The AQ250 family of AQUATROL Boiler Controls provides simplified, energy-efficient control of single temperature, residential hydronic heating systems. The AQ250 easily converts a single zone heating system into a room-by-room comfort control system, or upgrades a basic, relay-logic zoning system to intelligent Zone of Greatest Demand control for increased energy efficiency with reduced boiler cycling. AQ250 boiler controls can ensure ample supply of hot water for both space heating and priority generation of domestic hot water for bathing, dishes and laundry.

  • Controls up to 2 stages of heat from a single thermostat.
  • Use with AQ1000 2-wire communicating thermostats, or most dry contact digital thermostats.
  • Zoning Control for up to 4 zones as shipped; can be expanded to a total of 16 zones with AQ255 or AQ257 expansion zoning panels and up to 64 zones when used with AQ254 Add-A-Temp panels.
  • Line or low-voltage output for zoning equipment (pumps or valves).
  • Zone synchronization through Zone or Greatest Demand control.
  • Domestic hot water priority and priority override protection.
  • Boiler short cycling protection.
  • Boiler post purge.
  • Freeze protection.
  • Pump/valve exercise.
  • Boiler shock prevention from cold water returning to boiler.
  • Automated test feature for quick start-up and simplified troubleshooting.
  • Integral 38 VA transformer with self-resetting electronic fuse.
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Boiler Control for Zoned Hydronic Systems
Thermostat Compatibility:
AQ1000 Series 2-wire
Most Digital Thermostats
User Interface:
DIP Switch
Boiler Heat Post Purge:
30 Seconds
Pump Valve/Excercise:
30 seconds per 2 weeks of space heating inactivity
10 Ft
Heat Demand Input:
External dry contacts connection only
DHW Demand Input:
External dry contacts connection only
Boiler Output Rating:
24 Vac 0.5A 12VA
ZR-ZC Contact Rating:
120 to 240 Vac 1/3 HP
Boiler Pump Output:
120 Vac/250 Vac 5A 1/3HP
DHW Pump/Valve Output:
120 Vac/250 Vac 5A 1/3HP
Auxiliary Pump Output:
Dry contact output 120 Vac/250 Vac 5A 1/3 HP
Zone Output Contact:
Pumps: 120 Vac/250 Vac 5A 1/3 HP
Valves: 24 Vac 0.5 A 12 VA
Control Temp Range (F):
32 F to 130 F
Operating Humidity:
5 to 90% RH non-condensing
13" wide x 8" high x 3-3/8" deep
Zoning Devices Controlled:
Zone Valves w/ End Switches
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