Controls and Sequence of Operation
Sequence of Operation
The Ice Bear unit is thermostatically controlled in the same manner as a conventional DX system. The
controller for the Ice Bear unit regulates the refrigerant and the unit’s internal components similarly to a
conventional DX air conditioning system. When a packaged unit is equipped with an economizer, the
economizer and the HVAC system will operate normally in collaboration with the Ice Bear unit.
The Ice Bear unit’s programmable controller responds to a single- or two-stage thermostat input. Either
configuration allows the Ice Bear unit to control the base system (allowing DX cooling during Ice Make,
for example). With a two-stage input, the Ice Bear unit and the additional system may be set up to
provide cooling simultaneously; whereas, with a single-stage input, only one system will provide cooling
at any given time. A single stage DX system connected to an Ice Bear unit is referred to as the backup
system. In a two-stage DX system with matching thermostat, the second DX system is referred to as a
parallel system. The programming for the Ice Bear unit’s internal controller is based on the desired Ice
Make and Ice Cooling operations. The Ice Bear unit can be configured to provide Ice Cooling for any
period of time consistent with the maximum cooling capacity, tank charge capacity, and tank recharge
requirements. The desired operating schedules are set prior to shipment or by a certified installer in the
field and can, if required, be reprogrammed remotely for optimization purposes.
The Ice Bear unit integrates with facility control systems and simple thermostats through traditional
24VAC signals, both for control and status feedback. No other communications to a facility management
system are required. The Ice Bear unit is unique as an energy storage device in that it is a fully packaged,
self-contained system. As such, it optimizes its performance independently of a facility management
system. Integration for Supervisory Control and Data Access (SCADA), additional monitoring, and other
advanced features are viable, but are not part of the standard offering.
For California Title 24 compliance applications, the programming is unalterable and operates within the
parameters of the specified product model. Control parameters are given at the factory.
Charging (Ice Make Mode)
Startup Sequence
1.
Fan #1 starts and the Electronic Expansion Valve (EEV) is reset. (Charging LED blinks once.)
2.
There is a 4 second delay.
3.
Fan #2 starts.
4.
Initial EEV position is set.
5.
There is a 26 second delay.
6.
Superheat set point is derived from the Condenser liquid temperature.
7.
Compressor starts. (Charging LED blinks 3 times).
8.
There is a 10 second delay.
9.
EEV will start to control the system. (Charging LED is on solid.)
Full Charge Cutoff Sequence
1.
Upon reaching charge cutoff pressure (typically 98.5 psia), the charging operation shuts down after
5 minutes.
2.
The EEV is set to the closed position.
Ice Bear
®
30 Unit Application Guide
15