• Built-in thermal overload protection Armstrong Series S in-line circulators are built using a standard three-piece design that features a radially-split body, oversized shaft, centrifugal impeller, sintered silicon carbide seal and modular construction The radially-split body can be left in line while servicing the pump, eliminating cumbersome disconnecting of pipes Armstrong circulating pumps have an oversized shaft made from either special alloy steel (sleeve bearing design) or stainless steel (maintenance-free design) machined to exacting tolerance The balanced, centrifugal design impeller ensures maximum water delivery in the HVACs system Positive mechanical seal Modular construction

Armstrong series S and H in-line circulators are suitable for applications such as hydronics heating and cooling, domestic water systems, multi-stage zoning and general industrial service. Both models are available in a wide range of sizes to match the performance requirements of any of these applications. Armstrong series S and H circulators are durable and trusted products that have been used by HVACs professionals for decades. Besides the existing sleeve bearing design, Armstrong now has introduced the 'maintenance free' design which has permanently lubricated ball bearings and require no maintenance at all.