23
CONTROLLER DETAILS
DELAYED “OFF” TIMERS
1. The Controller utilizes a Fan Purge any time it switches from an Active Mode to Standby. Fan Purge is the time period in which
the Outdoor Fan output (ODF1), is kept on 10 seconds more after all of the other heat pump outputs are turned off. Fan Purge
helps with pressure equalization and helping to limit frost build up on the outdoor coil.
2. When switching from any mode that has the Booster Compressor running to any mode that does not, including Standby, the
Controller shall implement a Cool Down period. In Cool Down, the Booster Compressor shall be turned off first and allow the
rest of the heat pump to run for 30 seconds before turning off the rest of the outputs. This Cool Down period accelerates the
sump equalization between the compressors and helps eliminate the pressure differential between the low and the high sides
of the system.
3. Other than the required on-to-off staging that is described above, the other outputs are switched off all at the same time. As
described in the fault section, during certain fault conditions, the on-to-off staging might be ignored.
COMPRESSOR PROTECTION FUNCTIONS
The following are the compressor protection functions that are implemented by the Controller:
Anti-Short Cycle Protection:
The short cycle protection period known as an Anti-Short Cycle, is required to protect the compressors from high head pressure
that could damage the compressors. Anti-Short Cycle is also implemented to protect the compressors against power frequency
faults and voltage faults. At the end of the Anti-Short Cycle, if the fault still exists, another Anti-Short Cycle is initiated and the
process continues as such. The details of the fault initiated Anti-Short Cycle is presented in the faults section.
The Anti-Short Cycle shall be implemented under the following circumstances:
o After power up.
o If a Demand Call (Y1/Y2) is lost from the thermostat.
o If the 24VAC voltage drops below 16V R.M.S. while the Controller is in a Heat Mode, Defrost Mode or Cool Mode, and the
microcontroller on the Controller does not reset.
o In the presence of Abnormal Frequency Fault, No Line Frequency Fault, Over Voltage or Under Voltage Fault.
(NOTE) If the voltage drop or power loss occurs while the Controller is in Defrost Mode 1 or 2, the Controller shall initiate the
Sacrificial Defrost after the Anti-Short Cycle. If the power loss occurs while the Controller is in Defrost Mode 3, the Controller
shall reset the timers and continue normal operation after the Anti-Short Cycle. The same strategy is implemented if the heat
pump outputs are shut down due to a fault condition.
During a 3 minute Anti-Short Cycle, the Controller shuts down all the outputs and the RV in Cool mode only.
1 Cylinder to 2 Cylinders Primary Compressor Protection:
When there is a shift from the 1 Cylinder to 2 Cylinders of the Primary Compressor, the Controller will implement a 2-minute
time delay between deactivating 1 Cylinder and activating 2 Cylinders. During this time, the indoor air handler unit fan and the
Acadia outdoor unit fan will stay energized.
(Note) During Heat Mode or Cool Mode, once the Primary Compressor is transitioned to 2 Cylinders operation, it should NEVER
transition back to 1 Cylinder operation until the heating or cooling call has ended, and at minimum, the Controller runs an Anti-
Short Cycle.
Minimum runtime protection:
Compressors energizing MUST run for a minimum of 2 minutes unless one of the following faults occur: High or low pressure,
over or under current, no current, a line temperature fault, 24VAC short, over or under voltage, or a fuse blows.
To Next Page
Loading...