H
3
5
4
N/O
N/C
6
N
SR501
1 ZONE
SWITCHING RELAY
120 VAC
INPUT
T
COM
W
R
24
VAC
P
ZC
X1
ZR
X2
FUSE 1 AMP
24 VAC
POWER
TWO ZONE SWITCHING RELAY
SR 502
ZONE1
ZONE2
ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
SR 503
SR503-EXP
ON
OFF
ZONE 3
PRIORITY
RESET
NORMAL
POWER CONTROL INTERFACE
MASTER
SLAVE
1
2
EXPANSION
PLUG-IN CARDS
120 VOLT CIRCULATORS
END
SWITCH
X
FOUR ZONE SWITCHING RELAY
SR504
ZONE 4
ZONE4
SR504-EXP
SIX ZONE SWITCHING RELAY
SR506
ZONE6
ZONE5
ZONE 6
SR506-EXP
SR501-845RP
UNIVERSAL REPLACEMENT RELAY
L1
L2
Thermostat
Boiler
IN
OUT
Priority
Power In
Priority Zone Circulator
XXX-Z
POWER INPUT
120VAC INPUT
120VAC OUTPUT
CIRC OUTPUT
PRIORITY OUTPUT
FUSE
5 AMP
1 AMP
THERMOSTAT
T/R
T/W
RESET OVERRIDE
END SWITCH
MODE
POWER CONTROLS
SR501-EXP