Specifications

9
Features
• One of the most energy-saving features of the Master Controller 2.0 Reverse Cycle Defrost system is free
floating head pressure. A head pressure control is not installed on Master Controller 2.0 systems. Without
this control, compressors work at the highest efficiency at the lowest possible condensing pressure rather
than at the limited pressure level typically found in conventional systems using a head pressure control valve
for low ambient environments. For more energy saving information, go to www.master-
bilt.com/pdfs/master_controller_vs_standard_system.pdf.
• Option for Mechanical Expansion Valve, or Electronic Expansion Valve
• With the electric expansion valve; the refrigerant flow of the electric expansion valve is modulated by the
true superheat, or the difference of evaporator outlet and evaporating temperatures.
• The room temperature sensor replaces the conventional temperature control. The temperature is set with
the pushbuttons on the Master Controller 2.0 board or through the web page. The default temperature must
be checked during the first startup of the machine against actual application temperature. Default must be
re-set to actual application temperature if there is a discrepancy.
• Evaporator Fans cycle during compressor off mode, and options for electric defrost heaters to cycle on-and-
off durring defrost for addition energy saving.
• The on-board timer is used for run time control and scheduling defrosts. No mechanical defrost timer is
necessary for this system. Once the power is turned on, the timer starts counting.
• The Master Controller 2.0 has the capability to perform scheduled defrost or demand defrost for either
Reverse Cycle hot gas defrost, or Electric defrost.
o When the scheduled defrost scheme is chosen, the on-board timer is used for scheduled defrosts.
The system works in the same fashion as a regular conventional system with mechanical defrost
timer.
o When the demand defrost is chosen, the controller will not initiate a defrost unless it is needed. The
low temperature system is pre-set with demand defrost.
• The demand defrost scheme is a pioneer design by Master-Bilt for freezer applications. Extensive lab tests
indicate that many unnecessary defrosts are eliminated and energy consumption reduced when using
demand defrost compared to using a conventional refrigeration system equipped with a mechanical defrost
timer.
• The operational status of modes, room temperature and alarms is displayed on the four-digit on-board
display.
• Manual defrost is available on standalone and Peer to Peer systems.
• All components are factory-mounted, pre-wired and tested to save on-site installation labor and reduce
chance of installation errors.
• The superheat set point has a wide adjustability range 5° to 20
o
F. This range allows the controller to meet
different customers’ needs, and require less refrigerant charge for winter operation than conventional
refrigeration unit when no head pressure valve is installed in the condensing unit.
• The controller can be used in low, medium and high temperature applications. The internal programming will
recognize the input of room temperature set point (RMSP) and automatically select appropriate segments of
the program for the application.
• The patented reverse cycle defrost control (United States Patent 7,073,344) reduces defrost energy usage
by up to 80% and decreases defrost time from 20-45 minutes (freezer equipped with electric heaters) to 3-5
minutes in a freezer or 1
1
/
2
– 2 minutes in a cooler with a completely clean defrost.
• Maximum operating suction pressure can be controlled by the electric expansion valve eliminating the
crankcase pressure regulator for some applications.
• Minimum operating suction pressure provides additional compressor protection.