Crown Aruba 5 Installation Manual

34
only applies to the temperature displayed on the LED shown in Figure 11.0. Temperature units must be selected independently on
the displays of any control options plugged into Option Plugs 1 or 2.
bAc (Return to Status mode) - Exits adjustment mode. Any changes made to the parameters described above are saved, and
become eective, as soon as they are made; bAc only exits adjustment mode.
D. Sequence of Operation
(Refer to Figures 9.2 or 9.3 for Connection and Ladder diagrams)
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, ame roll-out switch, LWCO and any external limits connected to the Option Plug 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 ame 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 ows through the boiler to the ground connection on the S9361A. For
the ignition module to recognize that a pilot ame is present, the DC current owing 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.
TABLE 11.7 SUMMARY OF CIRCULATOR BEHAVIOR
Thermostat Inputs
Use of
“DHW”
Zone
Parameters Circulator Outputs
T-T “DHW”
2nd Zone
(dh)
DHW
Priority
(Pt)
Heating
(Red Circ. Lead)
“DHW”
(Blue Circ. Lead)
ON OFF DHW
dh=dh ON
ON OFF
OFF ON DHW
dh=dh ON
OFF ON
ON ON DHW
dh=dh ON
OFF ON
ON ON DHW
dh=dh OFF
ON ON
ON OFF DHW
dh=dh OFF
ON OFF
OFF ON DHW
dh=dh OFF
OFF ON
ON OFF Heat
dh=tt2 ON or OFF
ON OFF
OFF ON Heat
dh=tt2 ON or OFF
OFF ON
ON ON Heat
dh=tt2 ON or OFF
ON ON