Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
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The action and termination in the “DEF PUMP DOWN” state is the same as “DEF PREPMP OUT”. When this
state is terminated a variable step compressor will have its state changed to “HOLD”. A fixed step compressor’s
state will return to its state prior to the defrost cycle and the LLS will be turned on.
7.77. Control for Second set of Evaporator Pumps/Fans
A second set (bank) of Pumps/Fans have been added to the HVAC software. The purpose is to support systems
with two sets of pumps which provide flow to different circuits.
When the system is in a run condition, both lead pumps of each bank will be turned on to provide flow. If either of the
lead pumps fails, the running pump will be locked off and the backup pump for that respective bank will be started. The
circuits associated with the failed pump will be moved to a no flow state (disabled) as soon as flow is lost. If flow is
restored the circuit will be enabled again. If both pumps on a bank fail, then the circuit will be in a safety off state.
The 2 pump banks function independently, however, they both use common Setpoints to determine pump rotation,
pump lead, and safety times.
MCS-Config Setup 7.77.1.
Evaporator Info panel under the MAG HVAC V8 Screen:
The Pump/Fan section now consists of entries for bank A and bank B.
Select Output and Sensor Inputs per circuit panel under the Circuit Base button:
In the Flow column, select the flow indicators for the individual pump bank control.
In the above example:
Pump bank A has 2 pumps, Pump 1-A and Pump 2-A, and the flow indicator is Flow A. If Flow A indicates that
there is no flow, then circuits 1 and 3 will be disabled.
Pump bank B has 2 pumps, Pump 1-B and Pump 2-B, and the flow indicator is Flow B. If Flow B indicates that
there is no flow, then circuits 2 and 4 will be disabled.