The Bus connection of clamps M and O are used
to manage the boilers in cascade.
The jumper X40 must be eliminated whenever
the room thermostat or cascade regulator is
connected.
3.2 WIRING DIAGRAM.
Fig. 3-2
Ke
y:
B1
-
Fl
ow p
ro
be
B2
-
D
HW p
ro
be (o
pt
io
na
l)
B4
-
Ext
er
na
l t
em
per
at
ur
e p
ro
be (o
pt
io
na
l)
B5
-
Re
tu
rn p
ro
be
B10
-
Fl
ue p
ro
be
E1
-
Ig
ni
tio
n e
lec
tro
de
E2
-
D
et
ec
tio
n e
lec
tro
de
E4
-
Sa
fety t
her
m
os
ta
t
M1
-
Bo
iler p
um
p
M20
-
Fa
n
M30
-
3-w
ay v
al
ve (o
pt
io
na
l)
S1
-
M
ai
n s
w
itc
h
S5
-
Sys
tem p
re
ssu
re s
w
itc
h m
icr
o s
w
itc
h
S16
-
Su
m
m
er s
w
itc
h (n
ot s
up
pl
ied b
y I
m
m
er
gas)
S20
-
O
N/O
FF r
oo
m t
her
m
os
ta
t (o
pt
io
na
l)
T10
-
Lo
w v
ol
ta
ge t
ra
ns
fo
rm
er
X40
-
Ro
om t
her
m
os
ta
t j
um
per
Y1
-
G
as v
al
ve (24 V
ra
c)
1
-
D
isp
la
y b
oa
rd
2
-
An
al. I
np
ut
3
-
230 V
ac 50 H
z
4
-
Ext
er
na
l P
um
p M
ax. 1 A
5
-
Fu
se
6
-
Br
ow
n
7
-
Bl
ue
8
-
Ye
llo
w/G
re
en
9
-
Bl
ac
k
10
-
Gr
ey
11
-
O
ra
nge
12
-
W
hi
te B
ro
w
n
13
-
W
hi
te
14
-
Pu
rp
le
15
-
W
hi
te b
lu
16
-
Re
d
17
-
D
om
es
tic h
ot w
at
er
18
-
CH
For safety reasons the P.C.B. envisions a fuse
that cannot be restored in series with the electric
power supply of the gas valve.
12
1
6
7
11
9
13
14
15
10
16
9
6
9
16
6
7
14
10
11
9
16
9
13
16
9
15
12
12
18
17
13
9
16
10
9
10
5
6
7
8
9
10
3
4
2
8
6
7
8
6
7
14
13
14
13
13
16
10
10
134
TR
SI
RU
IE
CZ
