Operating instructions
31
14 - TROUBLESHOOTING - HIGH LIMIT CONTROL AND LWCO 
LED Legend and LWCO Test Button
1
 HI TEMP illuminates when boiler water temperature 
reaches high limit setting. Remains lit until water 
temperature falls 10°F below high limit setting. Limit 
prevents burner operation while this LED is on.
2
ACTIVE Indicates low water cut-off function is active. 
When control is installed with Electro-well, LED is on at all 
times when control is powered. If the control is installed 
with a well other than Electro-well, LED will not illuminate 
indicating the control is not providing low water cutoff 
functionality.
 WARNING
Burn and scald hazard. Do not add water until boiler 
has fully cooled. Failure to follow these instructions 
could result in death or serious injury.
! 
3
LOW WATER Illuminates if boiler is in low water 
condition. Control will prevent burner operation during this 
condition. 
Important: System must be checked by qualifi ed service 
agency prior to resuming operation.
4
ACTIVE Indicates that thermal targeting function is 
active and control reduces boiler temperature to conserve 
fuel. Economy feature is activated using the ECONOMY 
dial. 
5
TARGET  When feature is active, control continually 
sets target temperatures below high limit setting to 
maximize fuel effi ciency. When boiler reaches target 
temperature, LED illuminates and burner shuts down. 
Boiler water continues to circulate and heat the house as 
long as thermostat call continues. LED stays lit until boiler 
temperature drops below differential at which point boiler 
will be allowed to fi re again. 
Note: LED illuminates regularly during normal boiler 
operation.
6
PURGE Control is purging latent heat from boiler and 
will not fi re until temperature drops to 135°F. 
7
TEST/SETTING to Test LWCO: Press and hold TEST 
button. Red Low Water light will illuminate and burner 
circuit will de-energize.
Figure 20    - LED Legend










