MAGNA Series Cast Iron Pumps

Grundfos MAGNA Series cast iron circulator pumps are electronically controlled wet-rotor circulator pumps fitted with permanent magnet (PM) motors and compact stator technology, designed for circulating liquids in heating and cooling systems, ground source heat pump systems, chilled water systems, hydronic venting, snow melt, hot water recirculation, and solar heating applications. The MAGNA Series at SupplyHouse spans two product generations: the Grundfos MAGNA1, a high-efficiency circulator with permanent magnet motor and intuitive pump setting selection suited for basic performance needs where system communication is not required, and the Grundfos MAGNA3, the current-generation platform delivering maximum head up to 60 ft and flow up to 260 GPM in cast iron single-head models, with AUTOADAPT self-optimizing control that reduces energy consumption by up to 85% compared to a fixed-speed pump. Both generations use the canned-rotor design, meaning pump and motor form an integral unit with no shaft seal, no mechanical coupler, and bearings lubricated by the pumped liquid, resulting in maintenance-free operation and low life cycle cost. All MAGNA Series cast iron pumps use flanged connections and are single-phase units available in 115V, 115-230V, 208-230V, and 208V configurations depending on the model.

KEY SUBCATEGORIES / PRODUCT TYPES

Grundfos MAGNA1 Cast Iron Circulator Pumps

Grundfos MAGNA1 cast iron circulator pumps are the entry-level generation of the MAGNA Series, designed for heating systems with variable flows where proportional-pressure, constant-pressure, or constant-curve speed control is needed without the advanced communications capability of the MAGNA3. The MAGNA1 is a canned-rotor type with no shaft seal, bearings lubricated by the pumped liquid, and no maintenance requirements. Control options include three proportional-pressure curves, three constant-pressure curves, and three fixed-speed curves, selectable via nine light field indicators on the pump. All MAGNA1 pumps comply with EuP 2013 and 2015 energy efficiency requirements. Models carried include the MAGNA1 32-60 GF (SKU 98126819, 1/6 HP, 115-230V), MAGNA1 32-100 GF 15/26 (SKU 98126823, 115/230V), MAGNA1 40-80 F GF 15/65-40/43 (SKU 98126799, 1/3 HP, 115V), MAGNA1 40-120 GF (SKU 98126831, 1/2 HP, 216-230V), and MAGNA1 65-120 F GF 65 (SKU 98126847, 1 HP, 208/230V). The MAGNA1 is the ideal choice for replacement of older circulators and for applications where system communication is not required.

Grundfos MAGNA3 Single-Head Cast Iron Circulator Pumps - Small to Medium

Grundfos MAGNA3 single-head cast iron circulators in the smaller capacity range include the MAGNA3 32-60 F (SKU 98126820, 1/6 HP, 115-230V), MAGNA3 32-100 F (SKU 98126824, 1/6 HP, 115-230V), and MAGNA3 32-120 15-26 F (SKU 99833304, 1/6 HP, 115-230V). These models are suited for residential and lighter commercial heating, cooling, and hot water recirculation where the upgraded MAGNA3-32 platform expands the efficiency advantages into lower-demand applications. The MAGNA3 40-80 F (SKU 98126800, 1/3 HP, 115V, max 81 GPM, max 175 PSI) and MAGNA3 40-120 F models in both 115V (SKU 98126804, 3/4 HP) and 208-230V (SKU 98126832, 1/2 HP) cover mid-range commercial applications. All MAGNA3 single-head models are fitted with GENIair wireless communication as standard and the innovative clamp with a single screw that enables easy repositioning of the pump head for installation access. The Grundfos Eye LED provides visual indication of pump status, running, warning, or alarm, at a glance.

Grundfos MAGNA3 Single-Head Cast Iron Circulator Pumps - Large

Grundfos MAGNA3 large single-head cast iron models serve high-flow commercial and mechanical applications. The MAGNA3 50-80 GF 240 (SKU 98126812, 1/3 HP, 115V, max 174 PSI, liquid temperature range 14°F to 230°F) and MAGNA3 50-150 F GF 53 (SKU 98126816, 3/4 HP, 115V) serve medium-to-large commercial installations at 115V. The MAGNA3 50-150 F (SKU 98126844, 208-230V, max 38 GPM, max 174 PSI) and MAGNA3 65-120 F (SKU 98126848, 1 HP, 208-230V) and MAGNA3 65-150 F (SKU 98126852, 1-1/2 HP, 208-230V) cover the largest single-head cast iron configurations. The MAGNA3 80-100 F (SKU 98126856, 208-230V, max 260 GPM, max 174 PSI) is the highest-flow single-head cast iron model in the lineup. The MAGNA3 incorporates a 4-pole synchronous permanent magnet motor, an integrated frequency converter, and an integrated differential-pressure and temperature sensor in the pump body.

Grundfos MAGNA3 Twin-Head Cast Iron Circulator Pumps

Grundfos MAGNA3 D (twin) cast iron circulators are dual-head pump assemblies sharing a common flange, designed for redundancy and high-reliability applications where continuous circulation is required and a standby pump is needed on the same connection. Twin models in the cast iron lineup include the MAGNA3 D 65-150 F (SKU 98126863, 208-230V) and MAGNA3 D 80-100 GF (SKU 98126864, 1-1/2 HP, 230V). The wireless multi-pump control feature includes a built-in wizard that makes connecting a parallel-coupled pump quick and easy from the pump's on-board interface. Twin-head models are available for the three largest operational capacities in the MAGNA3 cast iron range.

