JOHNSON CONTROLS
151
SECTION 7 – MAINTENANCE
FORM 155.32-ICOM1.EN.GB
ISSUE DATE: 10/13/2017
7
CHEMICAL WATER TREATMENT
Since the mineral content of the water circulated
through the evaporator, condenser, and absorbers var-
ies, the water used may corrode the tubes or deposit
heat resistant scale in them.
Perform a chemical analysis of the water before the
system is installed. Consult a reliable water treatment
company to determine if treatment is necessary. If it
is, the company can provide treatment for the water to
help prevent damage to the tubes.
REPLACEMENT OF WATER
Since the cooling water system can be polluted by vari-
ous factors, it must be cleaned and the water it in must
be replaced periodically. Generally, if the water is not
treated at all by the cooling tower, the recommended
interval to replace the cooling water is:
District polluted with sulfurous acid gas --- 5 days
Common district --- 10 days
If the water is blown manually or automatically, the
replacement period may be lengthened as follows.
District polluted with sulfurous acid gas --- 1 month
Common district --- 1 month
TREATMENT FOR LONG STOPPAGE OF THE
ABSORPTION CHILLER-HEATER
If the absorption chiller-heater is stopped for a long
time, bacteria in the water or in the tubes may grow.
The bacteria can corrode the tubes. When stopping the
chiller-heater for more than 15 days, drain the water
from the absorber, condenser, and evaporator through
the drain valve at the bottom of the waterbox.
CHEMICAL TREATMENT
Corrosion inhibitors are attracted chemically to the
metal surfaces when the latter are corroded or they
form inert protective compounds over the metal sur-
faces. For effective use of the corrosion inhibitors,
types of them must be selected and their concentration
must be determined according to the conditions of the
chiller-heater system. In those conditions, water qual-
ity, temperature, flow speed, metals used, existence of
crevices and deposits and type of water system must be
included. For the complete corrosion preventive mea-
sure, consult a water treatment company.
FLOW SPEED IN TUBES
Since the water flow speed in the tubes is closely re-
lated to any existing corrosion, do not increase the wa-
ter supply rate more than recommended. If the flow
speed reaches 3.5 to 4 meters per second, the tubes
may erode. When changing the flow rate, contact your
local Johnson Controls Service Center.
If the water supply rate is adjusted at the inlet side of
the heat exchanger (evaporator, condenser, and absorb-
er), the eddy current at the inlet may corrode the tube.
Be sure to control the flow rate on the outlet side.
The eddy current caused by foreign matter in the heat
exchanger is also a factor in corrosion. Be sure to in-
stall a strainer on the inlet side of the heat exchanger
and clean the strainer periodically.
