The accumulation of dirt on a cooling coil is not ordinarily thought of as major source of trouble in an air-conditioning system. In fact, there is apparently some belief that coils cooling are "self cleaning" in that the condensate flowing down the coil washes off the dirt. The literature is also sparse in this area. The only reference in the ASHRAE handbooks is to maintenance of cooling coils; there is no mention of the significant effect of dirt buildup.

 However, cooling coils can become so obstructed with dirt that the air quantity and heat transfer will be reduced to the point where the system will no longer perform. This paper describes the history of such a system and the corrective measures that were eventually taken and makes recommendations for design and maintenance to reduce or eliminate the possibility of such obstructions occuring.

Units: I-P