Filter
Top Products
Hydronic Heating Boilers and
Domestic Water Heaters
68
LADDER DIAGRAM 990,000 - 2,070,000 BTU/HR MODELS
24 VAC
CONTROL
J3
5
4
6
1
2
3
O.C .
J1
J2
3
2
1
J4
P
O
N
C
BR
/
W
ALARM INPUTS
1, 2, 3 & 4
JOIN HERE
S2/FS
F2
F
1
L
I
N
E
S
1
O/W
P
RESSURE
SWIT
CH
#
2
R
ESE
T
P
U
R
G
E
Y
P
T
/W
S
2
/
F
S
-
+
F2
F1
N
EU
L
INE
S
1
O
G
R
PRESSURE
SWITCH #1
R
ESE
T
P
U
R
G
E
GY
GY
PUMP RELAY
B
K
BK
S
T
AG
E #
2
B
L
OWER #
1
W
W
W
Y
~~~~
~~~~
S
T
AGE
#
1
1
61
5
1817
2
2
21
2
0
19
H
EAT
DEM
#
1
E
L
E
C
TRONIC
T
EMPE
RATURE
C
ONTROLL
E
R
O
PT
IONA
L
RUN TIME
RELAY
C
ONTAC
T
S
LBL20012 REV A
24 VAC
1224
23
120 VAC
1
141
3
+
-
HD-
Y
Y
W
CHASSIS
GROUND
-
INTE
R
MIT
T
E
NT
ALARM EN
ABL
E
R
E
LAY
Y
Y
2
NO2C
4NO
4C
1
NO1
C
3NO3
C
BK
BK
R
R
B
K/W
G
W
Y
O
P
TIO
NAL
C
ONTACTS
ANY FA
ILURE
IGNIT
E
R
T
RIAL
G
Y
GY
BK
P
BL
O
O
O/W
O/
W
R/O
B
L
B
R
B
R
BK
G
NEU
W
W
CIRCUIT BREAKER
BL
+
ALARM
CONTACTS
OPTIONAL ALARM
BELL 24V OUTPUT
SILENCE
BL
ALARM
G
BL
Y
C1
C
2
N
O
1
N
O
2
P
R
OVING
R
E
L
A
Y
C
1
NO1
A1 B1
A
2
A3 B2 B3
C
O
NTI
NUO
US IN
T
E
R
M
ITT
E
N
T
FLOW
SWIT
CH
O
STATUS
Y
CHASSIS
GR
OUND
CHASSIS
GROUND
S
ENSORS
I
G
NITE
R
TRIAL
G
Y/
W
HI-LIMIT
AUX. HI-LIMIT
PR
ALARM
INPUT 4
BK
1
2
BK
LA
R
T
U
ENE
NIL
GROUND
BL
A
L
AR
M
I
N
PUT 3
O
/
BK
BR
BL
PR/
B
K
BL
PR/BK
S
T
A
GE
#1
ST
A
GE #4
S
T
AGE #
3
BL
O
WER #2
Y
Y
Y
Y
W
W
W
Y
R
R
/O
R/O
R/BK
R/W
BL
R
120 VAC 15AMPS
60Hz
O/BK
R
/
BK
R/
W
BL
Y
P
R
P
R
Y
PR
BK/
W
B
R/W
BR
/W
BR
B
R
W
PR
P
R
T
PR/BK
P
R
/
B
K
BR/W
BR/
W
B
R
/
W
P
R
/B
K
P
R
/B
K
B
R
/
W
Y
Y
P
ROVI
N
G
SWITCH
MO
T
OR
CONTAC
T
S
W
BK/
W
BK/
W
W
B
R
T
T
B
R
B
R
ON/OFF
POWER
SWITCH
PR
R
/
O
L
O
U
V
E
R
/
V
E
N
T
E
R
E
NAB
L
E
/
CON
T
ACT
R
E
L
A
Y
F
IEL
D SUPPLIED
L
OU
VER /
POWER VENT
ER
C
ONN
E
CTI
O
NS
TEST
SWITCH
T
RESET
PR
T
(
1) WH
ERE
P
OSSI
B
L
E
,
ALL SWI
T
CH
ES AND
C
I
RCUITRY ARE
S
HOWN IN THEIR AT REST
S
T
A
T
ES
.
N
OT
E
S
:
(2) ADDIT
I
O
N OF
EN
ERGY MANAGE
M
ENT
SYS
TEMS
O
R OPTIONAL LIMIT SWITCHES T
O TH
E T
ERMINAL
(
3
) S
CH
E
MATI
C IS WIRING DIAG
RAM, REF
E
R
T
O ACTUAL
C
OMPONENT
S F
OR EXACT
T
ERMI
N
AL
LOCA
TIONS
.
D
O
TTED
L
IN
E
IN
D
I
CAT
E
S
O
P
T
IO
NAL
E
Q
U
IP
M
E
N
T
IT
E
MIN
D
ICA
T
E
S
C
L
O
S
E
D
E
N
D
S
P
L
IC
E
JUNCT
IO
N
P
O
IN
T
(
E
L
E
C
T
R
I
C
A
LL
Y
S
A
ME)
T
=T
A
N
Y
=
Y
E
L
L
O
W
B
R
=
BRO
W
N
G
=
G
R
E
E
N
G
Y
=
G
R
A
Y
W
=
WH
IT
E
B
K
=
B
L
ACK
P
R
=
P
U
R
P
L
E
B
L
=
B
L
U
E
P
=
P
INK
O
=O
R
ANG
E
(4
)
WH
EN REPL
A
CING DAMA
GED WI
R
I
N
G, U
SE
EQ
UIVA
L
ENT TYPE AND
G
AUGE
.
