Blower Status Switch; Blower Status Alarm; Filters; Dirty Filter Switch - Bard MEGA-TEC W090A Service Instructions Manual

TABLE 6
Indoor Blower Performance
ESP
(Inch H
W090A 0.25
W120A 0.30
W150A 0.35
TABLE 7
Maximum ESP of Operation
Electric Heat Only
Model
-B0Z
-B09
-B18
-C0Z
-C09
-C18
* Unit is rated for free blow non-ducted operation with
SG-10W Supply Grille and RG-10W Return Grille.

Blower Status Switch

The unit is equipped with a differential pressure airflow
switch to monitor the blower (see Figure 24). 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 24.
FIGURE 24
Dirty Filter Switch and Blower Status Switch

Dirty Filter Switch

(W090 Set @ 1.00)
(W120 Set @ 1.40)
(W150 Set @ 1.20)
Dry Wet
0) Coil Coil
2
2980 2850
4160 3890
4730 4580
Static Pressure ("WC)*
.50"
.50"
.50"
.50"
.50"
.50"
Blower Status Switch
(W090 Set @ 0.40)
(W120 Set @ 0.80)
(W150 Set @ 0.40)
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 Inputs;
press ENTER key.
5. Reference AIrflw 1 row and Val column (see Figure
25).
FIGURE 25
Verifying Differential Airflow Status

Blower Status Alarm

When the blower is on for 45 seconds and no airflow
is detected by the airflow switch, the compressor
and heating operations will be disabled. The system
will wait 5 minutes before trying again. After three
consecutive no airflow events, the system will generate
an alarm and lockout requiring a user reset.

Filters

The unit is equipped with four (4) 20" x 24" x 2" MERV 8
filters (two per coil). The filters lift and slide into position
making them easy to service. The filters can be serviced
by opening the "hinged" front access panel and locking it
into position. Then lift and slide into position as needed.
Dirty Filter Switch
These units are equipped with a differential pressure
switch to indicate when the filter(s) needs to be
replaced (see Figure 24). The dirty filter switch
measures the pressure difference across the filter
through silicone tubing routed to the blower and
evaporator 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 26 to aid in setting
the filter switch to operate at different percentages of
filter blockage.
Manual 2100-671C
Page 19 of 59