PUMP OUT
The pump out function is a standard feature on the 25 to 50 ton systems. The pump out circuit is activated each time the first and third compressor stage is called for by the thermo- stat. As such, it’s a “Pump Out On Start Up” design. A nor- mally closed solenoid valve (POS1, 2, 3 or 4) is placed in the liquid line, just prior to expansion valve.
When cooling is not being called for by the thermostat, the pump out solenoid (POS) is not energized, so it’s in the closed position. When the Simplicity™ control receives a call for cooling, it energizes a compressor. With the POS being closed, it causes the pressure on the low side of the system to begin falling.
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When the low pressure switch (LPS) opens, the control board energizes its
If the low pressure switch is already open on a call for cool- ing, the pump out relay is energized immediately. If the LPS does not open after 5 minutes, the pump out relay is ener- gized.
BEARING ALIGNMENT: LB600
Before the supply air blower drive is installed, turn the blower assembly by hand several times. If it doesn't rotate freely, the center bearing may have been knocked out of alignment dur- ing shipping and/or rigging. To realign, refer to 15 and the fol- lowing instructions:
1.Loosen the bearing collar set screw.
2.With a drift pin in the bearing collar removal hole, loosen the bearing collar by tapping the drift pin in the direction opposite to the shaft rotation.
3.Loosen bolts "A" and "B".
4.Remove the shim.
NOTE: The bearing support angle must be horizontal to the unit and below the bearing.
5.Tighten bolts "B" without the shim.
6.Tighten bolts "A".
7.With a drift pin in the bearing collar removal hole, tighten the bearing collar by tapping the drift pin once in the direction of the shaft rotation.
8.Tighten the bearing collar set screw.
9.Loosen bolts "B"
10.Raise the blower shaft and
FIGURE 15 - LB600 CENTER BEARING
AIR SYSTEM ADJUSTMENT
Refer to Tables
TWIN BELT DRIVE ADJUSTMENT
Check to see if both belts drive at the same speed. Do this by making a mark across both belts. Turn the drive several revolutions by hand. If mark has not separated, the belts are traveling at the same speed.
Twin groove blower motor pulleys should be installed with the shaft set screw (A) towards the motor (see 16).
BB
A
E
D
C
C
STATIONARY WEB
FIGURE 16 - DOUBLE GROOVE PULLEY
If necessary to align pulleys, the housing of the twin groove motor pulley may extend 25% of its length beyond end of motor shaft.
Always align twin groove pulleys using the stationary web.
The blower motor pulleys are adjustable by half turns. Select required RPM from table 5 and adjust pulley.
11. Tighten bolts "B".
18 | Unitary Products Group |