For Cold Start Boiler Application (Left)
Operation:When any thermostat calls for heat, the appropriate circulating pump is energized and the isolated end switch (X and X) will start the boiler.
For Tankless Coil Boiler Application (Right)
Operation:When any thermostat calls for heat, the boiler will be enabled andappropriate circulating pump is energized when the boiler temperature is above the set low limit and low limit (ZC) dip switch is set to on.
ZC and ZR Terminals: Connect terminal ZC to ZC terminal on the aquastatcontrol. Connect ZR to ZR terminal on the aquastat control. Confirm polarity is consistent between boiler aquastat and switching relay.
Priority Operation:When the priority dip switch is set to ON and the priority zone is actuated, all other zones will stop operation until priority zone is satisfied. When not switched to priority, all zones will operate independently.
Mode Operation: When the dip switch is set to NORMAL, the end switch relay will be energized if any zone is in operation. When the switch is set to RESET, the end switch relay will only be energized if the priority zone is in operation, or through the operation of a plug-in reset control.
Primary Pump Operation: When the dip switch is set to OFF, the primary circulating pump output will energize when any zone calls for heat, except the priority zone. When the dip switch is set to ON, the primary circulating pump output will energize when any zone calls for heat.
Post Purge Operation: When the dip switch is set to ON, the priority zone output will stay energized for 2 minutes after its thermostat or aquastat is satisfied, but not operate the boiler.
Priority Protection Operation: When the dip switch is set to ON, and if the priority zone calls continuously for more than one hour, power is returned to all the other zones, allowing each zone to function independently. Once the priority zone is satisfied, the control's autoreset is activated and the priority zone is again allowed to have priority for up to one hour starting from when it calls next.
Pump Exercise Operation: When the dip switch is set to ON, the solid state timer cycles all the circulating pumps that are attached to the Expandable Switching Relay at the selected time interval. The time interval can be set for the pumps to run for either 30 seconds every 2 weeks or for 4 minutes every 24 hours.
Low Limit (ZC) Operation: When the dip switch is set to ON and the boiler drops below the set low limit (terminal ZC connected to boiler), all zone circulating pumps will stop. When the boiler rises above the set low limit, the zone circulating pumps are allowed to operate.
End Switches (Dry Contacts): The main end switch closes when any zone thermostat calls for heat and the mode switch is set to NORMAL. The main end switch also closes when the mode switch is set to RESET and a PC Series boiler reset power control is calling for heat. The priority end switch closes only when the priority zone thermostat or aquastat is calling for heat.
Expansion Connections: Set the expansion switch to MASTER on the switching relay that has the designated priority zone or is utilizing the PC Series plug-in option. Set all other daisy chained controls to SLAVE. Using thermostat wire (18-22 gauge) connect between terminals A, B, C on the master control to the corresponding A, B, C on the SLAVE control(s). Controls may be daisy chained up to 20 zoning panels using any combination of -EXP controls (120 zones if all are 6 zone panels).
Technical Specification and Instruction Sheet : SR503-EXP-4, SR504-EXP-4, R506-EXP-4
Product CatalogProduct Catalog
Product Wiring Diagrams and Examples