60
Boiler Sequence of operation
NORMAL OPERATION
1.
The ESC Boilers are equipped with an
Intelligent Hydronic Control (control). This
control replaces the traditional separate
ignition control, high limit switch, blower
relay and circulator relay and adds energy
saving thermal purge features. Energy is
saved by starting the circulator and delaying
the burner start when there is residual heat
available in the boiler.
2.
The boiler’s sequence of operation is shown
in Table 4.
3
. When the thermostat calls for heat the
control starts the system circulator and
the thermal purge (circulator Pre-purge
time) begins. If the time is completed or
boiler temperature is less than the Start
Temperature (140°F default) the start
sequence continues by energizing the
blower. Once the pressure switch is proven,
the ignition sequence is started allowing gas
flow and ignition of the burners.
4.
If the thermostat is not satisfied and the
operating setpoint is reached the system
circulator will continue to operate and the
burner will stop. When the boiler water
temperature drops below the setpoint less
the differential setting the burner will restart.
5.
After the thermostat is satisfied the burner,
circulator and blower are stopped.
6.
When a indirect water heater aquastat call
for heat is wired to the DHW input the control
starts the Domestic Hot Water circulator
and, if the boiler temperature is less than
the operating setpoint less differential, the
blower is energized without delay. Once
the pressure switch is proven, the ignition
sequence is started allowing gas flow and
ignition of the burners.
BOILER FAULT
In the event the boiler fails to start, the control
provides status information to help determine
the cause of the problem. Table 5 provides
a list of boiler status codes that are reported.
Refer to the Troubleshooting Section for more
information.
APPENDIX H – OPERATION
Status Codes displayed in
STA
Mode
Status
STA
Description
Standby
(Burner off
Circulator off)
1
No call for heat detected
Circulator
Pre-purge
(burner off
circulator on)
1
Either condition is true:
a. Call for heat detected and boiler
temperature higher than
operating setpoint.
b. Call for heat detected and boiler
temperature higher than Start
Temperature (140°F default) and
Circulator Pre-purge Time has
not expired.
Self Test
17
Control internal checking
Waiting for
Pressure
Switch to Close
(Blower on)
3
The blower is turned on. The
control is waiting for the pressure
switch to close.
Pre-purge
4
The blower is run for a 30 second
pre-purge
Spark
6
The pilot fuel valve is open and
sparking is started.
Flame Proving
7
The main fuel valve is open and
flame is being proven.
Running
8
The burner runs until the call for
heat is satisfied or the operating
setpoint is reached.
Table 4: Sequence of Operation
Status Codes displayed in
STA
Mode
Status
STA
Description
Retry / Recycle
Delay
10
If the burner fails to light off (no
flame signal), it waits 5 minutes and
retries or if the control loses flame
signal during running, it will wait 10
seconds and then recycle.
Pressure
Switch Failed
to Open
11
The blower is off and the pressure
switch as failed to open.
Pressure
Switch Failed
to Close
12
The blower is on and the pressure
switch has failed to close.
Soft Lockout
13
System is shutdown and will restart
following a one hour enforced delay.
Hard Lockout
14
System is locked out. A manual or
power reset is required to be able to
light off again.
Limit Open
15
There is a call for heat from the
thermostat, but a Safety Limit is
open.
Flame
Present Out of
Sequence
16
Flame signal is still present when
expected to be 0 (no flame).
Table 5: Sequence Fault
Summary of Contents for ESC
Page 7: ...7 Figure S 1 Minimum Clearances to Combustibles SPECIFICATIONS continued...
Page 20: ...20 Figure 10 d Operating Instructions 10 Perform Startup Checks and Adjustments continued...
Page 37: ...37 Internal Wiring Figure IW 1 Wiring Diagram...
Page 38: ...38 Internal Wiring continued Figure IW 2 Wiring Diagram...