3 69-1957—1
L7224 SERIES
Table 2. L7224 Controller Operating Sequence
Troubleshooting
When attempting to diagnose system performance, reference the
LED display to help identify specific areas not working properly.
The LED display will scroll “err”, followed by a digit (1-8). See
Table 1 for a description of the error and suggested actions. See
below for a troubleshooting guide.
Action System Response
Thermostat
calls for heat.
Circulator starts when water temperature is
above Low Limit setting (if applicable). Boiler
temperature is checked. Burner starts when
water temperature is below High Limit setting.
Boiler exceeds
the High Limit.
Burner is turned off. Burner restarts when the
water temperature drops below the High Limit
setting minus the differential.
Thermostat is
satisfied.
Circulator and burner turn off.
Error conditions
1-5.
If an error condition is detected, all outputs
except ZC are shut down. Burner is off. Control
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 conditions
6-7.
If error condition 6 or 7 occurs, the control has
reset the High Limit, 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 condition
8.
If the error condition is detected, all outputs
except ZC are shut down. Burner is off. Control
continues to function and restarts when all three
user keys have been pressed longer than 60
seconds.
Table 3. Troubleshooting Guidea.
System
Condition
Diagnostic
Condition Check Action
Boiler is
cold,
house is
cold
Display is OFF 120 Vac system
power.
Turn system power on.
Display is ON;
TT-LED is OFF
24 Vac T-T No 24V; replace
control
Display is ON;
TT-LED is OFF
24V present;
disconnect
thermostat,
short T-T
Boiler starts, check
wiring and thermostat
a. Refer to Fig. 5 for Display and LED locations.
b. ZC LED ON indicates ZC terminal power is OFF.
c. ZC LED OFF indicates ZC terminal power is ON.
69-1957-1.fm Page 3 Tuesday, June 20, 2006 11:06 AM
