Quantech QTC40160, Installation Operation & Maintenance

Page: 95 / 188

Quantech
95
Form QTC4-NM2
Issue date: 05/12/2023
6
Section 6 - Commissioning
Preparation
Commissioning of this unit must only
be carried out by Quantech authorized
personnel.
Commissioning personnel must be thoroughly familiar
with the information contained in this document be-
fore starting the unit.
The following basic checks must be made with the
customer power to the unit switched OFF.
Correct electrical lock out and tag out
procedures must be followed.
Inspection
Inspect unit for installation damage. If found, take ac-
tion and repair as appropriate.
Refrigerant charge
Packaged units are normally shipped as standard
with a full refrigerant operating charge. Check that
refrigerant pressure is present in both systems and
that no leaks are apparent. If no pressure is present,
a leak test must be undertaken, the leaks located and
repaired.
Do not evacuate or liquid charge with static water
in the evaporator. Turn the pump on. Take care to
liquid charge slowly to avoid excessive thermal stress
at the charging point and to ensure the refrigerant
temperature in the evaporator does not go below the
freezing point with liquid refrigerant in the evaporator.
After breaking the vacuum, charge into the low side with
the Condenser Drain Valve open and the chilled liquid
pump ON to the full operating charge, as detailed in
Section 5 - Technical data .
Correct system refrigerant charge
Always check the charge on a system when op-
erating for several minutes at full speed with the
system stable. Stable conditions are defined as
operation without fan cycling, economizer cycling,
VI solenoid cycling, or any other system transient
conditions. Ideal refrigerant charge will be reached
when the refrigerant level in the evaporator is near the
middle of the evaporator sight glass.
Refrigerant must not be added or
removed unless the level is at the bottom
or the top of the glass. It is not necessary to
weigh charge unless the entire charge has
been lost. The ease of charging is possible
since the microchannel coils hold only
a small amount of refrigerant charge.
Charge must be added as liquid with the
pump ON and liquid flowing through the
evaporator.
Service and oil line valves
Open each compressor oil, economizer, and discharge
ball and/or service valves. If valves are of the back-seat
type, open them fully (counter-clockwise) then close
one turn of the stem to ensure operating pressure is fed
to pressure transducers.
Compressor oil
To add oil to a circuit - connect a Quantech hand oil
pump (Part No. 470-10654-000) to the 1/4 in. (6.35
mm) oil charging valve on the oil separator piping with
a length of clean hose or copper line, but do not tighten
the flare nut. Using clean oil of the correct type (“L”
oil), pump oil until all air has been purged from the
hose then tighten the nut. Stroke the oil pump to add
oil to the oil system. While the compressor is running
at full speed, the oil level is visible in the sight glass
of the oil separator. Approximately 2 gal to 3.7 gal
(7.5 L to 14.0 L) are present in each refrigerant
system.
Avoid levels in either oil separator that are above the
middle of the top sight glass. This may cause excessive
oil carryover in the system.
High oil concentration in the system may cause
nuisance trips resulting from incorrect readings on the
level sensor and temperature sensors. Temperature sen-
sor errors may result in poor liquid control which will