LAARS Heating Systems
Page 110
SECTION 12 Troubleshooting
Condition
Information
Corrective Action
Flow Switch
•
Insufficient flow at the outlet of the
boiler/heater
•
Auto-reset Condition
•
Annunciation – “Warning Flow switch open”
on Message Screen
•
Faulty boiler/heater pump – replace pump.
•
Faulty pump contactor – replace contactor.
•
Blown boiler/heater pump fuse – replace fuse F14 on the
control board.
Low Water
Cut Off
•
Insufficient water level in the boiler/heater
heat exchanger.
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Reset the LWCO from the reset button on the LWCO module.
•
Verify the system is full of water and all air has been purged
from the system.
•
Check for loose jumpers if the LWCO is not installed.
Manual
Reset High
Limit
•
Outlet water temperature has exceeded the
manual reset high limit setting
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Verify the system is full of water and all air has been purged
from the system.
•
Verify the boiler/heater is piped properly into the heating
system.
•
Check for proper pump operations.
•
Check the manual reset high limit set point.
Auto Reset
High Limit
•
Outlet water temperature has exceeded the
auto reset high limit setting
•
Auto-reset Condition
•
Annunciation – “Warning High limit auto
error” on Message Screen
•
Verify the system is full of water and all air has been purged
from the system.
•
Verify the boiler/heater is piped properly into the heating
system.
•
Check for proper pump operations.
•
Check the manual reset high limit set point.
Pressure
Switch
•
Blocked flue switch contacts are open
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Check the wiring connections to the switch. The wires should
be connected to the common and normally open terminals.
•
Check reference hose and tubing connected to the pressure
switch for blockage/obstruction.
•
Faulty switch – replace switch.
•
Verify blower is operating – replace if necessary.
High Gas
Pressure
•
The high gas pressure switch has tripped
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Refer to Section 3 for Gas Supply and Piping information.
•
Verify supply and manifold gas pressures satisfy installation
requirements.
Low Gas
Pressure
•
The low gas pressure switch has tripped
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Refer to Section 3 for Gas Supply and Piping information.
•
Verify supply and manifold gas pressures satisfy installation
requirements.
Condensate
Level
•
Condensate trap water level is high
•
Auto-reset Condition
•
Annunciation – “Warning Condensate level”
on Message screen
•
Check condensate trap for proper drainage
•
Check condensate trap for stuck level switch
Outlet
Sensor
•
Outlet probe is not connected
•
Manual-reset Condition
•
Annunciation – on Navigation Bar
•
Check the sensor and wiring. Repair or replace as needed.
•
The outlet probe is a dual element probe with 10K and 20K
thermistors. A quick test is to measure resistance and verify
one resistance is double the other. Replace if necessary.
•
Measure the resistance of each element of the sensor and
compare to the resistance table below. Replace if necessary.
Temp (°F)
10K
20K
Resistance (Ω)
Resistance (Ω)
68
12555
25099
86
8025
16057
104
5279
10569
122
3563
7139
140
2463
4937
158
1739
3489
176
1253
2514
194
919
1845
212
685
1376
Lockout: Low Water Cut Off
Lockout: Man Reset High Limit
Lockout: Burner APS Switch
Lockout: High Gas Pressure
Lockout: Low Gas Pressure
Lockout: Outlet Probe
