EVAK Residox 750 Automatic Puddle Pump

EVAK Residox 750 Automatic Puddle Pump | High Flow Sensor Pump | 230V

The EVAK Residox 750 Automatic pairs the higher-output Residox 750 with an integrated floor-level electronic sensor, providing unattended drainage in larger areas, deeper sumps, and applications where water has to be moved over distance or pumped uphill without an operator present. It offers the same convenience as the 400 Automatic, with significantly more pumping capacity behind it.

When to choose the 750 Automatic over the 400 Automatic

The 750 delivers 330 l/min and a 16-metre head, against 250 l/min and 11 m on the 400.

 The 750 Automatic is the appropriate choice when:
•    The sump or area being drained is larger or deeper
•    Water has to be discharged uphill to a drain, manhole or external chamber
•    The horizontal run from pump to discharge point is long
•    Faster drain-down is needed (for example, a lift shaft that must clear quickly)
•    The installation requires headroom for worst-case flood events

For smaller residential basements and standard plant-room duties, the Residox 400 Automatic is usually sufficient.

Why this is preferable to a float switch

Float switches require several centimetres of water to swing freely, which makes them poorly suited to puddle-pumping work. The Residox Automatic uses a small electronic sensor probe, hard-wired into the pump, which sits flat on the ground next to it. The probe detects water at 3 mm (±1 mm) above floor level, well below the level any float switch could reach.

Note that the operating cycle of an automatic pump is governed by the sensor, not the pump itself. The Residox 750 is mechanically capable of pumping water down to approximately 1 mm above the floor (as in the manual version), but in automatic operation the sensor will signal the pump to stop once the water level falls below the 3 mm trigger point. For jobs requiring water to be removed to the lowest possible level in a single pass, the manual Residox 750 is the more appropriate choice.

Plug in and run, no control panel required

The sensor is wired into the pump as a single unit, so no control panel, piggyback plug or external wiring is required. The pump plugs into a standard 230V mains socket and is ready to operate. Both the pump and the sensor probe are rated IP68 and fully submersible.

Adjustable Sensor Delay

The two delay times are one of the most significant practical advantages of this pump over float-switch alternatives.

The start delay (factory setting 5 seconds) requires the sensor to detect water continuously for the duration of the delay before the pump activates. Brief water events such as a splash, a momentary drip, or run-off from cleaning will dissipate before the delay expires, and the pump will not start. This prevents unnecessary cycling and reduces motor wear from reacting to non-events.

The stop delay (factory setting 30 seconds) keeps the pump running for the duration of the delay after the water level has fallen below the sensor. Without this delay, the pump would shut off the moment the water cleared the sensor and immediately restart as more water entered, producing a high frequency of short on/off cycles. Rapid cycling is one of the most common causes of premature motor failure in automatic pumps. The stop delay allows the pump to complete each pumping cycle fully before resting.

Both delays are adjustable from 1 to 120 seconds using the supplied magnetic key, held against the side of the sensor housing.

Important: do not run dry

Setting the stop delay too long will leave the pump running after the water has cleared, which damages the seals and shortens motor life. The factory 30-second setting is suitable for most installations. Increase the stop delay only when the pump has demonstrably more water to clear at that point in the cycle.

Suitable applications

•    Large basements and warehouse cellars with known ingress issues
•    Deep sump pits in facilities management and industrial sites
•    Lift shafts that need fast, automatic drain-down
•    Plant rooms and utility areas with longer discharge runs
•    Permanent passive flood defence in commercial and B2B settings

Less suitable for

Fast-flowing, turbulent or intermittent surface water (such as exposed external drainage where rainfall causes erratic level changes) can cause excessive cycling even with the delays in place. In these situations, the manual Residox 750 or a system with additional level controls is more appropriate.

Build, capacity and electrics

Full Residox build: cast iron pump housing, stainless steel outer case and handle, Hytrel vortex impeller, 2 mm free passage, and rubberised NBR base. The pump delivers 330 litres per minute with a 16-metre head. No priming is required (unlike a Tsurumi LSC, which needs water poured in before first use).

The automatic version is supplied as a 230V unit only. For 110V site use, the manual Residox 750 with a separately fitted control system is the appropriate alternative.

Key Features

✔ Integrated floor-level sensor, hard-wired into the pump 
✔ Detects water at 3 mm (±1 mm) above floor 
✔ Higher flow and head than the 400 Automatic (330 l/min, 16 m) 
✔ Adjustable delays prevent rapid on/off cycling, protecting the motor 
✔ Start delay 1 to 120 seconds (factory 5) 
✔ Stop delay 1 to 120 seconds (factory 30) 
✔ Plug straight into 230V mains, no control panel required 
✔ Pump and sensor both rated IP68 
✔ Full Residox build: cast iron, stainless steel, Hytrel impeller 
✔ 2 mm free passage, rubberised NBR base 
✔ 230V only, 1-year manufacturer's warranty

What's in the Box

✅ 1 x EVAK Residox 750 Automatic Puddle Pump with integrated floor-level sensor 
✅ 1 x Magnetic key for delay-time adjustment 
✅ 1 x 10m heavy-duty rubber power cable 
✅ 1 x 2 inch (50mm) hose tail

Optional: add a 90° elbow hose tail to prevent hose kinking and maintain optimum flow.