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TACOZone-Switching Relays

TACO SR503-5 Zone-Switching Relay, 3 Zones with Priority, 120V AC

The TACO SR503-5 is a zone-switching relay with 3 zones with priority, operating on a 120V AC primary supply. It supports a full-load amperage (FLA) of 20 A at 120V AC. This switching relay is designed for zone…

SKU 3G-OTH-67263

Also listed as: SR5035 · SR503 5

Brand
TACO
Item
SR503-5 Zone-Switching Relay, 3 Zones with Priority, 120V AC
Part Number
SR503-5
Category
Zone-Switching Relays
Available to Order
Also known as:SR503-5TACO
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Technical Specifications

TACO
Manufacturer Part Number
SR503-5
Type
3 with Priority Zones
AC Primary
120V
Number of Zones
3 with Priority
Power Port Slots
0
Current Ratings @ Voltages
FLA: 20 A @ 120V AC

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TACO Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The TACO SR503-5 is a zone-switching relay with 3 zones with priority, operating on a 120V AC primary supply. It supports a full-load amperage (FLA) of 20 A at 120V AC. This switching relay is designed for zone control in hydronic heating systems.

Frequently Asked Questions

What is the TACO SR503-5 zone switching relay used for?

The TACO SR503-5 is used for zone control in hydronic heating systems. It switches circulator pumps or valves based on thermostat calls, with 3 zones including a priority zone to ensure the primary zone gets heat first.

What are the specifications of the TACO SR503-5?

The TACO SR503-5 is a 3-zone switching relay with priority, operating on 120V AC primary supply. It has a full-load amperage (FLA) of 20 A at 120V AC. The manufacturer part number is SR503-5.

Where to buy the TACO SR503-5 worldwide?

You can source the TACO SR503-5 through 3G Electric, a global industrial equipment distributor. We handle full logistics, customs clearance, and delivery to worldwide destinations. Contact us for availability and lead time.

How to install the TACO SR503-5 zone switching relay?

Install the TACO SR503-5 by mounting it on a wall or panel, connecting the 120V AC primary supply, and wiring each zone's thermostat and circulator. Follow the wiring diagram provided by TACO. Ensure power is off before installation and consult a licensed electrician.

Used in

Common applications for TACO
Hydronic heating systems — Taco 49-150T-2 inline air separator removes entrained air to maintain loop efficiency.
Domestic hot water recirculation — Taco HLS-1 under-sink pump reduces wait time at fixtures in residential buildings.
Chilled water cooling loops — Taco SFL-150S isolation flange allows equipment service without system drain.
Circulator pump maintenance — Taco 110-009RP motor coupler restores torque transfer in Series 110 pumps.
Water/glycol systems — Taco 49-200T-2 air separator handles 2 in NPT connections at 150 psi and 240°F.
Commercial hydronic balancing — Taco air separators and isolation flanges support efficient fluid control and serviceability.
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TACO Products

3G Electric supplies TACO zone-switching relays. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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