NOTE: To minimize the possibility of system failure due to dirt and moisture, a
The temperature required to make or break a brazed joint is sufficiently high to cause oxidation of the copper unless an inert atmosphere is provide.
CAUTION: Dry nitrogen should flow through a brazed joint at all times when heat is being applied and until the joint has cooled.
The liquid, suction and drain connections inside the unit must be piped to the outside. Refer to Unit Dimensions for loca- tions of the access openings in the unit panel.
Protective grommets are supplied by the factory for field placement into these access openings.
The blower units are shipped with the coil section side pan- els suitable for right hand piping connections when viewed from the return air side of the unit.
The refrigerant piping and the condensate drain connection may be routed through either side of the unit.
If left hand piping is required, the two panels on the right side of the coil section can be interchanged with the single panel on the left hand side of the coil section.
When left hand piping connections are installed, the suction line must be insulated to prevent moisture from condensing and being carried into the blower section.
EXPANSION VALVE BULB
The expansion valve bulb must be fastened in a 4 o'clock po- sition to the suction line outside the cabinet after the piping connections have been made. Use the clamps supplied with the valve.
DRAIN CONNECTION
The drain line MUST be trapped because the coil is located on the negative side of the supply air blower. It must also be protected from freezing temperatures.
A
78" (22.2mm) OD stub connection is provided within the cabinet on both ends of the condensate drain pan for either
(76)
(50)
FIG 3 - RECOMMENDED DRAIN PIPING
left hand or right hand piping connections. Refer to Figure 3 for recommended drain piping.
The drain line is usually located on the same end of the coil section as the refrigerant connections. The line should be in- sulated where moisture drippage will be objectionable or cause damage to the area. Seal the unused drain connec- tion with a suitable mastic.
The 3" (76mm) dimension must equal or exceed the nega- tive static pressure developed by the supply air blower. If it does not, condensate will not drain properly and may over- flow the drain pan. The trap must be at least 2" (50mm) deep to maintain a water seal under all operating conditions, espe- cially during blower
SUPPLY AIR BLOWER ADJUSTMENT
The RPM of the supply air blower will depend on the re- quired airflow, the unit accessories and the static resistances of both the supply and the return air duct systems. With this information, the RPM for the supply air blower can be deter- mined from the blower performance in Table 5
Knowing the required blower RPM and the blower motor HP, the setting (turns open) for the supply air motor pulley can be determined from Table 3..
TABLE 3 - SUPPLY AIR BLOWER MOTOR PULLEY ADJUSTMENT
TURNS OPEN* | BLOWER DRIVE RANGE (RPM) | |
| ||
5 | 615 | |
4 | 652 | |
3 | 689 | |
2 | 726 | |
1 | 763 | |
0 | 800 |
* Pulleys can be adjusted in
Each motor pulley has:
1.A threaded barrel with two flats (or notched recesses) 180 degrees apart.
2.A movable flange with one set screw.
After the movable flange has been rotated to the proper number of “turns open”, the set screw should be tightened against the flat on the barrel to lock the movable flange in place. If the pulley includes a locking collar, the locking collar must be loosened to adjust the setting of the movable flange.
Note the following:
1.The supply airflow must be within the limitations shown in Table 2.
2.All pulleys can be adjusted in
3.The tension on the belt should be adjusted for a deflection
of 316
" (5mm) per foot (305mm) of belt span with an applied force of approximately 3 lbs (1.4kg). This adjustment is made by moving the blower motor mounting plate. Refer to Figure 4. Turning the adjustment bolt (B) moves the motor mounting plate up or down. Note - Never loosen the two nuts (C). Four hex nuts (A) have to be loosed to move the mounting plate and retightened after the mounting plate has been moved to the proper position.
4 | Unitary Products Group |
