Bosch WORCESTER Sense II, Installation Instructions Manual

Page: 49 / 64

49
Eliminate fault
Sense II – 6 720 818 367 (2015/10)
Fault code Sub- code
Cause or fault
description
Test procedure/Cause Corrective measure
A01 808 DHW heating: DHW
temp. sensor 1 faulty.
If the hot water
function is not
needed, deactivate it
on the controller
No hot water system installed Deactivate hot water system in the
service menu
Check connecting lead between controller and hot
water temperature sensor If there is a defect, replace the sensor
Check the electrical connection of the connecting
lead in the controller If a screw or plug is loose, rectify the
contact problem
Check the hot water temperature sensor
according to table (

page 7)
If values do not match, replace the
sensor
A01 809 DHW heating: DHW
temp. sensor 2 faulty.
If the hot water
function is not
needed, deactivate it
on the controller
No hot water system installed Deactivate hot water system in the
service menu
Check connecting lead between controller and hot
water temperature sensor If there is a defect, replace the sensor
Check the electrical connection of the connecting
lead in the controller If a screw or plug is loose, rectify the
contact problem
Check the hot water temperature sensor
according to table (

page 7)
If values do not match, replace the
sensor
A01 810 DHW stays cold Check if water is possibly being drawn from the
DHW cylinder constantly due to a leak or taps
being open If water is being drawn constantly,
take action to stop this
Check the position of the hot water temperature
sensor; it may be attached incorrectly or
suspended in the air Position the hot water temperature
sensor correctly
If the DHW priority was deselected and heating
and DHW are running in parallel, it is possible that
the boiler's output is not sufficient Set DHW to “priority”
Check whether the heating coil in the cylinder has
been completely vented Vent if necessary
Check the pipework between the heat source
(boiler) and cylinder, and with the aid of the
installation instructions, ensure that it is
connected properly Rectify any faults in the pipework
Using the technical documentation, check
whether the installed cylinder primary pump is
providing the required output Replace the pump if there are
deviations
Excessive losses in DHW circulation circuit Check DHW circulation circuit
Check the hot water temperature sensor
according to table (

page 7)
Replace the sensor if there are
deviations from the table values
Table 30 Fault displays