BUYING GUIDE / HOW TO CHOOSE

Selecting the right Grundfos MAGNA Series cast iron circulator starts with the system type and performance requirement. MAGNA1 is the correct specification when a reliable, energy-efficient variable-speed circulator is needed without advanced communications, system monitoring, or AUTOADAPT self-optimization. The MAGNA1 covers heating, cooling, and domestic hot water recirculation applications with proportional-pressure, constant-pressure, and fixed-speed control in a straightforward interface. MAGNA3 is the specification when the application demands intelligent self-optimizing control, built-in diagnostics, GENIair wireless communication, or the advanced control modes including FLOWLimit and FLOWAdapt that can replace pump throttling valves entirely.

For MAGNA3 applications, the AUTOADAPT control mode is the factory default and the right starting point for most installations. After installation, AUTOADAPT analyzes the heating system demands, finds the optimal setting, and continuously adjusts to changes in system demand. No manual commissioning of the setpoint is required. For applications where a maximum flow limit is required, such as main pump applications in boiler systems where a steady flow through the boiler is needed, FLOWAdapt combines AUTOADAPT with FLOWLimit, eliminating the need for pump throttling valves at each zone and reducing installed cost.

Size selection requires matching the model designation to the system's flow and head requirements. The MAGNA Series model numbering encodes the nominal connection size and maximum head: a MAGNA3 32-100 has a DN32 connection and a maximum head of approximately 100 feet of water. Confirming the actual system flow and head requirements against Grundfos's selection tools or pump curves before specifying is required, as operating outside the duty range can result in suboptimal performance or incorrect pump operation.

Voltage selection is straightforward but requires confirmation before ordering. MAGNA3 models in the 32 series operate at 115-230V (single phase, autoswitching). Larger models in the 40 through 80 series are available in 115V or 208-230V variants depending on the specific model. Confirming the available service voltage at the installation point before ordering prevents a mismatch. For redundancy applications on large mechanical systems, the MAGNA3 D twin-head models provide a standby pump on the same flange connection without additional piping.

FAQs

What is the Grundfos MAGNA Series and what are MAGNA Series cast iron pumps used for?

Grundfos MAGNA Series cast iron pumps are electronically controlled wet-rotor circulator pumps with permanent magnet motors designed for variable-flow liquid circulation in heating and cooling systems, ground source heat pump systems, chilled water systems, domestic hot water recirculation, hydronic venting, snow melt, and solar heating applications. MAGNA Series cast iron pumps use the canned-rotor design: pump and motor form an integral unit with no shaft seal and no mechanical coupler, with bearings lubricated by the pumped liquid for maintenance-free operation. The series spans two generations, MAGNA1 for basic performance applications and MAGNA3 for intelligent self-optimizing control.

What is the difference between the Grundfos MAGNA1 and MAGNA3?

The difference between the Grundfos MAGNA1 and MAGNA3 is the control intelligence and communications capability. The MAGNA1 uses a permanent magnet motor with manually selectable proportional-pressure, constant-pressure, and fixed-speed curves via nine light field indicators, complies with EuP energy efficiency requirements, and is the correct choice for applications where system communication is not required. The MAGNA3 adds AUTOADAPT self-optimizing control that reduces energy consumption by up to 85%, FLOWLimit and FLOWAdapt control modes that can replace pump throttling valves, GENIair wireless communication as standard, an integrated differential-pressure and temperature sensor, built-in diagnostics with energy tracking and logging, a Grundfos Eye LED status indicator, and Grundfos GO smartphone interface access regardless of pump location.

What is AUTOADAPT on the Grundfos MAGNA3 and how does it work?

AUTOADAPT on the Grundfos MAGNA3 is an automatic self-optimizing control mode, factory-set as the default, that analyzes the heating system's demands after installation and continuously adjusts the pump's operation to match actual flow requirements. AUTOADAPT reduces energy consumption by up to 85% compared to a fixed-speed pump by operating the pump at the minimum power needed to satisfy the system demand at any given moment, rather than running at a fixed setpoint. For most residential and commercial heating applications, an installer can leave the MAGNA3 on the factory AUTOADAPT setting, and the pump will self-commission and self-optimize without manual setpoint adjustment.

What is FLOWLimit on the Grundfos MAGNA3 and when should it be specified?

FLOWLimit on the Grundfos MAGNA3 is a control function that restricts the maximum flow the pump delivers, eliminating the need for pump throttling valves in the system. FLOWLimit can be specified for main pump applications in boiler systems where a steady flow through the boiler is required, for mixing loop systems where a precise maximum flow for each zone can be set to ensure sufficient heat energy delivery, and for any system where balancing valves would otherwise be required. FLOWAdapt combines AUTOADAPT with FLOWLimit, so the pump continuously self-optimizes while also respecting the set maximum flow limit.

What is the maximum flow and pressure for MAGNA3 cast iron models, and are twin-head models available?

Grundfos MAGNA3 cast iron single-head models cover up to 260 GPM (the MAGNA3 80-100 F, SKU 98126856, 208-230V) at a maximum working pressure of 174 PSI. The liquid temperature range for cast iron MAGNA3 models is 14°F to 230°F. Twin-head (MAGNA3 D) cast iron models are available for the three largest operational capacities, including the MAGNA3 D 65-150 F (SKU 98126863, 208-230V) and MAGNA3 D 80-100 GF (SKU 98126864, 1-1/2 HP, 230V), providing built-in redundancy with a standby pump on the same flange connection. The MAGNA3 overall platform covers maximum head up to 60 ft and flow up to 550 GPM across the full cast iron and stainless steel range.