Xylem Aquastat Controls

Overview

The XYLEM 343200 is a replacement bellows assembly designed for use in low water cutoff controls on steam boiler systems. The bellows element responds to pressure changes inside the control body, actuating the electrical switch contacts that monitor and maintain safe boiler water levels. When water drops below the safe threshold, the bellows triggers the cutoff switch, stopping burner operation and preventing dry firing. Licensed HVAC technicians and boiler service professionals install this assembly as a direct replacement when the original bellows shows signs of fatigue, leakage, or failure to actuate reliably. At 1.37 pounds, it is a compact, service-ready component. This bellows assembly is suited for residential and commercial steam heating systems that use McDonnell Miller low water cutoff controls. It is a factory-specified replacement for the SA63-5 bellows assembly within the control housing. Proper function of this component is critical to boiler safety, as it directly governs the dry-fire protection response. It is intended for service calls and planned maintenance where the control body remains in place and only the internal bellows assembly requires replacement. Key Features Direct replacement for the SA63-5 bellows assembly in McDonnell Miller low water cutoff controls Actuates electrical switch contacts in response to pressure changes inside the control Prevents dry firing by triggering burner shutoff when water level drops below safe threshold Suitable for…