Replacement of water
Because the cooling water system can be polluted by various 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 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 can 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
can 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 surfaces. 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 quality, temperature, flow
speed, metals used, existence of crevices and deposits and type of water system must be included.
For the complete corrosion preventive measure, consult a water treatment company.
Flow speed in tubes
As the water flow speed in the tubes is closely related to any existing corrosion, do not increase the
water supply rate more than recommended. If the flow speed reaches 11.6 in. to 13.3 in. (3.5 m to
4 m) 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 absorber), the eddy current at the inlet can corrode the tube.
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 install a strainer on the inlet side of the heat exchanger and clean the strainer periodically.
Model YHAU-CGN/H-CXR(M)Double Effect Direct Fired Small Absorption Chiller-Heater
160
