LAARS SUMMIT SMW-250 - Install and Operating Manual - Manual (Page 26)

Page 26 LAARS Heating Systems
SECTION 8.
Trouble Shooting
8.1 Sequence of Operation
The SUMMIT appliance is a cold start appliance
that should start only on a call for heat from a tank
aquastat, room thermostat, zone valve end switch or
other space temperature control device. During normal
operation the Digital Display will indicate (on) if the
appliance is turned on and there is no call for heat.
When there is a call for heat the following sequence
will occur:
1. (a) The internal pump will start and the Digital
Display will indicate (---) for 5 seconds.
(b) After 5 seconds the blower prepurge cycle
will begin and continue for 6 seconds while
the Digital Display alternately indicates
(bFt) and (appliance discharge temperature
in °F)
2. Following the prepurge cycle the hot surface
ignitor will heat for 15 seconds while the blower
continues to operate.
3. The gas valve will then be energized and open
(green LED, marked GV on the PCB will light),
gas will flow and ignition will occur.
4. After ignition and proof of flame (via the flame
rod signal to ground), the ignitor will be
deenergized after 8 seconds and the burner will
modulate to high fire for maximum output.
5. The Digital Display should indicate a rapid rise
in temperature to 150°F (1-2 minute duration).
During this time, the mixing valve is positioned
to recirculate water internally from the supply to
the return to protect the boiler coil from
condensation. Note: Failure to reach 150°F in
the allotted time may be an indication of a
defective mixing valve thermostat and must be
corrected.
5. At 150°F the mixing valve will allow increased
flow to the system and a gradual rise in
temperature will exist until the temperature
approaches the setpoint temperature. At the
setpoint temperature, the input will start to
decrease until the limit temperature is reached or
the call for heat is satisfied. The input will be a
minimum at limit temperature. Note: The pump
will run for approximately 30 seconds after the
burner turns off.
8.2 Trouble Shooting - Fault Codes
The Summit appliance is controlled by a Pactrol
integrated control (PCB) which provides six fault
codes, with eight memories. To obtain previous fault
messages, press on the message center fault button
until the first fault code (FL1) is displayed. The last
recorded fault will appear e.g. F-4 (appliance
discharge thermistor faulty – open or shorted). The
control will then sequence through all eight memories,
indicating alternately the fault number and the fault
code (FL1, F-?; FL2, F-?; …; FL3, F-?). The fault
number in fault code FL1 is the most recent fault.
NOTE: If the Summit is in a lockout condition,
(LO appears on the display), then the problem is
not related to a fault code. See section 8.5 to resolve
problems when LO is displayed.
8.3 Fault Code Identification
The following six fault codes may be observed:
F-
Error corrected, control in auto reset period
(10 seconds)
F-0 No fault has occurred
F-1 Error occurred while reading fault logic of
main control
F-2 Over heat thermostat (appliance discharge
or Flue) has operated (open circuit)
F-3 Fan fault
F-4 Appliance discharge thermistor faulty
(open or short-circuited)
8.4 Fault Correction
(see also Fault Trees in this Section)
F-1 Switch off appliance and restart. If F-1
repeats, replace PCB
F-2 The overheat thermostat (safety limit)
opens at 245°F. Observe appliance
operation if the appliance shuts off before
the display indicates 245°F (107°C) replace
safety limit. If the temperature rises rapidly
and the safety limit operates, the internal
pump is not operating. Refer to the wiring
diagrams and check for voltage (120V)
across the terminals on the PCB marked PMP.
a. If there is no voltage, and the PCB display
does not indicate on or off, replace PCB.
b. If there is voltage, the pump or wiring is
defective.
The Flue Overheat Thermostat will also
create an F-2 error code because it is in
series with the safety limit. If the pump
checks out OK, check the Flue Overheat
thermostat for continuity. Replace if open
circuited.
F-3 Attempt to start the appliance. Check
combustion air blower operation. If F-3 is
indicated again, replace blower.
F-4 Check for damaged wiring or poor
connection at sensor plug. If they are OK
disconnect the sensor plug and check the
resistance across the sensor terminals. The