Crown Boiler AWR Series Installation Instructions Manual page 38

Thermostat Inputs
T-T "DHW"
ON OFF
OFF ON
ON ON
ON ON
ON OFF
OFF ON
ON OFF
OFF ON
ON ON
bAc (Return to Status mode) - Exits adjustment mode. Any changes made to the parameters described above are saved, and
become effective, as soon as they are made; bAc only exits adjustment mode.
1) When the boiler is energized, 24 volts is immediately applied to terminals 1 (blue) and 4 (yellow) on the vent damper.
Assuming that there is no call for heat, and that the damper switch is in the "automatic" position, the damper will close.
2) A call for heat from the thermostat connected to T-T energizes the Heating Circulator (connected to red and white leads in
J-box).
3) Depending on the boiler water temperature at the time of the call for heat, the control will do one of two things:
• If the water temperature is below the thermal purge start temperature (St), the control will continue the ignition se-
quence.
• If the boiler water temperature is above the thermal purge start temperature, the boiler will wait until either of the follow-
ing conditions are met before continuing the ignition sequence:
a) The boiler water temperature falls below the thermal purge start temperature (St) Factory default is 140F.
b) The thermal purge time elapses (PP). Factory default is 2 minutes.
4) If the blocked vent switch, flame roll-out switch, LWCO and any external limits are made, 24 VAC will be applied across pin
terminal 2 (orange) and 4 (yellow) at the vent damper and the damper will open.
5) Once the vent damper is fully open, an end switch inside the damper will make, energizing pin 3 (red) at the damper. The
control reads 24VAC between this pin and pin 4 (yellow) as proof that the damper has opened.
6) The control waits for a 1.7s "prepurge period" to pass before attempting to light the pilot.
7) The control starts an ignition spark at the pilot and applies 24 volts across the pilot valve (terminals PV and MV/PV on the
gas valve).
8) Once the pilot is established, the pilot flame will act as a diode, converting the AC current at the electrode to a half wave DC
current at the pilot's ground strap. This DC current flows through the boiler to the ground connection on the S9361A. For
the ignition module to recognize that a pilot flame is present, the DC current flowing into this terminal must be in excess of
approximately 1.0 uA.
9) If the pilot is not proven within 90 seconds of the beginning of the trial for ignition, the pilot valve will close and wait 5 min-
utes before the ignition sequence is retried.
10) Once the ignition module detects the presence of a pilot flame, voltage is applied across the main valve (terminals MV and
MV/PV on the valve), opening the valve and establishing main flame.
11) If the water temperature climbs above the high limit setting during the call for heat, the burner will shut down, and the vent
TABLE 11.7 SUMMARY OF CIRCULATOR BEHAVIOR
Parameters
Use of
"DHW" 2nd Zone
Zone (dh)
DHW dh=dh
DHW
dh=dh
DHW dh=dh
DHW dh=dh
DHW dh=dh
DHW dh=dh
Heat dh=tt2
Heat dh=tt2
Heat dh=tt2
D. Sequence of Operation
(Refer to Figures 9.3 or 9.4 for Connection and Ladder diagrams)
Circulator Outputs
DHW
Priority Heating
(Pt) (Red Circ. Lead)
ON
ON
OFF
ON
OFF
ON
ON
OFF
ON
OFF
OFF
OFF
ON or OFF ON
ON or OFF OFF
ON or OFF ON
38
"DHW"
(Blue Circ. Lead)
OFF
ON
ON
ON
OFF
ON
OFF
ON
ON