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Dirty Filter Switch
These units are equipped with a differential pressure
switch to indicate when the filter(s) needs to be
replaced. 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 2.2 to aid in setting
the filter switch to operate at different percentages of
filter blockage.
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. When the light is on, the filter needs to
be replaced. Once the filter(s) has been changed, the
indicator light will turn off.
Indoor Airflow Operation
Blower Speed Control
The blower is capable of changing speeds to best
match the requirements of the system depending on
which mode the system is in (see Table 2.1).
FIGURE 2.18
Verifying Freeze Switch Status
The unit will automatically switch to the required
speed for each mode. High sensible mode and
dehumidification mode are both communicated
separately from the LV. For more information on the
high sensible command from LV, please see the LV
manual.
Indoor Airflow Alarms
Blower Status Alarm
If the blower is commanded on and the fan status
switch (differential pressure) has not indicated the fan
is running within 45 seconds, the system will generate
an alarm.
This alarm is just a notification and will clear itself
when the conditions are no longer present.
To adjust the air flow alarm delay:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to
System Config
;
press ENTER key.
4. Press UP or DOWN keys to scroll to
Alarm Setup
(A8)
; press ENTER key.
5. Press ENTER key to scroll to
Air Flow Alarm Del
(see Figure 2.19).
6. Press UP or DOWN keys to change to the desired
value.
7. Press ENTER key to save the value.
Unit
Filter Blockage %
0%
10%
20%
30%
40%
50%
60%
70%
HR58APA
(Default) High S/T
Switch Static Setting
0.40
0.50
0.60
0.70
0.75
0.80
0.90
1.00
Evaporator Airflow %
100%
98.7% 98.1% 97.5% 91.7% 81.3% 79.1% 78.6%
HR58APA
Standard Airflow
Switch Static Setting
0.30
0.35
0.40
0.45
0.50
0.65
0.70
0.90
Evaporator Airflow %
100%
99.8%
99%
98.5% 96.8% 89.9%
84%
82.2%
All units tested equipped with MERV 8 filters. Appropriate supply (SG) and return (RG) grilles installed during testing. Pressure
switch adjustment may be necessary due to variations in filter type, installation and room pressure.
Bard recommends the filter switch be set at 50% filter blockage or less. Higher settings may significantly hinder unit
performance.
TABLE 2.2
Filter Switch Pressure Settings
FIGURE 2.19
Adjusting Air Flow Alarm Delay
