CALEFFI - Z-One 1, 3, 4 zone pump Control

The Caleffi Z-one™ ZSR Series pump control provides centralized circulator and boiler control for zoned hydronic heating and cooling systems. Available in 1-, 3-, and 4-zone configurations, the relay accepts calls from low-voltage thermostats and activates the corresponding 120V circulator pump while enabling the boiler through dry contacts. Multi-zone models provide a dedicated primary-pump output, selectable domestic hot water priority, pump exercising, post-purge operation, remote enable, LED diagnostics, and Z-oneLink™ expansion. Designed for efficient installation and simplified troubleshooting, these Caleffi hydronic relay controls are ideal for boilers, radiant floor heating, baseboard systems, fan coils, and indirect water heaters.

Cross References

Caleffi — ZSR101: Single-zone pump control with two independent relay outputs

Caleffi — ZSR103: Three-zone circulator pump control with primary-pump output and priority capability

Caleffi — ZSR104: Four-zone circulator pump control with primary-pump output and priority capability

Usage

The Caleffi ZSR control is mounted near the boiler and connected to the building’s thermostats, circulator pumps, and boiler operating terminals. When a thermostat calls for heat, the relay energizes the corresponding 120V zone circulator and closes the boiler dry contact so the heat source can operate. On the ZSR103 and ZSR104, Zone 1 can be configured as a priority zone for an indirect domestic hot water tank. During a priority call, the controller can temporarily stop the space-heating circulators, operate the priority pump, and then provide a selectable post-purge cycle after the demand ends.