Troubleshooting guide

MAGNUM VERSION 8 MANUAL REVISION 3.1
155
# Name Description
152 HP OVERHEAT This Setpoint is only used when the heat pump option has been selected in the ‘Unit Type’
box in the ‘General Information’ panel under the MAG V8 screen. It is used to protect
against a heat pump with unloaders (or variable speed) from overheating. When this
Setpoint is active and the leaving temperature sensor is greater than this Setpoint minus
3.0° Fahrenheit, then the compressor will enter HIGH TEMP UNLOAD state. The
temperature must drop to less than this Setpoint minus 4.5° Fahrenheit before the
system will move to the holding state.
153 SftyUnld Del The time delay in seconds between compressor capacity adjustments when safety
unloading.
154 VFD Sfty Adj The VFD percentage adjustment to be made after every amount of time in Setpoint
#153 “SftyUnld Del” when safety unloading.
155 LO REF TMP If active, the Magnum checks for low refrigerant temperature. If the refrigerant temperature is
less than the value of this Setpoint for the specified period of time, a safety trip occurs.
156 LO REF UNLD
The purpose of this Setpoint is to take preventative action before a low refrigerant
temperature safety trip. The compressor will unload when the refrigerant temperature is
less than the value of the Setpoint #155 “LO REF TMP” plus this Setpoint. The
compressor state will be changed to LO TMP UNLOAD. The compressor will remain in
this state until the refrigerant temperature is above the value of Setpoint #155 “LO REF
TMP” plus twice the value of this Setpoint. The compressor state change to LO TMP
HOLD.
157 HP LoSuctAdj
(Only HVAC)
This Setpoint is only used when the heat pump option has been selected in the ‘Unit Type’
box in the ‘General Information’ panel under the MAG V8 screen. When in heating mode,
the low suction value Setpoint #77 “LOW SUCTION” is reduced by the value of this
Setpoint.
COV LIFT TEMP
(Only CENT)
Minimum change to the saturated lift before calculating a new minimum speed.
B-PUMP DELAY
(Boiler/Pump Control)
The time delay expressed as seconds between making decisions as to pump settings.
158 DEF TRIG TMP
(Only HVAC)
If a defrost option has been specified and either coil #1 or coil #2 temperature is less than or
equal to this Setpoint a defrost cycle will be started if sufficient time has elapsed since the
last defrost.
B-STAGE DELY
(Boiler/Pump Control)
The time delay expressed as seconds between making decisions as to boiler stage settings.
159 DEF TRIG DEL
(Only HVAC)
Time in minutes between defrost cycles.
B-VFD DELAY
(Boiler/Pump Control)
The time delay expressed as seconds between making decisions as to pump VFD setting.
‘Sec. to Ignore Safety’ field: contains the minimum valve setting. For example if this cell
contains 500, the valve will initially be set to 50.0% and it will never be less than this
value.
‘Window to extend Safety Time(sec)’ field: contains the maximum valve setting. This will
normally be 1000 for 100.0%.
160 DEF REV DEL
(Only HVAC)
If a reversing valve is used, this is the delay in minutes the system must wait once the valve
has been opened before the defrost cycle can continue.
B-VFD TARGET
(Boiler/Pump Control)
The target flow that is to be maintained. This can be a differential if both input and output
pressures sensors are specified or the actual flow of the input if only sensor specified.
‘Time(sec)’ field: contains the delay in seconds before another pump can be turned on once
the valve gets to 100.0%
‘Sec. to Ignore Safety’ field: contains high dead band for the control zone. This is added to the
value of this set point. In this example the high dead band will be 63.0.
‘Window to extend Safety Time(sec)’ field: contains low dead band for the control zone. This
is subtracted from the value of this set point. In this example the low dead band will be
57.5.
‘Safety Time Extension’ field: contains the maximum valve adjustment that can be made at
one time. In this example the maximum adjustment to the valve will be 3.0%..