2
AT
TO: 120 V
AC POWER
CIRCULA
TOR
120 V
A
C
INPUT
THERMOST
R
W
T
T
COM
24
VA
C
N/O N/C N/C N/O
NH
3
44
6
6
5
TO: ZC
SR501
1 ZONE
SWITCHING RELAY
POWER
T STAT
TO: ZR
ALTERNATIVE WIRING
(TANKLESS COIL)
T
S
R
50
1 Switc
hing R
elay W
ir
ing
AT
TO: 120 VAC
POWER
CIRCULA
TOR
JUMPER
120 V
A
C
INPUT
THERMOST
R
W
T
T
COM
24
VA
C
N/O N/C N/C N/O
NH
3
44
6
6
5
TO: TT ON BOILER
SR501
1 ZONE
SWITCHING RELAY
POWER
T STAT
TYPICAL WIRING
(COLD START)
T
TO: 120 V
AC POWER
CIRCULA
TOR
R
W
T
T
COM
24
VA
C
N/O N/C N/C N/O
NH
3
44
6
6
5
TO: TT ON BOILER
SR501
1 ZONE
SWITCHING RELAY
POWER *
T STAT *
ALTERNATIVE WIRING
(24 VAC POWERED INPUT SIGNAL)
N
H
REMOVE JUMPER.
DO NOT CONNECT POWER
TO N AND H TERMINALS.
*
T
STAT LIGHT WILL GO
ON AND OFF WITH 24 VAC
SIGNAL. POWER LIGHT
WILL ALWAYS BE OFF.
24 VAC
SIGNAL
Note:
When using Alternative W
iring diagram, the boiler oper-
ating control’
s ZC terminal will see the load of the cir
culator(s).
W
a
rning:
When using Alternative W
iring diagram, wiring
instructions must be followed so power originates from the boiler
aquastat. Failure to follow these wiring instructions may result in
a secondar
y sour
ce of power being connected to the boiler that
may activate it under certain cir
cumstances, causing injur
y or death.