Product description
The Grundfos MAGNA3 circulator pumps are designed for circulating liquids in the following systems:
• heating systems
• air-conditioning and cooling systems
• domestic hot-water systems.

The pump range can also be used in the following systems:
• ground source heat pump systems
• solar-heating systems.

Benefits
• Low energy consumption. The AUTOADAPT function ensures energy savings.
• FLOWADAPT which is a combination of the well-known AUTOADAPT control mode and a new FLOWLIMIT function.
• Built-in Grundfos differential-pressure and temperature sensor.
• Simple installation.
• No maintenance and long life.
• Extended user interface with TFT display.
• Control panel with self-explanatory push-buttons made of high-quality silicone.
• Operating log.
• Easy system optimisation.
• Heat energy monitor.
• External control and monitoring enabled via add-on modules.
• The complete range is available for a maximum system pressure of 16 bar (PN 16).

Main applications

Heating systems
• Main pump
• mixing loops
• domestic hot water
• heating surfaces
• air-conditioning surfaces.
The MAGNA3 circulator pumps are designed for circulating liquids in heating systems with variable flows where you want to optimise the setting of the pump duty point, thus reducing energy costs. The pumps are also suitable for domestic hot-water systems. Observe local legislation regarding pump house material. Grundfos strongly recommend that you use stainless-steel pumps in domestic hot-water applications to avoid corrosion.
To ensure correct operation, it is important that the sizing range of the system falls within the duty range of the pump.
The pump is especially suitable for installation in existing systems where the differential pressure across the pump is too high in periods with reduced flow demand. The pump is also suitable for new systems where automatic adjustment of the head to the actual flow demand is required, without using expensive bypass valves or similar components.
Furthermore, the pump is suitable for systems with hot-water priority as an external signal can immediately force the pump to operate according to the maximum curve, for example in solar-heating systems.

Characteristic features
• AUTOADAPT
• FLOWADAPT
• Proportional-pressure control
• Constant-pressure control
• Constant-temperature control
• Differential-temperature control
• Constant-curve duty
• Maximum or minimum curve duty
• FLOWLIMIT
• Automatic night setback
• No external motor protection required
• Insulating shells supplied with single-head pumps for heating systems
• Wide temperature range due to thermal separation of the control box and pump media
• Multipump function.

Pump selection
All pumps have a "best point" (ηmax), indicating where the pump is working most efficiently. Consider the parameters in the following section.

Pump size
The system characteristic is used together with the performance curve of the pump for sizing and correct pump selection.
The selection of pump size should be based on the following:
• required maximum flow
• maximum pressure loss in the system.

Additional operating modes for multipump setup

Multipump function
The multipump function enables the control of single-head pumps connected in parallel and twin-head pumps without the use of external controllers. The pumps in a multipump system communicate with each other via the wireless GENIair connection.
Pump system:
• Twin-head pump.
• Two single-head pumps connected in parallel. The pumps must be of equal size and type. Each pump requires a non-return valve in series with the pump. A multipump system is set up via a selected pump, i.e. the master pump (first selected pump). The multipump functions are described in the following sections.

Alternating operation
Only one pump is operating at a time. The change from one pump to the other depends on time or energy. If a pump fails, the other pump will take over automatically.

Backup operation
One pump is operating continuously. The backup pump is operated at intervals to prevent seizing up. If the duty pump stops due to a fault, the backup pump will start automatically.

Cascade operation
Cascade operation ensures that the pump performance is automatically adapted to the
consumption by switching pumps on or off. The system thus runs as energy-efficiently as possible with a constant pressure and a limited number of pumps.
The slave pump will start when the master pump is running at maximum or has a fault, and it will stop again when the master pump is running below 50 %. Cascade operation is available in constant speed and constant pressure. You can with advantage choose a twin head pump, as the backup pump will start for a short period in peak-load situations. If you have chosen an oversized single-head pump, it may run outside its best efficiency range most of the time.
All pumps in operation will run at equal speed. Pump changeover is automatic and depends on speed, operating hours and faults.