Differential Airflow Switch; Filters; Dirty Filter Switch; Dirty Filter Alarm - Bard FUSION-TEC HR36APA Service Instructions Manual

FIGURE 17
Adjusting Air Flow Alarm Delay

Differential Airflow Switch

The unit is equipped with a differential pressure airflow
switch to monitor the blower (see Figure 18). If the
blower is turned on and the switch doesn't close to
indicate there is differential pressure between the inlet
and outlet of the blower, an alarm will be generated.
For switch settings, see Figure 18.
FIGURE 18
Dirty Filter Switch and Blower Status Switch
Differential airflow status can be viewed by:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
TECHNICIAN password 1313.
3. Press UP or DOWN keys to scroll to I/O Config;
press ENTER key.
4. Press UP or DOWN keys to scroll to Digital In
Config (C2); press ENTER key.
5. Reference 7 NoAir row and Val column (see Figure
19).
Manual 2100-670B
Page 16 of 33
FIGURE 19
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 18). 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 Table 7 and Figure 20 to
aid in setting the filter switch to operate at different
percentages of filter blockage.

Dirty Filter Alarm

The wall unit is equipped with a differential pressure
switch input to the controller. When the switch
indicates a dirty filter, the controller will generate an
alarm. Once the condition is no longer present, the
alarm will automatically clear. Additionally, an indicator
light will be turned on with the alarm and turned off
when the alarm clears.
The threshold of this alarm is adjusted by changing the
settings on the switch (see Table 7).

Filter Indicator Light

These units are equipped with a 24v indicator light
mounted on side of unit that displays the current status
of the filter (see Figure 20). When the light is on, the
filter needs to be replaced. Once the filter(s) has been
changed, the indicator light will turn off.