L7224U OIL ELECTRONIC AQUASTAT
Table 3. L7224/L7248 Controller Operating Sequence.
Action
Thermostat
Circulator starts when water temperature is
calls for heat.
above Low Limit setting (if applicable).
Boiler temperature is checked. Burner
starts when water temperature is below
High Limit setting.
If Anti-short Cycle Time is enabled, the
burner does not start until the set Anti-
short Cycle Time between cycles expires
after the previous call for heat was
satisfied.
Boiler
Burner is turned off. Burner restarts when
temperature
the water temperature drops below the
exceeds the
High Limit setting minus the Differential.
High Limit.
Thermostat is
Circulator and burner turn off.
satisfied.
Boiler
Burner is turned on, Circulator is turned
temperature
off. Burner stops when the water
drops below
temperature exceeds the Low Limit
the Low Limit
setting.
setting minus
the
differential (if
applicable).
Error
If an error condition is detected, all outputs
conditions
except ZC are shut down. Burner is off.
1-5.
The controller continues to function and
restarts when error is corrected.
During the error check sequence, the
system checks for drift in the sensor and
corrosion in the connections.
Error
EnviraCOM communication is not
condition 6.
available.
Error
The controller has reset the High Limit,
condition 7.
Low Limit and Differential Setting to a
default setting and will continue to run at
those settings. Performance of the system
will be degraded.
Error
If the error condition is detected, all
condition 8.
outputs except ZC are shut down. Burner
is off.The controller continues to function
and restarts when all three user keys have
been pressed longer than 60 seconds.
Error
System continues to run with no outdoor
condition 9*.
reset functionality
Error
System continues to run with outdoor reset
condition 10*.
parameters enabled as programmed.
Error cleared automatically.
Error
System continues to run with boiler temp
condition 11*.
set to High Limit.
* Error condition only available when the Outdoor Reset
Module is installed.
69-1720EFS—01
®
CONTROLLER
System Response
Table 4. L7224 Controller Operating Sequence with
multiple zones connected through the ZR terminal
Action
Zone Request (ZR)
Boiler temperature is checked.
terminal is
Burner starts when water
connected to L1
temperature is below High Limit
(Zone calls for
setting. Anti Short-Cycle Time is
heat).
applied, see Table 3.
Boiler temperature
Burner is turned off. Burner restarts
exceeds the High
when the water temperature drops
Limit.
below the High Limit setting minus
the Differential.
Zone Request input
Burner turns off.
is de-energized
(Zones are
satisfied).
Boiler temperature
Burner turns on and Zone Control
drops below the
is de-energized. Burner turns off
Low Limit setting
and Zone Control is re-energized
minus the
when the water temperature
differential (if
exceeds the Low Limit setting.
applicable).
Table 5. Controller Operating Sequence with External
Low Limit device connected trough the ZR terminal.
Action
Zone Request (ZR)
Boiler temperature is checked.
terminal is
Burner starts when water
connected to L1
temperature is below High Limit
(External Low Limit
setting. Circulator turns off.
call for heat).
Boiler temperature
Burner is turned off. Burner restarts
exceeds the High
when the water temperature drops
Limit.
below the High Limit setting minus
the Differential.
Zone Request input
Burner is turned off.
is de-energized
(External Low Limit
is satisfied).
Table 6. L7224 Controller Operating Sequence with
Domestic Hot Water connected trough the ZR
Action
Zone Request (ZR)
terminal is connected to
L1 (Domestic Hot Water
calls for heat).
Boiler temperature
exceeds the High Limit.
Zone Request input is
de-energized (Domestic
Hot Water is satisfied).
8
System Response
System Response
terminal.
System Response
Boiler temperature is checked.
Burner starts when water
temperature is below High
Limit setting.
Burner is turned off. Burner
restarts when the water
temperature drops below the
High Limit setting minus the
Differential.
Burner is turned off.