Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
56
119 EcoOffsetON 10.0F
120 EconDelyFans 60s
121 EcoVlvMinVlv 0.0%
122 EcoVlvMaxVlv 100.0%
123 EcoVlvMaxAdj 5.0%
124 EcoVlvDelay 30s
125 EcoVlvMaxDly 120s
126 EcoVlv Mul 3
127 EcoVlv Div 2
Conditions when the run/stop was set to RUN
Ambient temperature 30.0F
Control temperature 48.5F
The ambient temperature is less than 44.0 (Setpoint #1) – 10.0 (Setpoint #119) and no mechanical cooling
steps are on; therefore, the Unit state will be ECONOMIZER ONLY and the economizer function will be
enabled.
The AO M-1 “3 WAY VLV” will be opened to its minimum valve of 0% (Setpoint #121) and it will be
modulated based upon the control temperature and the target (Setpoint #1). The first adjustment will be
48.5 – 44.0 = 4.5. This value will be adjusted by multiplier of 3 (Setpoint #126) and divided by 2 (Setpoint
#127) to give an adjusted value of 6.7. This value is blocked; maximum allowed adjustment, by Setpoint
#123 to allow an adjustment of 5.0%. The economizer valve opening will be increased by this amount if the
temperature control rate of change is greater than the value of Setpoint #27.
The economizer function will wait 30 seconds (Setpoint #124) before determining the next adjustment. If
the control temperature is now 47.3F; the following adjustment will be calculated.
47.3 – 44.0 = 3.3 x 3 / 2 = 4.9. Since this is less than 5.0 the valve will be open an additional 4.9% if the
temperature control rate of change is greater than the value of Setpoint #27.
Each adjustment will be made after a delay of 30 seconds. If the control temperature is below the control
target (Setpoint #1) and above the bottom the control zone (43.0F to 44.0F) there will be no change to
valve opening.
If the control temperature drops below the control zone the valve opening will be reduced. For example if
the control temperature is 42.6F then the following calculation will be made:
42.6 – 44.0 = 1.4 x 3 / 2 = 2.1. Since this is less than 5.0 the valve opening will be reduced an additional
2.1%.
When the valve reaches its maximum opening of 100.0% (Setpoint #122) the economizer function will use
other fans if they are available. In this example there are no fans that are associated only with economizer
but the VFD fan can now be used. At time delay of 120 seconds (Setpoint #125) be for the VFD will be
modulated. Following this initial delay the VFD will be opened to its minimum opening, Setpoint #54 of
20%.
At this point the unit state is ECONOMIZER ONLY, economizer valve is at 100% and VFD will be
modulated between its minimum (Setpoint #54) and it maximum (Setpoint #55). The delay between these
adjustments will be 45 seconds (Setpoint #115).
Once the VFD opening is equal to its maximum (Setpoint #55) there will be a delay of 240 seconds
(Setpoint #107). At this time the unit state will be changed and mechanical cooling will be enabled.