The mode is determined by the internal jumper settings (J2)

preventing common furnace pressure switch stuck open faults and system lockouts

Its lightweight yet durable 1

Key Benefits for Contractors Broad Operating Range: Temperature range of -40°F to +50°F makes it suitable for various medium and low-temperature R407C systems

Resideo L4006A1009 Aquastat Controller 321894-709 The mode is determined byThe Resideo L4006A1009 Aquastat Controller is a professional grade immersion temperature controller designed for precise regulation in hydronic heating systems, storage tanks, and boilers. This high or low limit aquastat utilizes a 3 8" x 2 7 8" copper sensing bulb to monitor liquid temperatures between 100F and 240F. Featuring internal SPST contacts that break on temperature rise, this unit is engineered for reliable safety shut off or cycling