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18. MAGNUM Condenser Control Strategy
Modulating Step Common - This type of condenser has a common fan bank for the system. The control will
be on the systems highest discharge pressure. The Relay Outputs are also supported along with an Analog
Output
When the unit is in cooling only mode the condenser control is as described in the set points below.
When the unit is in heating only mode the control is as described below with the exception that Set Point 163
(‘CondHtOffst’) is added to Set Point 50 (‘CND TRGT’).
49 CND START %
(Modulating Type)
If active, then the value is the starting % for the AO when the RO that is tied to it turns on.
The value in the “Time (SEC)” cell is the AO starting stage. If no Relays are used when
CMP starts set value.
50 CND TRGT
(Modulating Type)
Target the logic will try to maintain by modulating the AO.
51 CND ADJ DIV
(Modulating Type)
Controls scaling of the amount the AO is adjusted (usually 1). The larger the number the
smaller the AO adjustment as the adjustment will be divided by this value.
CND VFD MIN If there is a VFD associated with the condenser, this is the starting minimum speed.
‘Time (sec)’ fi eld: This fi eld contains the condenser stage that must be on before the VFD
is modulated.
52 CND MIN %
(Modulating Type)
Minimum AO % allowed.
If compressor is off, then check the “Time (SEC)” fi eld:
If 0, then the AO % will be set to the value of this setpoint. If 2 and the run/stop is set to
run, then set the AO % to 100%, else set the AO % to 0%. This option is selected in the
“Default Valve Opening % when Comp. is OFF” box in the condenser information section
in the MAG HVAC screen.
53 CND ROC-
(Modulating Type)
Maximum negative rate of change allowed. If the rate of change is less than this setpoint,
then stop modulating the AO. The absolute value of this setpoint also serves as the
maximum positive rate of change allowed. If the rate of change is greater than the
absolute value of this setpoint, then stop modulating the AO.
54 CND ADJ MULT
(Modulating Type)
Controls scaling of the amount the AO is adjusted. The larger the number the larger the
AO adjustment as the adjustment will be multiplied by this value.
55 CND MIN ADJ
(Modulating Type)
The value in this setpoint is the minimum % the AO will be modulated when a change is
made.
163 CondHtOffst This value will be added to the target pressure discharge pressure target during heating
mode.
When the system is in SHC (Simultaneous Heating and Cooling), the condenser fan is not used.
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