Utica Boilers UB90-200 Installation Instruction

POWER ON 

STAND BY

THERMOSTAT

CALLS FOR HEAT

CIRCULATOR

ENERGIZES THRU

2K1 CONTACTS

IBC SELFCHECK OF 

INTERNAL CIRCUITRY

1-2 SEC

IBC 

CHECKS 

N.O. AIR

PRESSURE

SWITCH

CONTACTS

FALSE 

POSITIVE 

PROOF OF 

AIRFLOW. IBC WAITS 

FOR 45 SEC 

FOR AIR PRESSURE 

SWITCH CONTACTS 

TO OPEN

CLOSED

CLOSED

DRAFT INDUCER

ENERGIZES THRU

1K1 CONTACTS

OPEN

IBC 

WAITS FOR 

UP TO  5 MINUTES 

FOR AIR PRESSURE 

SWITCH CONTACTS TO CLOSE

INDICATING FAN 

SUCTION 

PRESENT

CLOSED

CONTROL LOCKOUT. 

BLINKS. RESET REQUIRED.  CIRCULATOR 

REMAINS ENERGIZED AS LONG AS 

THERMOSTAT CONTINURES TO CALL FOR 

HEAT

OPEN

   AIRFLOW PROVED.

DRAFT INDUCER RUNS FOR 15 SEC PREPURGE

OPEN

PURGE LIGHT GOES OUT. HOT SURFACE IGNITER 

POWERED THRU 5K1 5K2 CONTACTS FOR 20 

SEC IGNITER WARMUP. BRIGHT YELLOW 

ORANGE GLOW OF THE HOT SURFACE IGNITER 

CAN BE OBSERVED THRU THE OBSERVATION 

PORT IN FRONT OF BOILER SECTION JUST 

ABOVE IGNITER,

GAS VALVE ENERGIZED THRU 3K1 AND 4K1.

CONTACTS, 

GAS VALVE OPENS FOR 5 SEC TRIAL FOR 

IGNITION. BLUE ORANGE GLOW OF THE BURNER 

CAN BE SEEN THRU OBSERVATION PORT.

2 SEC INTO THE 5 SEC IGNITION TRIAL. POWER 

IS TURNED OFF TO THE HOT SURFACE IGNITER. 

DURING THE LAST 2 SEC OF THE 5 SEC IGNITION 

TRIAL MAIN BURNER FLAME IS PROVED BY FLAME 

RECTIFICATION A  FLAME SIGNAL TO IBC. GAS VALVE 

REMAINS ENERGIZED. BOILER RUNS.

DOES 

MAIN 

BURNER PROVE 

FLAME WITHIN INITIAL 

TRIAL FOR 

IGNITION 

PERIOD?

CONTROL WILL ATTEMPT 2 

ADDITTIONAL IGNITION SEQUENCES.

STARTING WITH PREPURGE.

IF MAIN BURNER DOES NOT PROVE 

FLAME IN 3 TRIALS, CONTROL 

LOCKOUT. 

VALVE/FLAME LIGHT BLINKS, 

RESET IS REQUIRED. THIS PROBLEM IS A 

RESULT OF NOT ESTABLISHING FLAME SIGNAL.

NORMAL 

OPERATION

YES

NO