Laars boiler troubleshooting

Autonomous heating brings warmth and comfort to a home. A boiler is the ‘heart’ of such a system, and any fault occurring in it may impede or stop its work. Please, refer to the table below, find the cause of your problem and look for a solution.

Laars EBP0110 boilers troubleshooting

F1Boiler control internal error
F3Gas valve status is on, with no call for heat
F4Supply sensor error
F5Tank sensor error (EBP only)
F6Return sensor error
F8OAT sensor unreliable
OFFController is off
ICELow temperature protection
F-lSwitch off boiler and restart. If F-l repeats, replace boiler control.
F-3In 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 fault indicates that there is either something mis-wired on the boiler, or that the relay in this circuit has seized. Check the relay for seized contacts first, and if the relay is operational, check the wiring circuit on the boiler.
F-4Check 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 resistance of a good sensor is 10,000 ohms @ 77°F (25°C). Replace sensor if resistance is less than 500 or more than 20,000 ohms.
F-5Correct in the same manner as F-4.
F-8Check that the outdoor air sensor is installed properly, and that the wire and/or connection are not damaged. If okay, disconnect the sensor and check the resistance across the sensor terminals. The resistance of a good sensor is 10,000 ohms at 77°F (25°C). Replace sensor is resistance is less than 500 or more than 20,000 ohms.

Laars JVS boilers troubleshooting

1.Pump not operatingA. No powerA. Check circuit breakers and power source.
B. Pump defectiveB. Replace.
C. Incorrectly wiredC. Recheck wiring diagrams.
2.Pilot outageA. Inlet gas pressure too lowA. Consult gas utility company. Inlet gas pressure to boiler should be 5.5” to 10.5" water column on natural gas. 0.0" to 13.0" on propane gas.
B. Inlet gas pressure too high causing an unstable blowing pilotB. Pressure should be regulated within limits shown above.
C. Weak or defective thermocoupleC. Replace thermocouple.
D. Damaged pilot or thermocoupleD. Replace.
E. Dirty pilotE. Blow dust or lint out of pilot.
F. Plugged or undersized pilot orificeF. Clean or replace pilot orifice.
3.Flame roll-out on start-upA. Blocked flueA. Remove blockage.
B. Pilot out of position (delayed ignition)B. Correct pilot position.
C. Blocked heat exchanger or flueC. Clean and correct as necessary.
D. Refractory tile out of placeD. Correct or replace tile as necessary.
E. Altered draft diverterE. Install factory-provided draft diverter.
4.Spillage at draft hoodA. Cold chimneyA. Allow boiler to operate 5 minutes to create draft action.
B. Vent pipe pitches down to chimneyB. Reinstall vent pipe to pitch up from boiler to chimney.
C. Blocked chimneyC. Remove blockage.
D. Draft hood alteredD. Install factory-provided draft diverter.
E. Pre-fabricated chimney with incorrect capE. Install U.L. listed vent cap.
5.Flame has lazy yellow tipA. Low primary airA. Correct manifold pressure according to rating plate. Correct orifice size if necessary. Clean burner ports if dirty. Verify correct fuel type.
6.Not enough heatA. Inadequate gas supplyA. Gas meter too small. Gas line from meter to boiler too small.
B. Low manifold gas pressureB. Gas pressure on boiler manifold (at normal firing rate) should be adjusted to 4.0"W.C. natural gas, 9.0"W.C. propane.
C. Boiler size inadequateC. Replace with boiler of higher input.
D. JVS 100-225 only - Boiler not going to high fire.D. Check operation and setting of two-stage operating control.
7.Pump noisyA. Air in voluteA. Bleed air from volute. Check pump alignment.
B. Worn coupling or bearingsB. Replace worn parts.
8.Boiler pounding or knockingA. Too low water flow through boilerA. Check temperature rise between inlet and outlet boiler piping. 15°F to 25°F temperature rise is recommended. If temperature rise is over 25°F, increase pipe size or pump capacity or locate obstruction. Check for stuck closed zone valves.
Check for zone pumps not operating. Check for closed valve in system.

