Troubleshooting Guide - Honeywell L7224U Installation Instructions Manual

L7224U OIL ELECTRONIC AQUASTAT
System Condition
Boiler is cold, house Display is OFF.
is cold.
Display is ON.
TT-LED is OFF.
Display is ON.
TT-LED is OFF.
Display is ON.
TT-LED is ON.
B1 LED is ON.
Display is ON.
TT-LED is ON.
Boiler is hot, house Display is ON.
is cold. TT-LED is ON.
C1 LED is ON.
Display is ON.
TT-LED is ON.
C1 LED is OFF.
ZC LED is ON
Display is ON.
TT-LED is ON.
ZC LED is OFF
Boiler is hot, no hot
potable water
a
Refer to Fig. 7 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.
69-1720—03
®
CONTROLLER
Table 8. Troubleshooting Guide
Diagnostic Condition
b
.
c
.
a
.
Check
120 Vac system power.
24 Vac T-T.
24 V present; disconnect
thermostat, short T-T.
120 Vac at B1-B2.
Refer to Err on display.
120 Vac at C1-C2.
Boiler below the Low Limit
temperature, wait for boiler to
go above Low Limit
temperature.
Boiler above LL? If yes, check
for 120 Vac between ZC and
L2.
10
Action
Turn system power on.
No 24 V; replace controller.
Boiler starts, check wiring and
thermostat.
• If no, replace controller.
• If yes, check burner and
wiring.
—
• 120 Vac at C1-C2, check
wiring to pump.
• Wiring ok, is pump running?
If not, replace the pump.
• If pump is running, check for
trapped air or closed zone
valves.
—
• If no 120 Vac, replace
controller.
• If yes, check zone relays,
circulators and wiring.
•