York Millennium YK M3 M3 G4 THRU YK S6 S4 J2 - Manual (Page 55)

YORK INTERNATIONAL 55
FORM 160.49-O2
CONDENSERS AND COOLERS
GENERAL
Maintenance of condenser and cooler shells is impor-
tant to provide trouble free operation of the chiller. 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 fol-
lowing pages.
CHEMICAL WATER TREATMENT
Since the mineral content of the water circulated
through coolers and condensers varies with almost
every source of supply, it is possible that the water
being used may corrode the tubes or deposit heat re-
sistant scale in them. Reliable water treatment compa-
nies are available in most larger cities to supply a wa-
ter treating process which will greatly reduce the cor-
rosive and scale forming properties of almost any type
of water.
As a preventive measure against scale and corrosion
and to prolong the life of cooler and condenser tubes, a
chemical analysis of the water should be made prefer-
ably before the system is installed. A reliable water
treatment company can be consulted to determine
whether water treatment is necessary, and if so, to
furnish the proper treatment for the particular water
condition.
CLEANING COOLER AND CONDENSER TUBES
COOLER
It is difficult to determine by any particular test whether
possible lack of performance of the water cooler is due
to fouled tubes alone or due to a combination of
troubles. Trouble which may be due to fouled tubes is
indicated when, over a period of time, the cooling ca-
pacity decreases and the split (temperature difference
between water leaving the cooler and the refrigerant
temperature in the cooler) increases. A gradual drop-
off in cooling capacity can also be caused by a gradual
leak of refrigerant from the system or by a combina-
tion of fouled tubes and shortage of refrigerant charge.
An excessive quantity of oil in the cooler can also con-
tribute to erratic performance.
CONDENSER
In a condenser, trouble due to fouled tubes is usually
indicated by a steady rise in head pressure, over a
period of time, accompanied by a steady rise in con-
densing temperature, and noisy operation. These symp-
toms may also be due to foul gas buildup. Purging will
remove the foul gas revealing the effect of fouling.
TUBE FOULING
Fouling of the tubes can be due to deposits of two
types as follows:
1. Rust or sludge – which finds its way into the tubes
and accumulates there. This material usually does
not build up on the inner tube surfaces as scale,
but does interfere with the heat transfer. Rust or
sludge can generally be removed from the tubes by
a thorough brushing process.
2. Scale – due to mineral deposits. These deposits,
even though very thin and scarcely detectable upon
physical inspection, are highly resistant to heat
transfer. They can be removed most effectively by
circulating an acid solution through the tubes.
TUBE CLEANING PROCEDURES
BRUSH CLEANING OF TUBES
If the tube consists of dirt and sludge, it can usually be
removed by means of the brushing process. Drain the
water sides of the circuit to be cleaned (cooling water
or chilled water) remove the heads and thoroughly clean
each tube with a soft bristle bronze brush. DO NOT
USE A STEEL BRISTLE BRUSH. A steel brush may
damage the tubes.
Improved results can be obtained by admitting water
into the tube during the cleaning process. This can be
done by mounting the brush on a suitable length of 1/8"
pipe with a few small holes at the brush end and con-
necting the other end by means of a hose to the water
supply.
The tubes should always be brush cleaned before acid
cleaning.
ACID CLEANING OF TUBES
If the tubes are fouled with a hard scale deposit, they
must be acid cleaned. It is important that before acid
cleaning, the tubes be cleaned by the brushing pro-
cess described above. If the relatively loose foreign
material is removed before the acid cleaning, the acid
solution will have less material to dissolve and flush
from the tubes with the result that a more satisfactory
cleaning job will be accomplished with a probable sav-
ing of time.
COMMERCIAL ACID CLEANING
In many major cities, commercial organizations now
offer a specialized service of acid cleaning coolers
and condensers. If acid cleaning is required, YORK