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Grundfos 92603108 Pump

Grundfos 92603108 Pump

Grundfos

The Grundfos 92603108 ALPHA 15-58 FR Circulator Pump is a 115V, 60 Hz, single-phase wet-rotor circulator driven by an electronically commutated motor (ECM) and built for closed-loop hydronic heating. It moves water through boilers, baseboard and radiator zones and radiant heating loops, and it adjusts motor speed to the load instead of running flat out the way an old fixed-speed circulator does. In the model code, ALPHA is the product family, 15 is the small-circulator size, 58 is the maximum head in decimeters (5.8 m), and FR is the rotated flange connection. Grundfos literature lists part 92603108 as the ALPHA 15-58 FRC, a cast-iron rotated flange pump with an integral check valve.

The published ratings are a maximum flow of 13.6 GPM (3.1 m³/h), a maximum head of 19 ft, and a rated duty point of 8.37 GPM at 11.16 ft. Power input runs from 3.4 W to 38 W with a maximum current draw of 0.71 A, and the pump carries a HI Energy Rating of 193 and TF class 110. It handles liquid from 36°F to 230°F at up to 175 psi working pressure. Construction is a cast-iron pump housing with a composite impeller, a GF 15/26 flange connection and a flange-to-flange length of about 6-1/2 in. Control options include constant pressure, proportional pressure and constant curve modes, each with three fixed settings, plus an AUTOADAPT setting that reads the system and removes the guesswork, and a constant flow mode. The pump pairs over Bluetooth with the Grundfos GO app for guided setup, the event log, air detection and venting, firmware updates and trend data for flow, head and media temperature. Power lands on a toolless removable connector at a compact terminal box with conduit connections, so the wiring can be done outside the box.

For replacement work, the Grundfos cross-reference lists the ALPHA 15-58 against the Taco 0015/0015e3 and the B&G ecocirc 19-14, and the series succeeds the earlier ALPHA1 15-55. Its sibling, 92603115 (ALPHA 15-58 FC), is the same pump on a standard cast-iron flange with check valve, so confirm which flange orientation your piping needs before ordering. Install the pump with the motor shaft horizontal, the flow arrow on the housing pointing with the system flow, and fresh gaskets at both isolation flanges. Purge the loop, then run the air detection and venting routine from the GO app, because trapped air is the most common reason a new circulator sounds noisy or moves little water. If a zone runs hot or cold, check that the control mode matches the system: constant pressure suits zone-valve systems, proportional pressure suits systems with thermostatic radiator valves, and constant curve suits zone-pump systems. Before condemning the pump, read the event log, confirm power at the terminal box, and make sure the isolation valves are fully open.

Key Benefits

  • Low Power Draw: the ECM motor holds input to 3.4 W–38 W and earns a HI Energy Rating of 193, which cuts the electric cost of running a hydronic heating loop all season.
  • Drop-In Fit: the GF 15/26 rotated flange and integral check valve let the pump stand in for common circulators such as the Taco 0015/0015e3 and B&G ecocirc 19-14 without adding a separate check.
  • Smart Control: AUTOADAPT, constant pressure, proportional pressure, constant curve and constant flow modes match the pump to zone-valve, zone-pump and radiant layouts, with setup and diagnostics through Grundfos GO.
  • Protection and Quiet Running: a robust startup, self-venting function and dry-run protection help the pump clear air and keep running, at a sound level of roughly 25 dB(A).

Common Questions

  • What is the difference between the 92603108 and the 92603115? The 92603108 (ALPHA 15-58 FR, listed by Grundfos as ALPHA 15-58 FRC) has the rotated flange, while the 92603115 (ALPHA 15-58 FC) has the standard flange. Both are 115V cast-iron pumps with an integral check valve.
  • Why do some listings show 8.37 GPM and 11.16 ft while others show 13.6 GPM and 19 ft? 8.37 GPM at 11.16 ft is the rated duty point; 13.6 GPM and 19 ft are the maximum flow and maximum head of the ALPHA 15-58. Actual performance follows the system curve and the control mode selected.
  • Can the 92603108 replace my existing circulator? Usually, if the required flow and head fall inside 13.6 GPM and 19 ft, the flange orientation and connection suit the piping, and the system is a closed heating loop. The cast-iron housing is not intended for open potable water systems.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.