www.whisperkool.com | Page 17
DRAIN LINE PUMP SYSTEM
1. Drain pan fills with water which flows into reservoir. Intake hose between reservoir and pump is empty (filled with
air).
2. Raising water lifts float, activating pump, which self primes by drawing water up from reservoir. During this period
the pump is operating hot and dry and will click loudly. Once the air in the intake hose has been purged, water
entering the pump cools and lubricates it so that the clicking noise becomes a low hum. Water flows through the
pump and out of the discharge hose.
3. Water level in the reservoir has now receded enough to lower the float, deactivating the pump. However, the
weight of the water in the discharge hose plus atmospheric pressure at the drain pan outlet forces the water
remaining in the intake hose to continue flowing out through the pump until the reservoir, intake hose, pump and
discharge hose are completely empty, at which point the siphoning stops.
4. As the evaporator produces more condensate, the drain pan again fills up with water which flows into the reservoir.
Since the intake hose is filled with air again, the cycle repeats itself.
RESULT: EVERY TIME THE PUMP
RUNS HOT AND DRY, IT SUSTAINS
A SMALL AMOUNT OF DAMAGE
WHICH CAUSES PREMATURE WEAR.
THE NEXT TIME THE PUMP STARTS
UP DRY, IT MAY RUN FOR 11
SECONDS BEFORE IT COOLS DOWN
THE NEXT TIME 12 SECONDS
AND SO ON. ALSO WHILE THIS IS
OCCURRING, THE PUMP IS CLICKING
LOUDLY. THIS IS ACCEPTABLE
DURING THE INITIAL START UP
PHASE, BUT NOT ACCEPTABLE
DURING SUBSEQUENT OPERATIONS
OF THE PUMP.
WHEN YOU CONSIDER THAT
THIS WILL OCCUR A NUMBER
OF TIMES EVERY DAY OF THE
COOLING SEASON IT IS EASY
TO SEE THAT THE DAMAGE WILL
RAPIDLY ACCUMULATE. IF THE
PUMP IS ALLOWED OPERATE IN
THIS CONDITION REPEATEDLY, THE
NOISY PERIOD WILL GET LONGER
AND LONGER OVER THE COOLING
SEASON UNTIL THE CUSTOMER
COMPLAINS OR THE PUMP
EVENTUALLY FAILS.
THIS CAN EASILY BE AVOIDED
BY INSTALLING THE DISCHARGE
HOSING CORRECTLY WITH AN
ANTI-SIPHON DEVICE WHICH WILL
EQUALIZE THE ATMOSPHERIC
PRESSURE AND ELIMINATE THE
SIPHONING.
INCORRECT:
Failure to follow correct Discharge Hose installation will damage pump.
4
3
1
2
DRAIN PAN
DRAIN PAN
DRAIN PAN
DRAIN PAN
PUMP
PUMP
PUMP
PUMP
BREATHER TUBE
BREATHER TUBE
BREATHER TUBE
BREATHER TUBE
RESERVOIR
RESERVOIR
RESERVOIR
RESERVOIR
ATMOSPHERE
PRESSURE