9.Boiler condensingA. Low water temperatureA. Flue product moisture will condense at the start-up until the boiler water temperature reaches the normal operating conditions.
10.Pump cavitates or low water pressure at boiler gauge or bubbles in system at high temperatureA. Defective fill valves or pressure regulatorA. Replace.
B. Oversized expansion tankB. Replace.
C. Expansion tank piped incorrectlyC. Repipe expansion tank to suction size of pump.
11.Pressure relief valve opensA. Water-logged expansion tankA. Drain 2/3of the water from the expansion tank.
12.Pilot is lit but main burners will not come onA. Gas valve not at "on" position (JVT)A. Turn knob to "on" position.
B. Boiler off on hi-limit controlB. Check for low water flow or hi-limit setting.
C. Boiler incorrectly wiredC.On single or multiple zone systems with zone valves, room thermostat should be wired to R & W terminals. For multiple zone systems with zone pumps, thermostats for extra zones should be wired to R & A terminals.
D. Boiler off on blocked vent switchD. Remedy as in symptom #4. Reset the manual reset switch.
E. Boiler off on flame roll-out switchE. Remedy as in symptom #3. Reset the manual reset switch.
F. Broken wire in thermostat circuit or defective thermostatF. Check continuity through thermostat circuit with wires disconnected from R & W.
G.JVS 100-225 Only - Two-stage operating control not functioning or loose contact.G.Check continuity and operation through two-stage operating control.
13.Boiler short cyclesA. Heat anticipator in room thermostat set too lowA. Increase setting (0.8 -1.0 is usually satisfactory).
B. Low water flow through boilerB. Increase size of pump or increase piping size.
C. Hi-limit switch may be set too lowC. Increase setting to at least 20°F over outlet water temperature.

Laars LMH boilers troubleshooting

27Internal errorFlame rod to groundCheck wiring / probe grounded, dirty probe
47Flame rod to ground leakageFaulty flame detectorClean or replace flame detector
4924VAC voltage low/highFaulty transformerCheck/correct supply line voltage; replace faulty transformer
52Motor tachometer faultFaulty fan / fan wiring fan circuitCheck fan harness wiring for continuity; replace faulty
53AC inputs phase reversedReverse 24V hot/neutral - use common ground
61Anti short cycleCall for heat will be held until timer resetsChange ASC timer setting
62Fan speed not provedDirty / defective fanClean or replace fan; check wiring
63LCI offSafety chain interruptCheck flow switch, aux high limit, LWCO, gas pressure switches, condensate level and correct problem
69Outlet high limitHigh limit trippedDetermine cause: low/no flow, valves closed, settings and correct
80DHW high limitCheck pump, time delay, valves closed, etc. And correct overtemp
81Delta T inlet/outlet limit
82Stack limitCould be caused by high ambient temperature, or high return water temperature
88Outlet T-rise limit
90Heat exchanger high limitDiagnose / repair cause of high temperature
91Inlet sensor fault
92Outlet sensor fault
93DHW sensor faultFaulty sensor or wiringCheck wiring / replace sensor; condition can be caused by short
95Stack sensor fault
96OAT temperature sensor fault temperature sensorFaulty outdoor air is open or shortedCheck wiring and sensor for short; replace sensor
105Flame detectedFlame exists at burner out of sequenceClean burner of soot or other debris that could when it should not be maintain flame
106Flame lost in MFEPUnstable flame during
107Flame lost early in Runlighting / flame proving equencesCheck venting, gas supply pressure, burner, fan, etc.
108Flame lost in Run
109Ignition failedProblem with ignitor, or other ignition-related deviceCheck / replace ignitor, wiring; check for shorting in ignitor cable
113Flame circuit timeoutFlame not established within expected time limitCheck all combustion components; purge gas; check ignition source
122Lightoff rate proving failed
123Purge rate proving failed
128Fan speed failed / prepurgeFan did not reach expected RPMCheck fan wiring; replace fan
129Fan speed failed / preignition
130Fan speed failed / ignition
131Fan movement detected during standbyFan should not be moving when not poweredCheck for common venting problems or otherwise forced air
132Fan speed failed during runFan lost or gained speed during run sequence away from control specFan overheating or otherwise failing; check cable; replace fan
137ILK failed to closeNo power at interlock ILKCheck J5 pin 1 for power - if no power, confirm safeties are closed
248CH outdoor temperature was invalid
251CH ODR max outdoor temp- erature setDoint was invalidConfirm outdoor reset settings. An invalid adjustment has been made
252CH ODR min outdoor temp- erature setpoint was invalid
253CH ODR min water temp- erature setpoint was invalid
254CH ODR temperature range was too small (min. 12°C / 22°F)Increase Outdoor air temp- erature min and max values to a difference greater than 22°F (12°C)Adjust setting to within appropriate range
255CH setpoint minus ODR min water temperature was too small (min. 12°C / 22°F) Increase setpoint or decrease min water temD.Increase Outdoor water temperature min and max values to a difference greater than 22°F (12°C)
565Heat exchanger T-rise limit was exceededHeat exchanger temperature rise exceedCheck for correct water flow