L.B. White Guardian with Smart Sense - Spark Ignition (60K / 100K) - Manual (Page 21)

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OPERATION SEQUENCE:
— A call for heat occurs from the building controller.
— 115 VAC is sent to:
-- 40 VA transformer and to ignition control
-- 20 VA transformer
— 20 VA transformer reduces line voltage to 24 VAC.
-- 24 VAC is sent to operate signal conditioner
— 0-10 VDC, 0-20 mA, or 4-20 mA signal is sent to
signal conditioner from building controller.
— Signal conditioner changes the building controller input
signal to 0-15 VDC which is sent to variable rate gas
control valve.
— 40 VA transformer reduces line voltage to 24 VAC
-- 24 V.A.C. is sent from transformer to the ignition
control.
— Red light on ignition control is illuminated
— Ignition control module performs an internal safe start
check
-- Internal components are tested
-- Amperage is sent to flame sensor from ignition
control to start flame proving process.
-- Ignition control terminal PS1 sends 24 VAC to air
proving switch.
— Ignition control module begins safety lockout timing
— Ignition control module sends 115 VAC from terminal
IND to the fan motor.
-- Fan motor starts
-- Air proving switch closes and 24 VAC is returned
to ignition control terminal PS2.
— Ignition control sends power to the igniter.
-- Igniter sparks.
— Ignition control sends 24 VAC from terminal MV to the
gas control valve through the high limit switch.
— Ignition occurs.
-- Igniter sparks until flame proving occurs.
— Ignition control shuts off igniter spark.
-- Gas valve stays open
The Smart Sense
™ control logic incorporated in the building
controller then manages the output of the Smart Sense
™
heater as necessary to achieve and maintain the desired room
temperature.
Note: When properly set up, the Smart Sense
™
variable rate heater will run for long periods of
time - much longer than typically experienced
with on/off heating. This is normal and is key to
achieving the consistent air temperatures and
fuel savings associated with
Smart Sense
™
variable rate heating.
If the building controller determines that heat is no longer
required, it will shut the heater off and then will initiate the
heating sequence again when heat is required.
MULTIPLE IGNITION TRIAL SEQUENCE:
— First trial for ignition takes approximately 10 seconds
— Two more trials for ignition will occur
-- Second and third trials follow immediately if first trial
fails.
-- Module starts a 15 minute waiting period to allow
ignition Interruption to pass
-- Ignition control repeats 3 ignition attempts after 15
minute wait period.
— If ignition control does not prove flame, the control goes
into safety lockout (3 Flash Pattern)
-- Igniter shuts down
-- Fan motor stops
-- Gas valve closes
— Ignition control must be reset
-- Unplug the heater and plug it back in
-- OR --
-- Turn building controller off and then back on to call
for heat.