TD
P
P
PROBE
BL/
BK
Y
P
UMP
S
TAGE #2
S
T
AGE
#
4
STAGE
#
3
A
E
PU
L
E
PR
H
I
G
H
LO
W
B
L
/
W
OPTI
O
NA
L
L
OUVER/VENTER
CO
NTROL
RE
L
AYS
R
R
= RE
L
AYS
L
OCATED ON CONTROL
P
ANEL
=
R
ELAYS
LOCATED IN
WIRING BOX
OPE
N
CLO
S
E
D
C
O
M
P
R
O
V
IN
G
R
EL
A
Y
C
2
NO
2
R/O
Y
/
G
=
YEL
L
O
W
WIT
H
G
R
EE
N
S
T
R
IP
E
R
=
R
E
D
R
E
L
A
Y
BOARD
HD#1
HD
#
2
ALARM
INPU
T 1
OPTIONAL
PR
A
1
B
1
A2 A3
B
2
B3
C
O
NTI
NUO
USL
Y
M
O
N
ITO
R
E
D
IN
T
E
R
M
IT
T
E
N
T
L
Y
M
ON
IT
O
R
E
D
F
IEL
D
INS
T
ALLE
D
SAF
E
T
Y DEVICES
NOT
E:
S
H
O
W
N
W
IT
H
S
H
O
R
T
I
N
G
BAR
S
R
E
M
O
V
E
D
A
ND A
T
T
A
CHE
D
D
E
V
I
C
E
S
I
N
N
O
N
-
A
L
ARM ST
A
T
E.
C
O
N
T
INUOU
SINT
E
R
M
ITT
E
NT
C
O
M
C
O
M
F
A
IL
O
KO
K
F
A
IL
HIGH/LO
W
G
A
S
,
AUX
.
H
I-LIM
I
T
A
UX.
L
IMITS
,
E
XT.
F
L
O
W
S
WIT
C
H
EXAMPLE DEVICES:
BK
1
0
9
8
1
3
4
5
6
7
2
2
9
47
5
6
4
2
3
4
2
3
S
T
AGE #
1
ST
A
GE #3
ST
A
GE #2
S
T
A
GE #4
P
R
B
R
1
2
6
5
4
3
O
UTLET
BR
BR
P
R
P
R
PR
2
4
V
AC
P
I
R
E
SET
P
S
F
F
T
H
2
4
C
O
M
MV
M/S
1
2
4
5
6
7
8
9
11
3
10
2
4
V
A
C
P
I
R
E
S
E
T
P
S
F
F
T
H
2
4
C
O
M
MV
M/S
1
2
4
5
6
7
8
9
11
3
10
-
+
LO
W
HIGH
-
+
S
T
ATUS
-
+
B
L
/W
8
9
7
6
4
5
4
1
3
6
5
T
6
P-SW#1
IGN#1-PS
IGN#2-PS
P-SW#2
-24
VAC
Y
Y
O
/
BK
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
~
3
4
1
P
R
O
V
IN
G
R
E
L
A
Y
BL
TERMINAL
STRIP
IGNITI
O
N
M
ODU
L
E
#
1
IG
NIT
ION
MO
DU
L
E
#
2
A
L
AR
M
I
NPUT
2
PR/
B
K
PR
P
BL/BK
GY
/W
GY/W
G
Y/
W
SYSTEM/
T
AN
K
O.A.
SENSOR
F
L
A
M
E
CUR
RENT
T
E
S
T
PIN
S
FLA
ME
CURR
ENT
T
E
ST PINS
R
T
1
R
T2
BK
W
W
BK
G
Y
G
Y
BR/W
2
BL/
BK
PUMP OPTIONA
L
O
N BOIL
E
RS
BL
WARNING:
THIS HEATER MAY BE
CONNECTED TO ONE OR MORE BRANCH
CIRCUITS. TO PR
EVENT ELECTRICAL SHOCK
,
ENSURE ALL
BRANCH CIRCUITS ARE DE
-
ENERGIZED BEFORE ATTEMPTING TO SERVICE
THIS EQUIPMENT.
OPTI
O
NA
L
B
O
IL
E
R
O
N
L
Y
I
NLET
R/BK
R
R
/
W
2
R
E
S
E
T
O
V
E
R
R
ID
E
3
HEAT
DEM
#
2
R
/
O
FIELD
I
N
ST
A
LL
A
S
NE
CESSARY
C
N.O
.
R
E
M
O
V
E
J
U
M
P
E
R
S
T
R
I
P
R
E
QU
I
RE
THE
R
EMOVAL
O
F
SOM
E
OF TH
E SHORT
ING
BARS
F
ROM
T
HE TE
RMINAL
ST
RIP.
NOTE:
SOME
S
T
A
GE
S
HAVE
MO
R
E T
HAN
O
N
E
GA
S
V
A
L
VES.
R
R
PR/BK
1
3
8
BL/BK
5
1
5
1
B
L
Y
Y
O
P
T
IO
N
A
L
P
R
FFR
P
P
R
AL
Y
P
Y
G
P
R
PR
= LE
DS LOCATED ON DISP
L
AY BOARD
~~~~
~~~~
=
OP
TIONA
L
DIN RAIL CONNECTORS
LOCATED
I
N EL
E
CT
RICA
L
WIRING BOX.
GND
C
C
N
O
N
O
PR
OPTIONA
L
H
I
G
H-LOW
G
AS
P
RESSURE SWIT
CHES
PR
LOW
HIGH
O/BK
IN
T
E
R
M
IT
T
EN
T
A
L
A
R
M
E
NA
B
L
E
R
E
L
A
Y
C
C
NO
NO
C
N
O
C
N
O
C
N
O
C
N
O
W
T
O
P
OWER
S
O
URCE
RESET
O
BL/BK
BL
Y
PR
PR
T