ClimaCool UCA Manual - Manual (Page 28)

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28
Heat Exchangers
Draining
When performing standard maintenance procedures such
as fl ushing a heat exchanger, it will be necessary to close
off a section of a module. This can easily be done if factory
mounted water isolation valves are provided.
Back Washing
It may become evident from the recorded weekly log
data that the performance of the chiller is gradually
degrading. This could be due to a buildup of debris or
sludge obstructing the free passage of fl ow through the
heat exchangers. This debris can be removed by a back
washing process which involves the introduction of a forced
violent backwards fl ow through the heat exchanger using a
carefully formulated fl ushing solution. To be eff ective, this
back fl ow should be slightly higher than the normal fl ow,
and in the opposite direction. The diffi
culties and practicality
of this method depends on the back wash pumping system
itself. Another method is to back fl ush each heat exchanger
using city water as opposed to system water (see Figure
1 on page 29 – City Water Cleaning Arrangement). The
back washing procedure is accomplished by isolating each
individual heat exchanger and introducing the city water
using a connection hose to the 3/4” service port to fl ow in
an opposite direction from the normal heat exchanger fl ow
direction. On the opposite 3/4” service port, connect a drain
hose continuing back fl ow until all debris is removed.
Chemical Clean In Place Washing Without Water
Isolation Valves
Chemical Clean in place washing will typically provide
the best debris removal, even from severely clogged
heat exchangers. In order to clean the heat exchangers
for modules WITHOUT water isolation valves, it will be
necessary to mechanically and electrically isolate each
module separately from the bank of modules. The rest of
the chiller modules will need to be disabled during this
cleaning procedure as the fl ow through the main bank
header will be interrupted. The cleaning tank, pump and
pump strainer should be arranged in the manner shown
in Figure 2 on page 29 - In Place Cleaning Arrangement.
The fl ow of the cleaning is arranged in the opposite fl ow
to the normal operational direction. Connection points
are provided using the 3/4” service ports at each heat
exchanger. The cleaning solution used can be either a
detergent or hot water to remove particles and simple
cleaning. If correct water treatment has been implemented,
this should provide adequate cleaning for most situations.
The solution can be pumped through the heat exchangers
and allowed to “soak” for a time and then pumped again.
Upon successful cleaning of a module, proceed to isolate
a second module separately from the bank to repeat the
cleaning process.
Chemical Clean In Place Washing With Water
Isolation Valves
Chemical Clean in place washing will typically provide
the best debris removal, even from severely clogged
heat exchangers. It is only necessary to mechanically and
electrically isolate one chiller module at a time. The rest of
the chiller modules can continue to operate to satisfy the
cooling load required. The cleaning tank, pump and pump
strainer should be arranged in the manner shown in Figure
2 on page 29- In Place Cleaning Arrangement. The fl ow of
the cleaning is arranged in the opposite fl ow to the normal
operational direction. Connection points are provided
using the 3/4” service ports at each heat exchanger. The
cleaning solution used can be either a detergent or hot
water to remove particles and simple cleaning. If correct
water treatment has been implemented, this should provide
adequate cleaning for most situations. The solution can
be pumped through the heat exchangers and allowed to
“soak” for a time and then pumped again. If it is required
to remove carbonates, then an acidic wash should be used.
A 2% solution of phosphoric or sulfamic acids in pure water
are generally acceptable. These acid solutions should only
be allowed to circulate within the heat exchanger for 10 to
15 minutes, followed by a thorough pure water fl ush for 10
to 15 minutes. Hydrochloric or sulfuric acids must not be
used. In any case, consult the chemical supplier to establish
the correct formulation and handling process. The materials,
which will be exposed to the wash, are stated on page 16 –
Water Treatment.
Once the washing is complete, the solution should be
fl ushed out completely by pumping clean, fresh water
through the chiller. To achieve a reasonable level of dilution,
it may be required to change the water several times. After
cleaning, the water quality and water treatment should be
confi rmed.