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REGULAR MAINTENANCE ITEMS
Air Filters
The air filter section is an integral part of the environmental control system, designed within the unit for
easy front accessibility. An initial set of filters are factory installed in the unit. The filters are 2-inch (50
mm) deep, disposable, pleated design, extended surface, nonwoven, reinforced cotton fabric;
supported and bonded to welded wire grid; enclosed in cardboard frame design rated not less than
MERV 8 per ASHRAE Std. 52.2. A filter differential switch for alarm activation is included.
Air filters should be checked on a regular basis and changed when they become dirty. This will ensure
efficient operation of the unit. Spare air filters should be kept in stock as these tend to be a frequently
replaced maintenance item. Air filters may require changing as often as monthly dependent on room
or space conditions. New installations with construction dust will quickly clog filters requiring new filters.
The Mini-dap4 controller monitors the air filters status. An optional dirty filter alarm will be enunciated
on the controls display screen. Although the unit may display a dirty filter alarm, this should not be relied
on as the only determinant for replacing air filters. A misadjusted air filter differential pressure switch
may not give a proper indication of a clogged filter.
To check the air filter pressure differential pressure switch for proper adjustment, temporarily cover
approximately 75% of the return air opening using heavy cardboard or similar material. The alarm
should energize when 75% of the air is blocked, simulating dirty filters. If the alarm energizes
prematurely or does not energize at all, the pressure switch should be adjusted. All side panels must
remain closed when determining if an adjustment is necessary.
WARNING:
Air filters that require changing can restrict airflow and create
problems such as coil icing or poor air distribution.
Belts
Belt tension should be checked regularly (monthly) to ensure proper tension. If tightening is required,
loosen the four (4) motor mounting bolts. Turn the adjustment screw on the end of the motor mounting
channel until the proper belt tension is attained. Retighten the four (4) mounting bolts. Damage can
occur to belts that are overtightened. The amount of play in a typical drive set should be 1/2 inch (13
mm). When tightening the belts make sure the pulley alignment is true. If the belts are over tightened
or if the pulleys are misaligned the bearing and belt life can be significantly shortened.
Bearings
Blower bearings used with Mini-Plus ceiling units are permanently lubricated and do not require
maintenance.
Some motors may have Zirk type grease fittings on the bearings. If so, the motor should be greased at
least annually. Use NLGI grade 2 lithium or lithium complex grease. Care should be taken to avoid over
greasing. Only one or two pumps from a manual gun are required.
Summary of Contents for DA PA-04
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