Post Purge; Lockout; High Temperature Limit Switch; Roll-Out Switch - York Sun Select YV28 Manual

If the call for heat (W1) is lost, the control de-
energizes the gas valve and begins post purge.
If low pressure switch opens, the control de-
energizes the gas valve and begins pressure switch
proving mode.
If flame is lost, the control de-energizes the gas
valve within 2.0 seconds and counts the flame loss.
If flame has been lost more than five times within
the same call for heat, the control locks out flashing
"5" on the LED. If flame has been lost less than
five times, the control attempts reignition after a
30 second inter-purge period.
High heat
The ICB recognizes a call for second stage heat
when W2 is energized. The control energizes the
high gas output.
If the call for second stage heat goes away and the
first stage call remains, the control de-energizes the
high gas valve and returns to low heat operation.
Response to loss of W1, low pressure switch, and
flame are identical to low heat operation.

Post Purge

The ICB runs the induced draft motor for a 5 second
post-purge period, then de-energizes the inducer. If
a call for heat occurs during post-purge, the control
finishes the post-purge, drops inducer out to re-
prove open pressure switch before continuing with
the heat cycle.

Lockout

While in lockout, the ICB keeps the main gas valve
and induced draft motor de-energized.
Lockouts due to failed ignition or flame losses
may be reset by removing the call for heat (W1)
for more than 1 second, but less than 20 seconds,
or by removing power from the control for over
0.25 seconds. The control will automatically reset
lockout after 60 minutes.
Lockouts due to detected internal control faults will
reset after 60 minutes or power interruption.

High temperature limit switch

If the high temperature limit switch is open the
control will run the inducer, de-energize the gas
valve, and flash "6" on the LED. When the high
temperature switch closes, the control will restart
the ignition sequence beginning with pre-purge.
If the high temperature limit is open for more than
6 minutes continuously during a call for heat, it is
assumed that the main blower has failed and the
control will enter a hard lockout and flash a "9"
on the LED. During the hard lockout, the control
86 Installation Manual: YORK Sun™ Select YV28 to YV50
®
Johnson Controls Ducted Systems
will continue to run the inducer as long as the limit
switch is open. If the limit switch recloses in this
hard lockout condition, the inducer will run a post
purge and then shutoff. The control will remain
locked out until power is removed and will not reset
automatically.

Roll-out switch

If the roll-out switch opens for more than
0.25 seconds, the ICB will run the inducer for a post-
purge period, immediately de-energize the gas
valve, and flash "7" on the LED.
If the roll-out switch closes, the control shall remain
locked out until power removed or "W" is removed.
Rollout switch lockout shall not reset automatically.

Power interruptions

Power interruptions less than 0.80 seconds shall
not cause the ICB to interrupt the heat sequence.
Power interruptions over 0.25 seconds will cause
the control reset lockout and ignition trial counters.
Power interruptions of any duration will not
cause lockout or any operation requiring manual
intervention.

Flame present with gas off

If flame is sensed for longer than 2.0 seconds during
a period when the gas valve should be closed, the
ICB will enter lockout. The control will turn on the
inducer blower while the flame is present.

Welded gas valve relay response

If either or both Main and Second Stage gas valve
outputs are sensed to be off for more than 1 second
when commanded to be ON, the ICB shuts off all
outputs and enters lockout.
If the Main valve output is sensed to be energized
for more than 1 second when commanded to be off,
the control de-energizes the induced draft motor
(if flame is not present) to attempt to open the
pressure switch to de-energize the gas valve. If the
Main gas valve is still sensed as energized after the
inducer has been off for 15 seconds, the control
re-energizes the inducer to attempt to vent the
unburned gas. In either case, the control locks out.