OEM Lennox Aquastat High/Low Limit Controller — 48X63

The genuine OEM Lennox 48X63 is a circulator control aquastat that provides both high limit and low limit temperature control in hydronic and boiler applications. It senses water temperature and manages the circulator pump and burner operation, keeping boiler water within a safe and efficient range while ensuring the circulator only runs when water is hot enough to deliver useful heat.

When an aquastat controller fails, you may experience no heat, a circulator that runs continuously or not at all, boiler short-cycling, water temperatures that overshoot or never reach setpoint, or nuisance safety lockouts. A drifting or stuck limit can also cause the burner to fire without proper temperature regulation.

The OEM 48X63 is calibrated to the exact high and low limit setpoints your Lennox equipment requires. Substitute aquastats often have different switching temperatures, terminal layouts, or sensor characteristics that compromise safety and comfort. This factory controller guarantees correct calibration, reliable limit protection, and proper circulator sequencing for your Lennox system.