SECTION 9 - MAINTENANCE
JOHNSON CONTROLS
167
Form 201.28-NM1.1
Issue date: 08/06/2021
9
Charging refrigerant into a system
To charge the system with refrigerant, complete the
following steps:
1. With all system valves open and the Condenser
Drain and Economizer Valves open to 100% by
manually opening them in the Service Mode,
charge refrigerant vapor into the high side of the
system at the charging port on the liquid line. Con-
tinue charging vapor until the pressure is above
the freeze point of the chilled liquid. Once above
the freeze point, liquid can be charged according
to the recommended nameplate charge.
2. Reconnect the water piping to the water boxes.
3.
Close the evaporator drain valves and fill the
evaporator with water from the cooling loop.
4. Fill the water loop and check for leaks.
5. Close (0%) the Condenser Drain and Economizer
Valve in the Service Mode. Recycle the chiller
power.
6. Once the system is operating, the charge will
distribute itself throughout the system. Trim the
charge as needed to a level of about midway on
the evaporator sight glass while running full speed
for 15 minutes.
Microchannel coil cleaning
Regular cleaning is an essential part of maintaining
the integrity and heat transfer properties of heat ex-
changers. Failure to follow cleaning guidelines can re-
sult in heat exchanger damage, including leaks or loss
of performance. The cleaning procedures described in
this document are required to maintain the warranty of
the condenser coils.
Microchannel coils tend to accumulate less dirt inside
the coils than on the surface, which makes them easier
to clean than conventional round tube and fin coils.
The reduced depth and parallel tube layout of mi-
crochannel heat exchangers minimize the restriction
of cleaning water through the heat exchanger. This
provides a shorter and more direct path for cleaning
water to effectively carry away dirt and debris during
regular maintenance. During the cleaning process,
take care to avoid damage to the coils and the pro-
tective coatings. The following care points must be
followed during cleaning:
• DO NOT use high pressure water, such as a pres-
sure washer, to clean the coils. High pressure wa-
ter can damage the fins and the protective coatings
on the coil.
• DO NOT contact the coil with a hard object such
as a hose nozzle, hard vacuum nozzle or any other
tool. Hard objects or tools can cause mechanical
damage to the coil material and protective coat-
ings on the coil.
The required cleaning procedure is different depend
-
ing on the type of coil and protective coating supplied
with the coil. This section describes the proper proce-
dures to maintain the integrity of each type of coil.
Cleaning Procedure Required for Standard
and Environment Guard Microchannel Coils
Standard and Environment Guard microchannel coils
must be cleaned following this procedure at least once
quarterly to ensure that the integrity of the coils and
the warranty of the coils are maintained. In environ-
ments where coils become heavily fouled, a monthly
frequency of cleaning is recommended:
1. Remove surface debris such as dirt, leaves, in-
sects or fibers with a vacuum cleaner having a
soft brush attachment. When brushing debris off
the face of the coil a soft bristle brush, not wire,
can also be used. Do not scrape the coil with the
vacuum nozzle, air nozzle, or any other hard tool
2. Rinse the coil with potable tap water. Use a gentle
spray from a spray nozzle with a plastic end. Do
not contact the coil with the hose nozzle. Rinse
the coil by running water through every passage
in the heat exchanger surface until it is clean.
3. It is important to remove any excess water trapped
in the coils immediately after the final water rinse.
The condenser fans on the chiller can be run af-
ter the final water rinse to properly dry the coils.
Any excess water can also be removed by blow-
ing air through the coils with a hand held blower
or vacuum.
Cleaning Procedure for Environment Guard
Premium Microchannel Coils
Environment Guard Premium microchannel coils
must be cleaned following this procedure at least once
