Troubleshooting Table For Displayed Errors - A.O. Smith Theta T Series Installation, User And Service Manual

8.3

Troubleshooting table for displayed errors

Indication Cause
C05 (blocking error)
 Incorrect reference voltage
from the AD-converter.
Error message from the
EEPROM error

(Theta dual service/solar)
controller.
F18 (blocking error)
No supply voltage present on
(dual service/solar) control.
Communication error.
No communication cable
(correctly) connected or
damaged.
Short circuit Q/T-sensor.
F20 (blocking error)
DHW-pump not functioning.
(1/2)
Temperature of heating
system is to high.
Heating pump not functioning. 1. Check whether the (heating) pump is correctly (electrical)
Table continues on next page.
94
Installation-, User- and Service Manual
Measure
1. Reset controller.
2. Check that the frequency of the power supply is compliant
with 50 Hz ± 1 Hz. If not, contact your installation engineer
3. If the frequency is correct but the error persists, replace the
dual service/solar heating controller.
Check whether there is power to the controller. The measured
voltage must be 230 V (-15%, +10%).
AC
1. Check whether there is a (communication) cable between
the controller of the water heater and the controller of the
dual service module/solar heating system.
2. In case of no cable, a (communication) cable must be
connected.
3. In case of damage, the (communication) cable must be
replaced.
Check whether the Q/T-sensor is connected correctly to the
controller.
1. Disconnect the Q/T-sensor.
2. In case of no cable, a cable must be connected.
3. In case of damage, the cable must be replaced.
1. Check whether the (DHW) pump is correctly (electrical)
connected to the controller.
2. Check whether the (DHW) pump is correctly connected
hydraulically.
connected to the controller.
2. Check whether the (heating) pump is correctly connected
hydraulically.
Remark
- If the error persists, consult you installation
engineer.
- To replace the necessary parts, you must contact
your installation engineer.
- See electrical diagram (see Installation- User- and
Service manual of the water heater, 17 "Appen-
dices" or 11 "Appendices" of this manual).
- If the error persists, consult you installation
engineer.
- To replace the necessary parts, you must contact
your installation engineer.
See electrical diagram (11 "Appendices").
-
- To replace the necessary parts, you must contact
your installation engineer.