Schreiber Chillers 15MEDAC email - Manual (Page 7)

Condenser is designed to operate in a high ambient condition, 120F. This provides the
flexibility on the installation location without special requirement. However, proper
ventilation is still required. Refrigerant head pressure control is provided by a variable
speed drive. It will vary the speed of both fans based on the highest of the two head
pressure as measured by the controller.
Pumping System
The 15MEDGEN2 will have two identical chilled water pumps. The pumps have stainless
steel housings and impellers. Under normal operating conditions, one of the two pumps
will supply water to the heat exchangers. In the event of a pump failure the controller
will shut down the primary pump and start the backup pump. The reverse is also true.
When fault occurs on the back up pump, the pump will turn off and the primary pump
starts. When both pumps are failed, the controller will go into city water bypass mode,
if the equipment is available. The controller will automatically rotate the pumps
operation to balance operating time. The default change over time is 11PM, and it can
be changed.
The 15MEDGEN2 contains a large chilled water reservoir, 70 gallons. This chilled water
reservoir provides a thermal buffer to help maintain a constant chilled water
temperature to the system. The tank is a non pressurized rectangular tank that is
vented to the atmosphere. To prevent overflowing of the reservoir, a backflow kit it
provided.
The reservoir has 3 layers; a stainless steel inner layer, 1” of foam insulation, and a
powder coated steel outer layer. The top of the tank is made of a stainless steel
insulated and gasket lid.
The reservoir also includes a level sight glass, overflow, fill port for water and glycol,
and drain.
The chiller features two 2-horsepower pump that provide 20GPM @ 50-psi. The
advantage of the system provides a back up fluid supply if the operating pump fails. In
addition, a supply and a return connection provide an easy method to incorporate
emergency back up device such as city water switch over module. An automatic water
pressure valve is equipped to maintain water pressure NOT to exceed 45-psi.
Due to voltage fluctuation at site, a voltage/phase monitor will be installed on the
control system. The tolerance for this device is +10% at the rated condition. There
will be faults indication provided.
Each pump is connected with unions and hose fittings for easy removal if required.
There are discharge pressure gauge, flow switch, 40 mesh wye strainer, and a pressure
relief bypass valve.