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if the blower prover does not activate after 15 seconds. This
time allows the blower relay to activate, the blower to come up
to speed, and the response from the blower prover to be filtered.
• User Settings Screen:
Each setpoint or user setting has either a limited selection of
values, or a limited range of values. The Up/Down keys are
used to change values. After changing an item, the Select key
is pressed to accept the change, or the Menu key is pressed to
reject the change and restore the item to its original value.
The following setpoints can be changed:
• Operating Setpoint:
This setpoint sets the base temperature for the control algorithm.
OPERATING SETPOINT ADJUSTMENT PROCEDURE
The system has a standard programmable Operating Setpoint
range of 70°F (21°C) to 190°F (88°C) for a VW and of 70°F
(21°C) to 220°F (104°C) for a VB for either a Remote or inlet
probe depending on selection. The user can easily change
the Operating Setpoint at any time by using the following
procedure. When any configuration or setpoint is changed
(and the Select key touched), the new value is IMMEDIATELY
saved to non-volatile memory. The factory default setting is
145°F (49°C).
1. Press the MENU key.
2. Scroll the ">" with the DOWN key next to the USER
SETTING SCREEN.
3. Press the SELECT key.
4. Scroll the ">" with the DOWN key until it is pointing to
OPERATING SETPOINT.
5. Press the SELECT key.
6. Use the UP or DOWN key to select the value you wish to enter.
7. Press the SELECT key to accept and store the new value.
• High Limit:
The outlet temperature probe contains both an ECO switch
and a thermistor for temperature measurement. The sensed
outlet temperature is used for the automatically resettable
High Limit setpoint. If the sensed outlet temperature exceeds
the High Limit setpoint, a "soft lockout" condition will occur and
the burner will be shut off. This fault condition is automatically
cleared when the temperature drops below the high limit
setpoint minus the high limit differential.
AUTO HIGH LIMIT SETPOINT ADJUSTMENT PROCEDURE/
OUTLET TEMPERATURE PROBE
The High Limit setpoint has a range of 90°F (32°C) to 210°F (99°C)
for a VW and a range of 90°F (32°C) to 235°F (113°C) for a VB.
Use the following procedure to change the automatically resettable
High Limit Setpoint:
1. Press the MENU key.
2. Scroll the ">" with the DOWN key next to USER SETTING SCREEN.
3. Press the SELECT key.
4. Scroll the ">" with the DOWN key until it is pointing to HIGH
LIMIT SETPOINT.
5. Press the SELECT KEY.
6. Use the UP and DOWN key to select the value you wish to enter.
7. Press the SELECT key to accept and store the new value.
• High Limit Differential:
The outlet temperature must be below the automatic High Limit
setpoint minus the High Limit Differential setpoint before a call
for heat can be generated.
HIGH LIMIT DIFFERENTIAL SETPOINT ADJUSTMENT
PROCEDURE
The High Limit Differential Setpoint has a range of 1°F to 50°F for
all models. Use the following procedure to change the High Limit
Differential Setpoint:
1. Press the MENU key.
2. Scroll the ">" with the down key next to USER SETTING SCREEN.
3. Press the SELECT key.
4. Scroll the ">" with the DOWN key until it is pointing to HIGH
LIMIT DIFFERENTIAL SETPOINT.
5. Press the SELECT key.
6. Use the UP or DOWN key to select the value you wish to enter.
7. Press the SELECT key to accept and store the new value.
• Operating Differential Setpoints:
Each of the two stages has an independent Operating
Differential setpoint.
• Temperature Units:
Temperature can be displayed in either °F or °C units.
• Post Circulate Delay Time:
The time circulation pump will stay on after the burner is
turned off. The time in seconds is adjustable with the
following values: 45, 90, 180 or continuous. If the
continuous value is selected the pump will remain on at
all times and the post circulate state time will be set at 45
seconds.
• Network Address:
This is a unique number assigned to this boiler to
differentiate it from other boilers or water heater on the same
A. O. Smith proprietary network. A valid Network Address
can be any number from 0 to 31. It is set by default to zero,
which is an invalid address. The boiler will not communicate
until it is changed to a valid and unique number. This prevents
two units from trying to respond to the same request from
the PC or supervisory network device.
• Configuration Settings Screen:
Displays the status of the dipswitches installed on all
boards as described earlier.
• Log & System Info Screen:
Displays the following information:
Elapsed hours of operation (Total time system has been
powered up)
Number of running minutes (Number of minutes system has
been in the run mode)