UTICA BOILERS JE Installation Manual download pdf (Page 7)

Call For Heat

Control recognizes call for heat when power is applied

to 24V terminal on control module. Since control

receives signal from the thermostat, when call for heat is

terminated, heating cycle immediately terminates and all

control outputs will shut off.

Ignition Trial Period

Control energizes pilot gas valve and spark outputs for

ignition trial time of 12 seconds. If ame is sensed during

12 seconds of ignition trial, spark output is de-energized,

main gas valve is energized, and control enters steady heat

mode. If ame is not established within ignition trial period,

control de-energizes the spark and gas valve and operates

as described below in Ignition Failure/Re-try Sequence.

Ignition Failure/Re-Try Sequence

After an unsuccessful ignition trial, control checks to see

if maximum number of ignition trials (2 trials) has been

completed. If maximum number of ignition trials has been

completed, control will lockout. See Lockout (next page) for

details.

If maximum number of ignition trials has not been

completed, control delays for 5 minute inter-purge period.

After the inter-purge, control attempts another ignition

trial. Refer back to Ignition Trial Period for details.

Steady-State Heating

Control keeps pilot gas valve and main gas valve energized

while continuously monitoring call for heat and ame

status. Control will remain in this steady-state heating

mode until power is removed by (a) thermostat satised,

(b) pressure switch opening, or (c) ame being lost.

If call for heat is satised, power is removed from control,

de-energizing pilot gas valve and main gas valve.

If ame is lost, control will shut off main gas valve within

one second, leave pilot gas on, and immediately start

ignition trial. Control checks to see if maximum number

of ame losses (2 per call for heat) has been reached.

If maximum number of ame losses has been reached,

control locks out. See Lockout section for details.

PILOT

SEQUENCE OF OPERATION

1 2 3 4 5 6 7 8 9 10 11 12 ... 15 16

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UTICA BOILERS JE Installation Manual Page 7