LAARS EBP 175 MBTU/h - Installation, Operation and Maintenance Instructions - Manual (Page 31)

Endurance Page 31
Figure 35. Gas Valve.
SECTION 9
Servicing.
9.1 Sequence of Operation
Figures 32 and 33 depict the flow paths and
temperature sensor locations for the Laars Endurance.
During normal operation the boiler control will
display the supply temperature. The Endurance call for
heat may come from any of the following:
1. Heating call for heat (TT) from thermostat, end
switch, etc.
2. Domestic water call for heat from domestic water
flow switch.
3. Tank charge call for heat, when transfer tank is
less than 40°F (22°C) below the Off Point.
On a call for heat the following sequence will occur:
1. The anti-condensing valve is put in the proper
position.
2. The internal pump starts.
3. Blower pre-purge begins (7-seconds).
4. Boiler control sends the signal to the ignition
control that there is a call for heat.
5. After a self-check and 15 second ignition control
“pre-purge”, the ignition control begins the
ignitor warm-up period.
6. After the ignitor is warmed up, the gas valve
terminal on the ignition control is energized for
the 10-second trial for ignition.
7. 10 seconds after establishing combustion and
proof of flame (via the flame rod signal to
ground), the ignitor will be de-energized.
8. A gradual rise in temperature will be indicated
until the temperature approaches the Burner
Control Point. The firing rate will modulate based
on the rate of change in temperature as it seeks
the control point.
9 If, during a call for heat, the temperature reaches
the Burner Off Point, the Endurance combustion
will be de-energized, and will allow the
temperature to fall to the Burner On Point before
turning on again.
9.2.1 Fault Code Identification
The boiler control can display the following fault
codes:
• F1 = Boiler control internal error
• F3 = Gas valve status is on, with no call for
heat
• F4 = Supply sensor error
• F5 = Tank sensor error
• F6 = Return sensor error
• F8 = OAT sensor unreliable
• LO = Lockout
• OFF = Controller is off
• ICE = Low temperature protection
The boiler shows an alarm condition by flashing
the code and then showing the supply temperature.
All of the fault conditions shown on the boiler control
will prevent the Endurance from operating, with the
exception of F8. If the outside air temperature sensor is
found by the controller to be unreliable, the controller
will override the outdoor reset function, and will run
the Endurance in setpoint mode, instead of outdoor
reset mode.
The ignition control uses LED indication to
display the following fault codes:
• Steady On = Internal control failure
• 2 Flashes = Erroneous flame signal
• 3 Flashes = Ignition Control Lockout
9.2.2 Fault Correction
F-1 Switch off boiler and restart. If F-1 repeats,
replace boiler control.
F-3 In normal operation, the ignition control
sends a “gas valve energized” signal to
the boiler control, so the controller will be
able to time its PI algorithms correctly. An
F-3 fault code indicates that the ignition
control is sending a signal that the gas valve
has been energized, but there is no call for
heat. The boiler control will not allow the
Endurance to fire in this condition. This