23
P/N 032498h
Step 5: Set the SMC55-HWQS Advanced Parameters to Modify the
Functionality of the HVAC System
(continued)
Parameters Applicable to All Types of HVAC Equipment
(continued)
(26A) Cannot Reach Setpoint Timeout
Use this parameter to identify the maximum time it should take to reach the desired setpoint. If the desired setpoint is not
reached within this time then an alarm is triggered to notify the user.
(27A) Cannot Reach Setpoint Action
Use this parameter to identify whether or not the system should continue heating or cooling after the alarm for ‘Cannot Reach
Setpoint’ is triggered.
Set this parameter to ‘00’ if the system should continue heating/cooling. Set this parameter to ‘01’ if the system should stop
heating or cooling when ‘Cannot Reach Setpoint’ alarm is triggered.
Parameters Applicable to Conventional and Heat Pump Systems
This section lists out the details of the advanced configuration parameters applicable to Conventional and Heat Pump systems.
(70A) Minimum Compressor Run Time (MCRT)
Use this parameter to identify the minimum time the compressor must run to ensure proper lubrication. Refer to
Figure 8
below.
Even though the desired temperature setpoint is met the compressor will run for an additional amount of time till the minimum
compressor run time expires.
(71A) Minimum Compressor Off Time (MCOT)
Use this parameter to identify the minimum time for which the compressor must remain Off before it can start. This delay is
intended to reduce compressor restart stress. Fan will stay off in Auto mode during this delay. Refer to the
Figure 9
below, the
compressor will start only after MCOT has expired.
Continued on next page...
Figure 8: Compressor Runs Until Minimum Compressor Time Expires
Figure 9: Minimum Time for Which The Compressor Must Remain Off Before It Can Start
Min Compressor Run Time
Call Input for Compressor
Y
1
- Compressor
signal out
MCRT = 1 minute
MCRT = 1 minute
Call for no
compressor
Call for no
compressor
MCRT Starts
MCRT Starts
Time
Min Compressor Off Time
Call Input for Compressor
Y
1
- Compressor
signal out
G - Fan output signal
Call for no compressor,
MCOT Start
Call for no compressor,
MCOT Start
MCOT = 5 minute
MCOT = 5 minute
Time