Taco SR503-EXP

2
AT
TO: 120 VAC POWER
CIRCULATOR
120 VAC
INPUT
THERMOST
R
W
T
T
COM
24
VAC
N/O N/C N/C N/O
NH3
4466
5
TO: ZC
SR501
1 ZONE
SWITCHING RELAY
POWER T STAT
TO: ZR
ALTERNATIVE WIRING
(TANKLESS COIL)
T
SR501 Switching Relay Wiring
AT
TO: 120 VAC
POWER
CIRCULATOR
JUMPER
120 VAC
INPUT
THERMOST
R
W
T
T
COM
24
VAC
N/O N/C N/C N/O
NH3
4466
5
TO: TT ON BOILER
SR501
1 ZONE
SWITCHING RELAY
POWER T STAT
TYPICAL WIRING
(COLD START)
T
TO: 120 VAC POWER
CIRCULATOR
R
W
T
T
COM
24
VAC
N/O N/C N/C N/O
NH3
4466
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 Wiring diagram, the boiler oper- ating control’s ZC terminal will see the load of the circulator(s). Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances, causing injury or death.