25
P/N 032498h
Step 5: Set the SMC55-HWQS Advanced Parameters to Modify the
Functionality of the HVAC System
(continued)
Parameters Applicable to Conventional and Heat Pump Systems
(continued)
(83A) Cool Stage 2
–
Off Delta
1
Use this parameter to identify the temperature below the cool setpoint when Cool Stage 2 should turn off. Refer to the control
diagrams in
Appendix A
. These diagrams graphically represent the Cool Stage 2-Off Delta for Conventional and Heat Pump
systems.
(84A) Compressor Cool Stage 2 Upstage Delay (CC2SUD)
1
Use this parameter to identify the time delay after the first stage of cooling has started before the Stage 2 for cooling starts. Refer to
Figure 10
below for the upstage delay before the Stage 2 of cooling is turned on.
(85A) Compressor Heat Stage 2 Upstage Delay (CH2SUD)
1
Use this parameter to identify the time delay after the first stage of heating has started before the Stage 2 of heating starts.
(88A) Reversing Valve Delay (RVD)
1
Applicable System:
Heat pump only.
Use this parameter to identify the time delay required for energizing the reversing valve. RVD is used to ensure that the reversing
valve is fully energized before turning on the compressor. This delay is used in the following scenarios:
a. Turning on the SMC55-HWQS.
b. Transitioning from heating to cooling and from cooling to heating (after MCOT expires).
c. Transitioning from operating mode ‘Off’ to operating mode ‘Heating’, ‘Cooling’, or ‘Auto’ (after MCOT expires).
Refer to
Figure 11
below, the system will start after both MCOT and RVD have expired.
Figure 10: Upstage Delay Before Starting Cooling Stage 2
Figure 11: The Heat Pump Starts Heating/Cooling Only After Reversing Valve Delay Expires
Call Input for Compressor
Energizing O/B valve - Enable
cooling
Y
1
- Compressor
signal out
Y
2
- Compressor
signal out
G - Fan On
Upstage 2nd cool
stage delay = 2 min.
Cooling energized
Call for Stage 2 cooling
FODC
OCFT
FODC
OCFT
Reversing Valve Delay
Call input for reversing valve
Call input for compressor
O/B - Reversing valve signal out
Y
1
- Compressor signal out
MCOT (5 min.)
Call for compressor
Call for compressor
MCOT started
MCOT started
RVD started
Reversing
Valve Delay
MCOT (5 min.)
1
Included with SMC55-HWQS version 7420 or newer, SMC55-RESI version 7302 or newer and HomeWorks Palladiom Thermostat version 1.10 or newer.
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