The Trial Plant

Welcome to the Trial Plant.

This plant serves a single story office building for comfort cooling. The chiller yard is on ground level in the back of the building. The air handler is on the roof.

This plant has 1 air cooled scroll chiller, 1 air handler, 1 chilled water pump, and a controls system.

The Chiller is a Trane CGAM air cooled scroll chiller. See the manual for this chiller below.

The chilled water pump is independent from the chiller and controlled by the plant controls. It is a standard end-suction pump on a skid.

The air handler has a chilled water coil to control supply air temperature. The coil has a 3 way globe valve with an actuator to control flow through the coil based on supply air temperature. The air handler blower motor is on a VFD that is controlled based on supply air static pressure. The space has fan powered boxes with volume control dampers for zone control.

The controls systems is a simple programmable controller. It has a front end and directly controls the air handler and chilled water pump. It sends a start/stop signal to the chiller and monitors chilled water temperatures independently from the chiller sensors.

This plant runs on a business hours schedule of 6am to 7pm, then goes unoccupied overnight.

Setpoints:

Supply Air Setpoint (SASP): 55F

Supply Air Static Setpoint (SSSSP): 1.2"

Chilled Water Leaving Water Setpoint (LWTSP): 45F

SA: Supply Air Temperature

SASP: Supply Air Temp Setpoint

SS: Supply Air Static

SSSP: Supply Air Static Setpoint

HZ: VFD Output Hertz

CMD: Command

LWT: Leaving Water Temperature

LWTSP: Leaving Water Temperature Setpiont

EWT: Entering Water Temperature

OAT: Outside Air Temperature

COMP: Compressor

CKT: Refrigerant Circuit

LPST: Low Pressure Saturation Temp

HPST: High Pressure Saturation Temp

SLT: Suction Line Temperature

LLT: Liquid Line Temperature

EXV: Electronic Expansion Valve

SSH: Suction Superheat

AHU: Air Handler Unit

CH: Chiller

CHWP: Chilled Water Pump

BMS: Building Management System (Controls)

HOA: Hand-Off-Auto switch

DE CW: Drive End Clockwise rotation

DE CCW: Drive End Counterclockwise rotation

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