Viessmann WB2-44 - Replacement of Circuit Board VR20

Additional Information
61
Before replacing circuit board VR20, record actual system addresses (in particular coding addresses 000, 0B8, 042, 045,
015, 017, 0A2) and their corresponding values, heating curves and DHW settings.
Removing circuit board VR20
1. Loosen the two screws located
underneath the control
and
carefully fold down the control.
2. Unscrew and remove cover
.
3. Slide out circuit board VR20
using supplied handle.
Installing the replacement circuit board
1. Slide circuit board VR20
back into the control.
Ensure that circuit board is fully
plugged in and makes positive
contact.
2. Reinstall front enclosure panel and
cosmetic piping cover.
3. Verify that all coding addresses and
their values are programmed to
recorded actual/required values.
See table below.
4. Turn on power supply to boiler and
start up boiler.
Coding information
Please note!
This table does not reflect all necessary coding changes required for proper operation of the boiler.
See subsection “Overview of coding addresses” in this manual for other coding changes required.
Coding address
Possible coding values Required action
000: 000 (without DHW; factory default setting) Set according to system lay-
0
0
0
:
0
0
0
(
w
i
t
h
o
u
t
D
H
W
;
f
a
c
t
o
r
y
d
e
f
a
u
l
t
s
e
t
t
i
n
g
)
S
e
t
a
c
c
o
r
d
i
n
g
t
o
s
y
s
t
e
m
l
a
y
out. See page 52 for details.
015: 001(factory default setting) Do not change!
017: 001(factory default setting) Do not change!
0B8: 000 (no DHW storage tank)
001 (with DHW storage tank)
Set to (one of) the value(s)
indicated.
0
0
1
(
w
i
t
h
D
H
W
s
t
o
r
a
g
e
t
a
n
k
)
002 (with DHW storage tank optimized)
006 not assigned
i
n
d
i
c
a
t
e
d
.
5285 961 v1.3
Replacement of Circuit Board VR20
IMPORTANT