JOHNSON CONTROLS
103
SECTION 7 – MAINTENANCE
FORM 155.35-ICOM2.EN.CE/GB (1018)
DATE: 10/30/2018
7
CHEMICAL WATER TREATMENT
Since the mineral content of the water circulated
through the evaporator, condenser, absorber and the
water used may corrode the tubes or deposit heat resis-
tant 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
If the chilled / hot water line, and/or the cooling water
line are open systems, they must be cleaned or replaced
periodically. If the water is not treated at all in the wa-
ter line, the recommended intervals for replacement of
both types of water are:
• 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 metal
surfaces when they are corroded. They may also form
inert protective compounds over the metal surfaces.
For effective use of the corrosion inhibitors, the correct
type must be selected. The concentration must also be
determined according to the conditions in the chiller-
heater. Water quality, temperature, flow speed, metals
used, existence of crevices and deposits, and type of
water system are factors that must be considered. For
the complete corrosion preventive measure, consult a
water treatment company.
FLOW SPEED IN TUBES
Since the water flow speed in the tubes is closely relat-
ed to tube corrosion, do not increase the water supply
rate more than recommended. If the flow speed reaches
3.5 to 4 meters per second, the tubes may be damaged.
When changing the flow rate, contact your local John-
son Controls Service Center for help.
If the water supply rate is adjusted at the inlet side
of the heat exchanger, the turbulence at the inlet may
damage the tube. Be sure to control the flow rate on the
outlet side as well.
The turbulence caused by foreign matter in the heat ex-
changer is also a large factor of corrosion. Be sure to
install a strainer on the inlet side of the heat exchanger
and clean the strainer periodically.