JOHNSON CONTROLS
63
SECTION 5 – MAINTENANCE
FORM 160.81-NOM1
ISSUE DATE: 10/3/2020
5
CONDENSERS AND EVAPORATORS
General
Maintenance of condenser and evaporator shells is im-
portant to provide trouble free operation of the unit.
The water side of the tubes in the shell must be kept
clean and free from scale. Proper maintenance such as
tube cleaning, and testing for leaks, is covered on the
following pages.
Chemical Water Treatment
Since the mineral content of the water circulated
through evaporators and condensers varies with almost
every source of supply, it is possible that the water be-
ing used may corrode the tubes or deposit heat resistant
scale in them.
Reliable water treatment companies are available in
most larger cities to supply a water treating process
which will greatly reduce the corrosive and scale form-
ing properties of almost any type of water.
As a preventive measure against scale and corrosion
and to prolong the life of evaporator and condenser
tubes, a chemical analysis of the water should be made,
preferably before the system is installed. A reliable wa-
ter treatment company can be consulted to determine
whether water treatment is necessary, and if so, to fur-
nish the proper treatment for the particular water condi-
tion.
CLEANING EVAPORATOR AND CONDENSER
TUBES
Condenser Tubes –
The standard condenser tubes used
in YORK YR Chillers are internally enhanced copper
tubes.
If the equipment is located in an unheated
area that is susceptible to freezing, the
water must be drained from the condenser
to prevent tube failure from freezing.
Proper condenser water treatment can eliminate or sig-
nificantly reduce the formation of scale on the water-
side of the condenser tubes.
Maintain a minimum condenser water flow rate through
the tubes of at least 3.33 ft./sec. (1 meter/sec.). Through
tube water velocity should not exceed 12 ft./sec.
(3.6 meter/sec.).
Condenser tubes must be maintained to provide proper
chiller operation. Condenser Approach Temperature is
a useful tool to monitor the performance of the con-
denser. By recording and logging the Condenser Ap-
proach Temperature as part of the chiller maintenance
program, this will provide a warning that the waterside
condenser tubes are fouled and require cleaning.
Condenser Approach Temperature is the difference be-
tween the Condenser Leaving Water Temperature and
the Saturated Condensing Temperature.
If the approach increases above 10°F (5.6°C), or dur-
ing the annual condenser inspection and the tubes are
observed to be fouled, the tubes will require cleaning.
For condenser fluids other than water consult with the
local Johnson Controls Service Office for the correct
condenser approach.
CONDENSER WATER SIDE TUBE CLEANING
PROCEDURE
Two methods are used for waterside tube cleaning to
remove the scale; chemical and mechanical cleaning
procedures. The composition of the scale will deter-
mine which method will be most effective to remove
the scale and dirt.
Consult with the local Johnson Controls Service Office
for a recommendation of the method(s) used in the lo-
cal area.
Chemical Cleaning Procedure
Chemical cleaning is an effective method to remove
scale from internally enhanced copper tubes. However,
a company knowledgeable with the chemical cleaning
procedure should be contracted or consulted. Follow
the chemical cleaning company recommendations con-
cerning solution cleaning strength and time duration of
the cleaning process.
Serious damage to the condenser tubes
will result if the chemical cleaning pro-
cedure is improperly applied.
Mechanical tube cleaning must always
follow a chemical cleaning procedure.
