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.
•
The electric expansion valve replaces a thermal 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.
•
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
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.
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