain and no heat will
be provided.
NOTE: IT IS IMPORTANT ANY TIME THE FURNACE IS IN-
STALLED IN AN ENVIRONMENT WHERE THE TEMPER-
ATURE CAN GET BELOW FREEZING THAT THE TRAP
AND ALL CONDENSATE LINE BE PROTECTED FROM
FREEZING. IF THE FURNACE IS EXPOSED TO TEM-
PERATURES BELOW FREEZING, THE TRAP WILL
FREEZE AND THIS WILL CAUSE THE FURNACE TO
SHUT DOWN AND/OR DAMAGE THE DRAIN TRAP UN-
LESS FREEZE PROTECTION IS INSTALLED.
If local codes require, install a condensate neutralizer car-
tridge in the drain line. Install cartridge in horizontal position
only. Also install an overflow line if routing to a floor drain.
See Figure 35.
If no floor drain is available, install a condensate pump that
is resistant to acidic water. Pumps are available from your
local distributor. If pump used is not resistant to acidic water,
a condensate neutralizer must be used ahead of the pump.
The condensate pump must have an auxiliary safety switch
to prevent operation of the furnace and resulting overflow of
condensate in the event of pump failure. The safety switch
must be wired through the “R” circuit only (low voltage) to
provide operation in either heating or cooling modes.
For Econet-enabled systems, the condensate overflow
switch can be connected to the auxiliary inputs on the fur-
nace control – see section titled “Auxiliary Inputs” in the fur-
nace control section.
!
CAUTION
DO NOT RUN DRAIN OUTDOORS. FREEZING OF
CONDENSATE CAN CAUSE PROPERTY DAMAGE.