52
110328-02 - 6/22
ALTA
Installation, Operating & Service Instructions
Status Screen Display
Description
Priority:
Standby
Status:
Standby
Burner -
Off
Pump(s) -
Off
There is no call for heat, boiler is not firing and priority is "
standby
". Boiler is ready to
respond to a call for heat. Additionally, boiler and pumps remain off when Warm Weather
Shut Down is active or "Boiler Switch" (
A01
) is set to "Off".
Priority:
Standby
Status:
Pump Purge
Burner -
Off
Pump(s) -
Cycle
Pump Air Elimination (Pump Purge) is entered when power is cycled or when there has
been a supply high limit hold. During this state boiler pump cycles on and off every
5 seconds for two minutes to help remove air from boiler water piping. This may be
interrupted by pressing "
!
reset
" button.
Priority:
Central Heat
Status:
Standby
Burner -
Off
Pump(s) -
Cycle
Boiler is not firing. There is a CH demand and supply temperature is greater than setpoint
minus "Diff Below".
Priority:
Central Heat
Status:
Prepurge
Burner -
Off
Pump(s) -
On
When supply temperature drops, burner demand continues with following status shown:
Waiting For Limit To Close
: blower started, air pressure switch is checked.
Prepurge
: blower is driven to prepurge speed to empty chamber of flue products.
Priority:
Central Heat
Status:
Burner Ignition
Burner -
On
Pump(s) -
On
After prepurge is complete following status is shown:
Burner Ignition
: Spark and fuel valve are energized.
Priority:
Central Heat
Status:
Calibration
Burner -
On
Pump(s) -
On
After burner is started, a Calibration is initiated due to
1. Power Cycle 2. Periodic requirement
Calibration
: after blower reaches calibration speed setting, ionization setpoint is
calibrated, next blower drives to low fire and fuel valve output is calibrated (runs for 1
minute).
Priority:
Central Heat
Status:
Run
Burner -
On
Pump(s) -
On
After burner ignition (following calibration), the following status is shown:
Low Fire Hold
: modulation rate held at low fire to allow initial home heating
Run
(Modulate): Burner rate modulates to match home heat requirements.
Priority:
DHW
Status:
Run
Burner -
On
Pump(s) -
On
If CH demand is active and a DHW demand is received, DHW demand becomes "priority"
and modulation rate, setpoint, "Diff Above" and "Diff Below" are based on DHW settings.
Priority:
Standby
Status:
Post-purge
Burner -
Off
Pump(s) -
Off
If there is no call for heat, fuel valve is closed and blower is driven to post-purge speed to
empty combustion chamber of flue products.
Priority:
Standby
Status:
Hold
Burner -
Off
Pump(s) -
Off
Hold status is entered when a delay is needed before allowing burner to fire. See user
display door label or section 18 Troubleshooting to determine cause of the Hold.
Priority:
Standby
Status:
Lockout
Burner -
Off
Pump(s) -
Off
A lockout status is entered to prevent boiler from running due to a detected problem. See
user display door label or section 18 Troubleshooting to determine cause of Lockout. Last
8 Lockouts are recorded in Lockout History.
Table 14-10: Boiler Sequence of Operation
14
Start-Up and Checkout
(continued)
Boiler Sequence of Operation
