ClimaCool UGW Manual - Manual (Page 45)

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Heat Exchangers
Draining
When performing standard maintenance procedures
such as flushing 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 .
Access to a floor drain is helpful when performing standard
maintenance procedures .
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 flow through the heat
exchangers . The debris can be removed by a back washing
process which involves the introduction of a forced, violent
backwards flow through the heat exchanger using a
carefully formulated flushing solution. To be effective, this
back flow should be slightly higher than the normal flow,
and in the opposite direction. The difficulties and practicality
of this method depend on the back wash pumping system
itself. Another method is to back flush each heat exchanger
using city water as opposed to system water (see Figure
14 – City Water Cleaning Arrangement on Page 44) . The
back washing procedure is accomplished by isolating each
individual heat exchanger and introducing the city water
using a connection hose to the ¾” service port to flow in
an opposite direction from the normal heat exchanger flow
direction . On the opposite ¾” service port, connect a drain
hose to run to a suitable floor drain. Continue the back flow
until all debris is removed . Warning: Water valves must be
re-opened after flushing is complete.
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 flow through the main bank
header will be interrupted . The cleaning tank, pump and
pump strainer should be arranged in the manner shown in
Figure 15 - In Place Cleaning Arrangement (page 44). The
flow of the cleaning is arranged in the opposite flow to
the normal operational direction . Connection points are
provided using the ¾” 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 module at a time . The rest of the
chiller modules can continue to operate to satisfy the
required cooling load . The cleaning tank, pump and pump
strainer should be arranged in the manner shown in Figure
15 - In Place Cleaning Arrangement (page 44). The flow of
the cleaning is arranged in the opposite flow to the normal
operational direction . Connection points are provided
using the ¾” 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 flush 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 exposed to the wash are stated on
page 15 – Water Treatment .
Once the washing is complete, the solution should be
flushed 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 confirmed.