Preventive Maintenance
An AHU system will operate efficiently and provide suitable comfort conditions and ensure good indoor air quality only when it is properly adjusted and maintained.
The AHU system operator's must have an adequate understanding of the overall system design, its intended function, and its limitations. The preventive maintenance program must be properly budgeted and implemented, not merely planned on paper. It is expected a well-implemented preventive maintenance plan will improve the functioning of the mechanical systems and usually save money when evaluated on a lifecycle basis.
Sometimes regular maintenance may be put off until breakdowns occur or complaints arise. This type of program represents a false economy and often increases the eventual cost of repairs. Poor filter maintenance is a common example of this phenomenon. Filters that are not changed regularly can become a bed for fungal growth, sometimes allowing particles or microorganisms to be distributed within the building. When filters become clogged, the fans use more energy to operate and move less air.
If the filters are an inexpensive, low-efficiency type that becomes clogged and then "blows out," the coils then accumulate dirt, causing another increase in energy consumption. Poor air filter efficiency and poor maintenance may cause dirt to build up in ducts and become contaminated with molds, possibly requiring an expensive duct cleaning operation.
General elements of a preventive maintenance plan include:
- periodic inspection, cleaning, and service as warranted;
- adjustment and calibration of control system components; and
- maintenance equipment and replacement parts that are of good quality and properly selected for the intended function.
Critical AHU system components that require preventive maintenance in order to maintain comfort and deliver adequate ventilation air include:
- outside air intake are inspected for nearby sources of contaminants
- Air distribution dampers are maintained clear of obstructions and operating properly.
- air filters have the pressure drops monitored and replacement or cleaning is performed regularly
- drain pans are inspected and cleaned to ensure proper drainage
- cooling coils are inspected and cleaned
- Fan motor and belts are inspected and replaced as warranted
- dehumidification equipment and cooling towers are inspected, cleaned and water treated according to schedule.
- distribution systems or pathways are inspected and cleaned as needed
- exhaust fans are inspected and cleaned
- The preventive maintenance plan and operations manuals are updated when equipment is added, removed or replaced.
Indoor air quality complaints can also arise from inadequate housekeeping that fails to remove dust and other dirt. On the other hand, cleaning materials themselves produce odors and emit a variety of chemicals. As they work throughout a building, cleaning staff or contractors may be the first to recognize and respond to potential IAQ problems.