Manual 2100-670
Page
16 of 32
FIGURE 18
Verifying Differential Airflow Status
Filters
The unit is equipped with two (2) 20" x 30" x 2" MERV
8 filters. The filters slide into position making them easy
to service. The filters can be serviced from the outside
by removing either the right or left filter access panel.
Dirty Filter Switch
These units are equipped with a differential pressure
switch to indicate when the filter(s) needs to be
replaced (see Figure 17). The dirty filter switch
measures the pressure difference across the filter
through silicone tubing routed to the blower and vent
areas of the unit.
The switch circuit consists of a
normally open
filter
pressure switch. The switch will open when the
pressure differential goes above the setting indicated
on the dial. When the pressure difference returns below
the setting on the dial, the switch will close.
Adjustment of dirty filter switch may be necessary to
ensure proper operation. See Figure 19 and Table 7 to
aid in setting the filter switch to operate at different
percentages of filter blockage.
AIRSTREAM BEFORE FILTER
TUBE LOCATED IN
COVER
REMOVE COVER
SCREW TO
TUBE LOCATED IN
AIRSTREAM AFTER FILTER
MIS-3901
ADJUSTMENT
INDICATOR ARROW
ADJUSTMENT
KNOB
FILTER
LIGHT
FIGURE 19
Dirty Filter Switch and Filter Indicator Light
MIS-3901
