The MAXI series is the class-leading commercial range of hot water calorifiers, built to the high standards of design and efficiency that is synonymous with OSO Hotwater products. The MAXI range has been manufactured with EVERLAST™ high-alloy stainless steel in combination with ULTRAWELD™ technology for optimal corrosion resistance. Not only is the MAXI range extremely efficient, with industry-leading performance, it can also be modified according to customer requirements.

MAXI XPRESS — MX boasts twice the available immersion heater capacity as the standard, is heated either with the integrated electric INCOTEC immersion heaters, or via an external energy source and the TURBOSYSTEM with plate heat exchanger (optional capacity) and double sets of pumps for extra operational safety. The electric immersion heaters has optional effect 5–30 kW, 230–400 V + N 3-phase, and is thermostat controlled 60–90 °C in three steps with separate safety thermostats. Contactors are not required and the support cable is connected directly to the central.

G3 Kits and expansion vessel as standard

Other sizes and specifications are available to order.

• Extreme operational durability with el. heaters w/o contactors
• 10 bar design pressure and class-leading corrosion resistance


NANOPUR – Class-leading insulation (300/400 L)
ISOFLEX+VIP – Class-leading insulation (600/1000 L)
ULTRAWELD – Superior corrosion resistance
INCOTEC – High durability in hard water
MAXTEMP – Solar / hot water connection
SOLAR-READY – Separate solar connection


Mixing valve – See separate commercial add-ons
Thermostats – Adjustable 60-90°C – Preset 75°C
Safety valve – TP 9 bar/99°C – 3/4” to drain
Flow/ret. conn. – 2 x 1-½” female BSP threads
Other connections – 4 x ¾” female BSP threads

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Specifications Unit MX 400 15+15 kW/3x230VMX 600 15+15 kW/3x230VMX 1000 15+15 kW/3x230V
Product no. OSO 800165280016528001654
Product name MX 400 15+15 kW/3x230VMX 600 15+15 kW/3x230VMX 1000 15+15 kW/3x230V
Usage Hot WaterHot WaterHot Water
Placement FloorFloorFloor
Diameter — ⌀ mm 5957801000
Height - H mm 222519102115
Weight kg 85139244
Packaging mm xxxxxx
Freight Volume dm3
Technical / ErP information
Capacity Persons
Capacity 40C L
Volume L 400600885
Thermostat set point C 606065
Heat loss - EN 12897 Watt 103120142
Heat loss / 24 hrs - EN 12897 kWh/day 2.472.88
AEC (energy consumption) kW/year
Energy efficiency %
Tapping profile 3XS–XXL
Energy rating A+–F CCC
Primary Heating Power kW
Heat-up time ΔT 55°C Coil Mins
Heat-up time ΔT 55°C upper element Mins
Heat-up time ΔT 55°C lower element Mins
Recovery time ΔT 55°C coil 70% Mins
Recovery time ΔT 55°C upper element 70% Mins
Recovery time ΔT 55°C lower element 70% Mins