The Caleffi ZSR103 is a Z-one 3-zone circulator control relay.
Best for coordinating multiple zones, circulators and the heat source from one enclosure.
Specifications sourced from Caleffi North America technical literature. Last reviewed July 2026.
Key Features
Circulator Switching
Switches 3 zone circulators from thermostat calls, so each zone pump runs only when its zone is calling.
Boiler Interlock
Provides the end-switch contact so the heat source fires only when at least one circulator is running.
Technical Specifications
| Product Type | Zone Control Relay |
| Electric supply | 120 V (AC) |
| Series | Z-one Pump Control |
Documentation
Design Resources
Related Products
- Caleffi ZSR101 : Z-one 1-Zone Pump Relay
- Caleffi ZSR104 : Z-one 4-Zone Pump Relay
- Caleffi ZSR106 : Z-one 6-Zone Pump Relay
Frequently Asked Questions
What does Caleffi ZSR103 control?
It is a zone pump control relay. It switches 3 zone circulator(s) from thermostat calls and provides the boiler interlock so the heat source fires only when a circulator is running.
Can Caleffi ZSR103 drive zone valves instead?
No. This board switches circulators. Caleffi's ZVR series is the equivalent board for zone valve actuators, which have a different load and end-switch arrangement.
What supply voltage does Caleffi ZSR103 require?
Electric supply is 120 V (AC).
What is the warranty on Caleffi ZSR103?
Caleffi covers this product under its standard two-year limited warranty against defects in material and workmanship from the date of shipment. ZOT Supply is an authorized Caleffi distributor.
- Product Type:
- Zone Control Relay
- Product Family:
- Z-one Zone Controls
- Series:
- Z-one Pump Control
- Zones:
- 3
- Electric Supply:
- 120 V (AC)