Page 46
Troubleshooting Flow Chart 2 – Burner Will Not Shut Down
NO
YES
YES
NO
NO
YES
YES
NO
NO
YES
Is the
Thermostat
(T-T) Calling
for Heat?
Is the
Indirect
(DHW) Calling
for Heat?
Is the
Red LED
(LOW WATER)
On?
The Control is
Sensing
Low Water.
TURN OFF POWER TO BURNER IMMEDIATELY!
CAUTION –ALWAYS ALLOW A BOILER TO FULLY COOL
BEFORE ADDING WATER.
Recheck wiring. Burner should never fire when
red or yellow LED’ are lit.
Is either
Yellow LED
On?
The Control has
Reached Target
or High Limit
Temperature.
The Control is
Operating
Normally.
The Control is
Operating
Normally.
The burner will continue to fire when there is a call
from the thermostat or external zone.
Replace Gas
Valve
Replace
Control.
When there is no call to fire the burner, the voltage
should be 0 VAC on the gas valve.
If valve allows any gas to pass without voltage going
to it, it needs to be replaced immediately.
Is there
24 VAC on
the Gas
Valve?
WARNING
11.D.2 Troubleshooting Flow Chart 2 (burners on)
from previous page
NO
Troubleshooting Flow Chart 1 – Burner Will Not Fire
CAUTION - ALWAYS ALLOW A BOILER
TO COOL BEFORE ADDING WATER
Is There
24 VAC on the
PV terminal of
the Valve?
If Flame Light is solid spark should be off and 24VAC
should be present at MV Terminal of the gas valve.
If not replace control.
If Flame light is on and 24VAC is present at MV Terminal
but there is still no main flame, Replace the Gas Valve.
If Flame Light is flashing, the board has stopped sparking
and is in a five minute pause, waiting before it resumes
trial for ignition. Flame is not being sensed. Could be
a no gas, bad pilot or bad control.
Check gas pressure to the pilot.
Clean or replace pilot orifice.
Check to ensure spark lead is in good
condition and not grounding.
Is the Pilot Lit?
Is the Flame
Light On?
Replace
Control
NO
NO
YES
YES
NO
NO
YES
YES
NO
YES
NO
NO
YES
NO
YES
YES
YES
NO
YES
NO
NO
NO
YES
YES
YES
Is the
Thermostat
Calling
for Heat?
Is the
Indirect
Calling
for Heat?
Is the
Red LED
(LOW WATER)
On?
The Control is
Sensing
Low Water.
Is the
Yellow LED
(HI TEMP)
On?
The Control is
Sensing High
Temperature.
The burner will not fire until the boiler water has dropped to the
high limit differential set-point (differential can be 10, 20, or 30F).
Check that the high temperature setting is correct (Should be set
between 180F and 220F).
Zone or boiler pump could be malfunctioning or system could
be air bound if boiler remains off without heat going to emitters.
Is the
Yellow LED
(TARGET)
On?
The Boiler has
Reached the
Target
Temperature.
When the ECONOMY function is active, the control monitors heating
demand and establishes Target boiler temperatures below the high
limit setting to conserve fuel.
The burner will not fire until the boiler temperature drops to the
automatically calculated Target Temp Differential.
Is the
Green LED
(TEMP ACTIVE)
On?
The Control is
Not Powered.
The Temp Active LED will be on at all times when the control is powered.
Check for 120 VAC on the control input.
Check for 24 VAC to the board.
The burner
will not fire unless there is
a call from the thermostat
or an external zone.
Set thermostat to call for
heat. Burner should fire.
The burner will not fire until the low water condition is satisfied.
Check that the system is filled with water.
Clean the interior of the well and the sensor bulb.
Ensure boiler is properly grounded.
Check that the sensor is inserted fully into the well and contact
between its spring clip and the copper well tube is made.
Ensure boiler pump is running and there is flow. If the boiler is hot
and not cooling down (and emitters are cold) there is likely a flow issue.
See Ignition
LED lights
Check the rollout switch, blocked vent switch, and
check terminals 5 & 6 (field interlock terminals).
Reset switches or correct field interlock problem.
Check vent damper, end switch, and check TB1, PV1 + PV4
should be closed by a jumper or a switch from an external
power vent kit or combustion air end switches.
Replace Control
Solid Light
Flashing Light
Is the Limit Light on?
V-Pwr light on?
V-SW light on?
Replace Control
Flashing Light
Is there spark
at the pilot?
Troubleshooting Flow
Chart 1 (burners off)
(continued)
LAARS Heating Systems
