The Taco Wood Boiler Series Hi-Capacity circulators are designed specifically for use on unpressurized outdoor wood boiler applications. Features include a quiet running, close-coupled, thermally protected motor assembly with permanent split-capacitor and permanently lubricated bearings. A stainless steel shaft, silicon-carbide mechanical seal and non-ferrous impeller make the Wood Boiler Series Circulator an ideal choice for years of maintenance-free operation. Note: Use Stainless Steel body circulators on open systems for the best corrosion protection.