HONEYWELL AQ2574V4 Aquatrol Zoning Panel for 4 Zones of Valves with End Switches. Zone expansion panel works with AQ1000 communicating thermostat to add up to 4 zones with zone valves with end switches to AQ2000 Series Boiler Control Panels.
• R-C transformer and B-B data bus terminal for easy expansion
• Status LCDs for easy diagnostics
• Use with 2-wire “polarity insensitive” communicating thermostats
• Replacement Parts: AQ1574V4 4-zone pump expansion module, AQ10X38 24 Vac 38 VA transformer.