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 COIL — MC is ideal for direct electric operation during summer and can be switched to boiler operation during winter. MAXI COIL comes standard with a smooth-piped, scaleesistant heating coil with a capacity of up to 30 kW from the boiler. The electric immersion heaters have optional effect 5–15 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 kit and Vessel can be supplied.

Other sizes and specifications are available to order.

• Energy flexibility for summer / winter operation, or as back-up
• 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
ECO-HOTWATER – DHW from alternative energy


Mixing valve – See separate commercial add-ons
Thermostat – 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
Coil connection – 2 x 1” female BSP threads
Other connections – 4 x ¾” female BSP threads