Bryant 580J*08--14D, F appendix Condenser Coil Service, RTU-MP Control System

CONDENSER COIL SERVICE

Condenser Coil

The condenser coil is new NOVATION Heat Exchanger Technology. This is an all-aluminum construction with louvered fins over single-depth crosstubes. The crosstubes have multiple small passages through which the refrigerant passes from header to header on each end. Tubes and fins are both aluminum construction. Connection tube joints are copper. The coil may be one-row or two-row. Two-row coils are spaced apart to assist in cleaning.

Repairing NOVATION Condenser Tube Leaks

RCD offers service repair kit Part Number 50TJ660007 for repairing tube leaks in the NOVATION coil crosstubes. This kit includes approved braze materials (aluminum flux core braze rods), a heat shield, a stainless steel brush, replacement fin segments, adhesive for replacing fin segments, and instructions specific to the NOVATION aluminum coil. See EPIC for instruction sheet 99TA526379.

The repair procedure requires the use of MAPP gas and torch (must be supplied by servicer) instead of conventional oxyacetylene fuel and torch. While the flame temperature for MAPP is lower than that of oxyacetylene (and thus provides more flexibility when working on aluminum), the flame temperature is still higher than the melting temperature of aluminum, so user caution is required. Follow instructions carefully. Use the heat shield.

Replacing NOVATION Condenser Coil

The service replacement coil is preformed and is equipped with transition joints with copper stub tubes. When brazing the connection joints to the unit tubing, use a wet cloth around the aluminum tube at the transition joint. Avoid applying torch flame directly onto the aluminum tubing.

RTU-MP CONTROL SYSTEM

The RTU-MP controller provides expanded stand-alone operation of the HVAC system plus connection and control through communication with several Building Automation Systems (BAS) through popular third-party network systems. (See Fig. 42.) The available network systems are BACnet MP/TP, Modbus and Johnson J2. Communication with LonWorks is also possible by adding an accessory interface card to the RTU-MP. Selection of the communication protocol and baud rate are made at on-board DIP switches.

Bryant’s diagnostic display tools BACviewer6 Handheld and Virtual BACview (loaded on a portable PC) must be used with the RTU-MP controller. Connection to the RTU-MP board is at the J12 access port. (See Fig. 42.)

The RTU-MP control is factory-mounted in the 48TC unit’s main control box, to the left of the LCTB. (See Fig. 43.) Factory wiring is completed through harnesses connected to the LCTB. Field connections for RTU-MP sensors will be made at the Phoenix connectors on the RTU-MP board. The factory-installed RTU-MP control includes the supply-air temperature (SAT) sensor. The outdoor air temperature (OAT) sensor is included in the FIOP/accessory EconoMi$er 2 package.

Refer to Table 15, RTU-MP Controller Inputs and Outputs, for locations of all connections to the RTU-MP board.

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