9 Maintenance notes
Cleaning agents for heat exchanger
SMGB0137 rev.0 - 05/2021
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9.6 Cleaning agents for heat exchanger
The aluminium fin surfaces of the heat exchanger for all the indoor units of packaged air conditioners are coated with
a hydrophilic coating to prevent the increase of airstream resistance due the occurrence of condensing water during
cooling operation.
However, if the Aluminium fin’s hydrophilic is decreased by the adhesion of contaminants, etc., the following
phenomenon will happen.
Dew will adhere between each aluminium fin space (Bridging Phenomenon)
Increase of airstream resistance
Decrease of the airflow volume
Decrease of cooling capacity
In some cases, dew may be splashed from the indoor unit
In order to avoid the malfunction of the unit, we recommend the use of cleaning agent for the aluminium fins.
9.6.1
Recommended specifications of cleaning agents for aluminium fins
Effect on hydrophilic coating
No effect
Effectiveness against specific
types of dirt
Grease and Oil
Specially effective
Tar
Effective
White powder (*1)
Ineffective
Possibility of occurrence of cracking (*2)
Low
pH of the solution
Alkaline or Weak alkaline
Requirement of dilution
Yes or No
Personal Protection Equipment (PPE) to be used in handling (*3)
Mask, Glasses, Gloves
(*1): The hydroxide caused by the reaction of aluminium fins and the water condensed on the surface of the fins.
(*2): The possibility of occurrence of cracking was also examined taking into account the results of the examination of the
possibility of occurrence of cracking in Acrylonitrile Butadiene Styrene (ABS) and Polystyrene (PS).
(*3): Personal Protection Equipment (PPE) must be used whenever manipulating chemical products, in order to ensure
safety.
9.6.2
Particularities and benefits
HITACHI has ben tested the effect of cleaning benefits using special fin cleaners for hydrophilic coated fins on the indoor
units. Those tests were focused on the wettability, and confirmed as follows:
• Cleaning aluminium fins makes its hydrophilicity possible to recover.
• The hydrophilic coating is not damaged even if it’s washed repeatedly by using special cleaning special agents for
hydrophilic aluminium coatings.
9.6.3 To consider
Before washing aluminium fins, protect the fan motor, the electrical box, the connectors and, in general, all the wiring
of being splashed with the cleaning products and water. In addition, before starting an air-conditioning operation, after
washing the aluminium fins, be sure that there is no splashing water on those items.
If the cleaning agents are used incorrectly, it will cause damage to aluminium fins. When using those products, pay
special attention to the indications referred on each instructions manual
