Product Brochure

Switching Relays
Product Number Transformer Maximum Dimensions of Enclosure
Number of Zones Voltage Combined Load Width Height Depth
SR501 1 Zone 120 VAC Input 12 amps 4-7/8” 6-5/8” 2-3/8”
SR501-HC 1 or 2 Zone 120 VAC Input 20 amps 4-7/8” 6-5/8” 2-3/8”
SR502 2 with Priority 120 VAC Input 15 amps 10-1/4” 7” 2-3/4”
SR503 3 with Priority 120 VAC Input 15 amps 10-1/4” 7” 2-3/4”
SR504 4 with Priority 120 VAC Input 20 amps 10-1/4” 7” 2-3/4”
SR506 6 with Priority 120 VAC Input 20 amps 12-1/4” 8” 3”
Expandable Switching Relays
Product Number PowerPort Power Control Transformer Maximum Dimensions of Enclosure
Number of Zones Slots Plugs Voltage Combined Load Width Height Depth
SR501-EXP 1 Zone 0 1 120 VAC Input 12 amps 4-1/4” 6-5/8” 2-3/8”
SR503-EXP 3 with Priority 3 1 120 VAC Input 15 amps 10-1/4” 7” 2-3/4”
SR504-EXP 4 with Priority 3 1 120 VAC Input 20 amps 10-1/4” 7” 2-3/4”
SR506-EXP 6 with Priority 3 1 120 VAC Input 20 amps 12-1/4” 8” 3”
All circulator relay connections, including ZC/ZR, are rated 1/3 hp, 6 amps at 120 VAC. End switch connections are rated 24 VAC, 1 amp.
All thermostat connections supply a 24 VAC class 2 output. SR501-HC has a single phase motor rating per zone of 3/4 hp (13.8 A) @ 120 VAC
Switching Relays
Taco Switching Relays combine clearly labeled PC board layouts with advanced
features that allow for total system customization. Whether using basic priority
switching or the advanced features of the -EXP controls, the job is made easy.
External indicator lights provide instant diagnostic feedback, making a snap of
service calls or new installation start-ups. All switching relays are UL listed, are
compatible with conventional and programmable thermostats.
Taco Expandable Switching Relays
Whether you want to expand up to 120 zones or utilize the advanced features
of the Add-on Power Controls, Taco -EXP controls allow for simple integration of
advanced features. Built-in Post Purge and Pump Exercise functions can optimize
the operation of any system.
Features
Front Diagnostic Lights
Switchable Priority
Built-in Priority Protection
Simplified Wiring
Premium Sealed Relays
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Contractor Friendly PC Board Layout
Universal Thermostat Compatibility
24 Volt Power Output
for hard wired thermostats
Field Replaceable Transformer
UL Approved
Extended 3 Year Warranty
Additional -EXP Features
Add-on Power Control Plug
Built-in; Post Purge and
Pump Exercise Functions
Switchable Primary
Circulator Output
Two boiler contacts, utilizes
full functionality of Mod-Con boilers
Expandable to 20 Zoning Panels
(120 zones if all are 6 zone panels)
Interface with -EXP Zone Valve
Controls
The Taco Connection
Combine the reliability of the
Taco Zone Valves, Priority Zoning
Circulators, Thermostats, and the
00® family of circulators with the
advanced features of the Taco Zone
Controls to achieve total system
integration. No matter the applica-
tion, Taco now provides the products
to maximize system performance
while simplifying both installation
and service.
External Diagnostics
It’s no longer necessary to open
the box to troubleshoot the system.
Externally visible lights show full
functionality of the switching relay.
The green light should always be on,
indicating that power is connected.
When the thermostat calls for heat,
both the appropriate circulator and
red indicating light is energized.
Submittal Data Information
Switching Relay
120 VAC INPUT
FOUR ZONE SWITCHING RELAY
120 VAC CIRCULATORS
ZC
INPUT
120 VAC
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE1 ZONE2 ZONE3
THERMOSTATS
SR 504-4
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
X X R W R W R W R W
ISOLATED
END
SWITCH
THERMOSTATS (24 VAC)
PRIORITY
120 VAC
ZR
H H N H N H N H N H N H
ZONE4
ZONE 2
POWER
ZONE 1
ZONE 3
ZONE 4
LED
INDICATORS
ZONE 4
PRIORITY
OFF
ON
PRIORITY
TO: "TT" ON
BOILER
JUMPER
24 VAC
COM
120 VAC INPUT
FOUR ZONE SWITCHING RELAY
120 VAC CIRCULATORS
ZC
INPUT
120 VAC
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE1 ZONE2 ZONE3
THERMOSTATS
SR 504-4
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
FUSE
6 AMP
X X R W R W R W R W
ISOLATED
END
SWITCH
THERMOSTATS (24 VAC)
PRIORITY
120 VAC
ZR
H H N H N H N H N H N H
ZONE4
ZONE 2
POWER
ZONE 1
ZONE 3
ZONE 4
LED
INDICATORS
ZONE 4
PRIORITY
OFF
ON
PRIORITY
TO: "ZC"
ON BOILER
TO: "ZR"
ON BOILER
24 VAC
COM
Cold Start Boiler
Application
Tankless Coil Boiler
Application
(Alternative Wiring)
Submittal Data # 101-191 & 102-381 Eective: 12/08/20
Supersedes: 08/09/17
Wiring Diagram
Add-on Power Controls*
PC700 Boiler Reset Control
PC702 Two Stage Boiler Reset Control
PC705 Variable Speed Pump Injection Mixing Control
*For use with -EXP controls.
Taco Inc., 1160 Cranston Street, Cranston, RI 02920 / [phone] / Fax [phone]
Taco (Canada) Ltd., 8450 Lawson Road, Unit #3, Milton, Ontario L9T 0J8 / [phone] / Fax [phone]
www.TacoComfort.com