Fan Replacement - Baltimore Aircoil Company Trillium Series Operating And Maintenance Instructions Manual

HEAT EXCHANGER COIL
The finned heat exchanger coil is susceptible to corrosion and entrapment of airborne particulates (coil fouling).
The speed of coil fouling can be reduced, and the service lifetime of the finned coil can be extended, if the pre-
cooling media is kept in place also during cold seasons, to act as air filter.
The heat exchanger coil requires periodic cleaning to maintain the highest operating efficiency possible under the
environmental conditions in which the dry unit operates. Regularly scheduled coil cleaning makes a significant
contribution to extending equipment lifetime and is an excellent source of energy conservation.
Periodic cleaning of the heat exchanger coil can be accomplished by a vacuum cleaner and/or pressurised air
stream. In polluted environments cleaning will require commercially available coil cleaning agents. Cleaning coils
by spraying them with water may remove large deposits but do little to remove pollutants. Removing dirt and salts
requires a detergent to break the bond between the soil and the surface of the heat exchanger. However, if water
spray is applied, the water pressure must never exceed 2 bar and the water jet must never be applied at an angle to
the surface of the fin, but only in parallel to it.
Selecting a coil cleaner is important since the cleaner must neutralise and remove deposits on the surface of the
coil. BAC does not recommend the use of alkaline and acidic coil cleaners. These coil cleaners can cause foaming
action (oxides or hydroxides of aluminium) resulting in the stripping away of minute layers of the base alloy and the
attached soil. Most of these foaming cleaners are harsh and known as reactive cleaning products. One way to
recognise this type of cleaner is that normally it will be labelled as corrosive. The base ingredient of a coil cleaner
should not be so harsh that it attacks the metal, coil coating or the personnel applying the cleaner.
An important concern when applying coil cleaners is rinse-ability. Most hydroxides tend to cling the surface unless
sufficient wetting agents have been added to the formula to reduce surface tension of the solution. If the solution
does not have enough wetting agents and is not rinsed thoroughly from the surface, the residual material can settle
at the fin/tube interface and continue to attack the fin.
BAC recommends the use of the more sophisticated cleaners, known as a "surfactant system". They reduce
surface tension, penetrate, emulsify, and dissolve the soils without the base alloy. Surfactant systems are safe for
the coil alloy, they are free rinsing, they lift and remove deposits better than alkaline cleaners, and they are
environmentally safe, as well as safe and easy to apply and rinse. Surfactant systems are almost always non-
corrosive.

Fan replacement

In case of replacement, any safety hazards stemming from the fan must be re-evaluated once it is installed on the
cooler.
Observe the following when working on the fans:
• Do not make any modifications, additions or conversions to the fan without the approval of the cooler
manufacturer.
• Terminals and connections may have residual voltage after unit shutdown.
Wait five minutes after disconnecting the voltage at all poles before opening the fan.
• In the event of failure, there is electric voltage at the rotor and impeller.
Do not touch the rotor and impeller once they are installed.
• Shut down the fan immediately if you detect a missing or ineffective protective feature.
The fans are controlled via a digital bus system (MODBUS RTU). For the bus communication each fan needs to
be assigned a unique address, starting with "2, 3, 4.......", leaving 1 free for any replacement fan. The sequence of
the above system is shown on the diagram below.
In case of a fan replacement it will be necessary to specify the assigned fan number shown on the diagrams, so
that the replacement fan will be programmed accordingly.
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