Cleaning technology of the HVAC systems.

The aim of the experiment was to study the efficiency of three duct cleaning methods. The methods used were ( 1) rotating brushes, (2) compressed air cleaning, and (3) wiping by hand. The air handling systems under investigations had been in use 26 and 30 years after the construction phase and the systems had not been cleaned since buildings were completed. Accumulated amount of dust in the supply air duct was determined by BM-Dustdetector, tape method, and by visual inspection before and after cleaning. The amount of dust on the duct surface was decreased with all three cleaning methods. The best cleaning result was achieved by hand wiping. However, significant amount of residual dust was found on duct surfaces after cleaning with all three cleaning methods. The level of dust on the bottom surface of the supply air duct was on average 15-21 % after cleaning. Significant differences in the cleaning result of the ducts were observed between the methods.