54
PHTM II
Combi Installation, Operating & Service Instructions
110331-07 - 8/23
Status Screen Display
Description
Priority:
Standby
Status:
Standby
Burner -
Off
Pump(s) -
Off
Three Way Valve -
DHW
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
Three Way Valve -
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 and three way valve cycle
in sequence 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
Three Way Valve -
CH
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
Three Way Valve -
CH
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
Three Way Valve -
CH
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
Three Way Valve -
CH
After burner is started, a Calibration is initiated due to
1. Power Cycle 2. Periodic requirement
Calibration
: after blower reaches calibration speed setting, flame signal 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
Three Way Valve -
CH
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
Three Way Valve -
DHW
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
Three Way Valve -
Cycle
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
Three Way Valve -
Cycle
Hold status is entered when a delay is needed before allowing burner to fire. See user
display door label or section 19 Troubleshooting to determine cause of the Hold.
Priority:
Standby
Status:
Lockout
Burner -
Off
Pump(s) -
Off
Three Way Valve -
Cycle
A lockout status is entered to prevent boiler from running due to a detected problem. See
user display door label or section 19 Troubleshooting to determine cause of Lockout. Last
8 Lockouts are recorded in Lockout History.
Table 15-11: Boiler Sequence of Operation
15
Start-Up and Checkout
(continued)
Boiler Sequence of Operation
