Laars Neotherm NTH, Installation And Operation Instruction Manual

Page: 91 / 104

Page 91
106 Flame lost in MFEP L 1. Check main valve wiring and operation -
correct any errors.
2. Check the fuel supply.
3. Check fuel pressure and repeat turndown
tests.
4. Check ignition transformer electrode, fl ame
detector, fl ame detector siting or fl ame rod
position.
5. If steps 1 through 4 are correct and the fault
persists, replace the module.
107 Flame lost early in run L
108 Flame lost in run L
109
Ignition failed L
110 Ignition failure occurred H Hold time of recycle and hold option. Will not
be a lockout fault. Hold Only. Internal hardware
test. Not a lockout.
111 Flame current lower than weak
threshold (min fl ame current
0.8mA).
H Hold time of recycle and hold option. Will not
be a lockout fault. Hold Only. Internal hardware
test. Not a lockout.
113 Flame circuit timeout L Flame sensed during Initiate or off cycle, hold
240 seconds, if present after 240 seconds,
system will lockout.
119
Control Interaction Fault H
Flap valve identifi cations confi gured incorrectly.
122 Lightoff rate proving failed L
1. Check wiring and correct any potential wiring
errors.
2. Check the VFDs (Variable-speed Fan Drive)
ability to change speeds.
3. Change the VFD
4. If the fault persists, replace the module.
123 Purge rate proving failed L
128 Fan speed failed during prepurge H or L
129
Fan speed failed during
preignition H or L
130 Fan speed failed during ignition H or L
131 Fan movement detected during
standby H
132 Fan speed failed during run H
137
ILK (Interlock) failed to close
H 1. Check wiring and correct any possible
shorts.
2. Check Interlock (ILK) switches to assure
proper function.
3. Verify voltage through the interlock string to
the interlock input with a voltmeter.
4. If steps 1-3 are correct and the fault persists,
replace the module.
149
Flame detected H or L
Holds if fl ame detected during Safe Start check
up to Flame Establishing period.
150 Flame not detected H Sequence returns to standby and restarts
sequence at the beginning of Purge after the
HF switch opens if fl ame detected during Safe
Start check up to Flame Establishing period.
154 Purge Fan switch On H or L 1. Purge fan switch is on when it should be off.
2. Check wiring and correct any errors.
3. Inspect the Purge Fan switch J6 terminal 3
and its connections. Make sure the switch
is working correctly and is not jumpered or
welded.
4. Reset and sequence the relay module.
5. If the fault persists, replace the relay module.
Code Description Lockout
or Hold
Procedure
N
EO
T
HERM
Commercial Boilers and Water Heaters