Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1

 If during mechanical cooling mode the ambient temperature drops below the offset in Setpoint #119,

then the economizer function will begin. Note: the Unit State will not change, the economizer valve will

be modulated as described above, fans directly associated with the economizer will be used, and no

fans associated with the condensers will used.

 The control rate of change is always checked before an adjustment to the valve is made. The

purpose is to not change the valve opening if the temperature is moving toward the target at an

acceptable rate.

Outside Air Supply Economizer

7.40.3.

If the purpose of the economizer is to provide outside air, then there will be no fans associated with the

economizer and no condenser fans will be used. In this setup the economizer valve opening will never be

less than the value of Setpoint #121 ”Eco MIN VLV%”. This is required to supply the minimum of outside

air.

Mechanical Cooling Enabled

7.40.4.

Once mechanical cooling has been enabled, the economizer will control only the individual compressor

condenser fans of compressors that have not been started. The discharge pressure will control all others.

The percentage of the economizer valve opening will not be decreased. It will remain at its maximum

setting until all stages of mechanical cooling are off.

Example: Fluid Cooler with VFD condenser fan

7.40.5.

The economizer AO has been selected and there are no separate economizer fans.

The condenser type is common with VFD control and the Fluid Cooler Economizer option has been

enabled. The VFD of the condenser fan will be controlled by the economizer function unless any

compressor is running. If a compressor is running the VFD control will be based upon the highest

discharge pressure.

Assume the following setup:

Setpoint # Name Value

1 SPPLY TRGT 44.0F

2 CTRL ZONE+ 2.0F

3 CTRL ZONE- 1.0F

27 MAX ROC- -.6F

28 MAX ROC+ .6F

54 CND MIN OPEN 20.0%

55 CND MAX OPEN 100.0%

107 ECON-MECHdly 240s

115 EconVFDdelay 45s

Analog output Name

AO M-1 3 WAY VLV

AO M-2 VFD