7
Optional Manual Isolation Valves
Standard modules are not supplied with isolation valves. Manual or
electrically actuated valves may be ordered as an option from
Multistack. Total Access modules are supplied with manual isolation
valves from the factory and may be upgraded to electrically actuated
valves as an option. Multistack recommends exercising the isolation
valves as part of annual maintenance.
Optional Hot Gas Bypass
As an option, hot gas bypass valves (Sporlan HGBE-8) can be provided
for each circuit. The valve is adjustable from 75 to 150 psi with a
standard setting of 120 psig. A screw on the pilot valve handles the
adjustment. Turning clockwise increases the valve setting; counter-
clockwise rotation decreases the valve setting.
Hot Gas Bypass Valve
Expansion Valves and Liquid Line Sight Glasses
(Standard unit.)
Butterfly Valve Actuator for Variable Flow shown on
standard module with extended headers.
Power Actuated
Butterfly Valve
Expansion Valve, Subcooling, Liquid Line Sight Glass
• Each circuit on a module has a thermal expansion valve located
between the water header pipes on the condenser side. During
factory run testing the valves are adjusted to maintain 10-12
degrees superheat. Check the superheat periodically to maintain
this range. Subcooling should normally be in a 10-15 degree
range. No external subcooler is used.
• The liquid line sight glass shows green on the indicator bulb if
no moisture is present in the refrigerant circuit. Yellow indicates
potential moisture.
• Sight glasses should show full during normal operation.
• Flashing in the sight glass indicates possible under-charge of the
circuit.
• Refer to the unit nameplate for refrigerant charge information.
Variable Flow and Power Actuated Butterfly Valves
For variable flow on the chilled or condenser water side, chiller mod-
ules must be ordered with power actuated butterfly valves.
Note:
The footprint of an array of standard modules will increase as
the valves add length. Total Access™ module footprint will not change.
1. Multistack recommends controlling the chiller pumps to maintain
pressure differential across the chiller, not the system. Control
based on system pressure will provide erratic results.
2. Chiller minimum flow bypass for the system can be programmed
in the master controller.
Heat Exchanger Isolation Valves on Total
Access™ Modular Chiller
Expansion
Valves
Sight
Glasses
