Carrier 48MA/50ME016-040 specifications Ð Suggested Gas Piping 48MA, Ð Field Power Supply Details

*Shutoff valve not used except where required by code.

Properly cap any gas connection not being used.

Fig. 8 Ð Suggested Gas Piping (48MA)

Unit has factory-installed gas shutoff valves. Install gas shutoff valve external to unit if required by code (Fig. 8). After piping is complete, pressurize gas line and check for leaks with soap and water solution.

Do not use an open ¯ame when checking for gas leaks.

Optional Glycol Connections (50ME) Ð Each zone module has its own glycol heating coil and 115-v solenoid valve. Heating coils are connected in parallel to common sup- ply and return manifolds. Supply manifolds are equipped with bleed cocks. Supply and return connections are shown in Fig. 2 and 5. Unit does not have internal pressure relief for part-load operation. Maximum allowable system working pres- sure is 30 psig. Unit ratings are based on 20% glycol solu- tions. Install solution supply apparatus in accordance with application requirements, and mix glycol solution percent- age in accordance with glycol manufacturer's recommenda- tions. Freeze-up protection is not factory installed.

Field Power Supply Wiring Ð When installed, unit must be electrically grounded in accordance with local codes or, in the absence of local codes, with the National Electrical Code (NEC).

Unit has a circuit breaker for each compressor, each fan motor, and for each 50ME electric resistance heater assem- bly (if unit is so equipped). If required by local code, pro- vide an additional disconnect switch in accordance with code being followed.

All units have a main power supply terminal board in the power and condensing control box. The electric resistance heater power supply terminal board(s) (if unit is so equipped) on 50ME units is located in the heater control box at front of unit. See Fig. 2, 5, and 9.

All terminal boards are suitable for use with copper or aluminum wire.

Connect electrical conduit (a threaded pipe nipple) shipped with unit to threaded ®tting in roof curb and bottom of main power and condensing section control box. Route main power wires through conduit to terminal board in box as shown on unit label wiring diagram and in Fig. 9.

When installing 48MA,50ME040 units with optional 20-hp motor, the electrical conduit interconnecting the curb and con- trol box power wire openings will not accommodate alumi- num wire of the size that may be required. If aluminum wire cannot be accommodated, an external transition box and short lengths of no. 300 kcmil, 75 C copper wire from the tran- sition box to the unit main power connection are recommended.

Voltage to compressor terminals during compressor op- eration must be within voltage range indicated on unit name- plate. Phases must be balanced within 2%.

	LEGEND
EQUIP	Ð Equipment
GND	Ð Ground
TB	Ð Terminal Board

*208/230 v units only.

Fig. 9 Ð Field Power Supply Details

10