Honeywell C Boiler User Manual


 
L7224A,C; L7248A,C,L OIL AND ELECTRIC BOILER ELECTRONIC AQUASTAT
®
CONTROLLERS
11 68-0281—16
Fig. 9. L7224A,C multizone system with circulator connections.
Boiler is hot,
house is cold.
Display is ON. 120 Vac at C1-C2 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.
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.
If no 120 Vac, replace control.
If yes, check zone relays, circulators and
wiring.
ELL setting (L7248L only) Set ELL to Off for multizone system (see Fig.
11).
Set ELL to On for External Low Limit (see
Fig. 13).
Boiler above LL? If yes, check 120
Vac at ZR-L2 (only L7248L with
ELL set On)
If no 120 Vac, check C1-C2 (see above).
If yes, check the External Low Limit control.
Boiler is hot,
no hot potable
water.
Display is ON. Boiler Demand signal from the
water heater (either 120 Vac at
ZR-L2, or 0 Vac on T-T; depends
on installation and “duu” setting)
24 Vac on T-T (or 0 Vac on ZR-L2), check
wiring to water heater
Wiring OK, check the water heater
“duu” setting Set duu to ON if 120 Vac water heater
demand is connected to ZR
Set duu to OFF if open/closed water heater
demand is connected to T-T
Check DHW Module and DHW
Sensor
DHW Module not properly connected and/or
DHW Sensor improperly positioned
Table 11. Troubleshooting Guide
System
Condition
Diagnostic
Condition Check Action
M27115
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
1
CONTROL CASE MUST BE CONNECTED
TO EARTH GROUND. USE GROUNDING
SCREW PROVIDED.
2
C1
B1
ZC
L2
LINE
C2
ZR
L1
B2
T
T3
2
1
SENSOR
LINE
VOLTAGE
CIRCULATOR
LINE
VOLTAGE
OIL BURNER
RELAY
2
LOW
VOLTAGE
THERMOSTAT
L7224
3
L1
(HOT)
L2
1
2
1
4
5
6
ZONE 2
LOW VOLTAGE
THERMOSTAT
R845A RELAY ZONE 2
ZONE 2
CIRCULATOR
TO ADDITIONAL R845A
RELAYS FOR OTHER ZONES