Pre-Start Checkout - G&D VERTICAL AIR Series Installation Manual & User Manual

I I NSTALLATION GUIDE • USER MANUAL I

PRE-START CHECKOUT

When installation is complete, but prior to putting the unit into service, the following prestart procedures must be
reviewed and verified correct:
CAUTION: COMPRESSOR DAMAGE!
Do not operate the unit with the compressor, oil discharge, liquid line service valves and the manual shutoff on the
refrigerant supply to the condenser "CLOSED".
Failure to "OPEN" all valves prior to starting the compressor may cause serious damage.
Check the power supply voltage to the unit at the main power distribution block. Voltage must be within the

voltage utilization range stamped on the unit nameplate. Voltage imbalance must not exceed 2 percent.
 Check the unit power phasing to be sure that it has been installed in phase with the phase monitor.
 Fill the chiller reservoir with the proper solution of freeze inhibitor. Vent the system while it is being filled.
CAUTION: PROPER WATER TREATMENT!
The use of untreated or improperly treated water in the chiller may result in scaling, erosion, corrosion, algae or
slime. It is recommended that the services of a qualified water treatment specialist be engaged to determine what
water treatment, if any, is required. G&D assumes no responsibility for equipment failures which result from
untreated or improperly treated water, or saline or brackish water.
 Close the fused‐disconnect switch(es) that supplies power to the main distribution block.
START-UP: OPTIMIZING REFRIGERANT CONDITIONS
Please note: This chiller utilizes a PID formula to maintain the fluid temperature as close to the set point as possible.
At times, the compressors may continue to run even if the fluid temperature is below the set point. This is normal.
Note: Once the system has been operating for approximately 30 minutes and has become stabilized, complete the
remaining start‐up procedures, as follows:
Check and record the compressor refrigerant suction and discharge pressures.

 Check the liquid line sight glasses after sufficient time has elapsed to stabilize the chiller. The refrigerant flow
past the sight glasses should be clear. Bubbles in the refrigerant indicate either low refrigerant charge or
excessive pressure drop in the liquid line or a stuck open expansion valve or ice formation in the evaporator. A
restriction in the line can sometimes be identified by a noticeable temperature differential between the two
sides of the restriction. Frost will often form on the line at this point. Proper refrigerant charges are listed on
the unit nameplate.
Note: Important! A clear sight glass alone does not mean that the system is properly charged. Also check system
subcooling, and unit operating pressures.
 A shortage of refrigerant is indicated if operating pressures are low and subcooling is also low. If the operating
pressures, sight glass, superheat and subcooling readings indicate a refrigerant shortage, gas‐charge refrigerant
into each circuit, as required. With the unit running, add refrigerant vapor by connecting the charging line to
the suction accumulator and service port until operating conditions become normal. Slowly add refrigerant.
G&D CHILLERS, INC.
GD-VA-R2022C
•
VERTICAL AIR SERIES
19