Home / HVAC / Boiler Aquastat Control 550002858 Boiler Aquastat Control 550002858$464.14 Price may not be up-to-date. In Stock View Product Part Number: 550002858 Brand: DUNKIRK RADIATOR CORPORATION Seller: Sears PartsDirect Category: HVAC 60-day return policy Description This aquastat control (part number 550002858) is for boilers. Aquastat control 550002858 monitors and controls water temperature inside the boiler tank. Wear work gloves to protect your hands when installing this part.