The IMM01 Immersion Heater Power Halver is designed to halve the power consumed by standard 1-2kW 230V AC immersion heaters. (It is not suitable for 3kW immersion heaters). When using the IMM01, the 1kW heater effectively becomes 500W. In a marine application, this ensures the current consumption limit from the mains when a boat is moored is not exceeded. The device is rated at 240V, 8A. The device is simply connected in series with the immersion heater, and to bypass the IMM01, a switch can be connected across the module. The IMM01 possesses thermal and over-current protection and is hermetically sealed in epoxy resin in an ABS enclosure.

1kW and 2kW Standard fitting immersion heaters are available from Brian Ward Electrical

Please note the unit is designed for marine applications and is NOT designed to be used with quasi-sine or pro-sine inverters, or generators.

The IMM01 is sealed in resin in an ABS enclosure and should be mounted on an earthed metal chassis to allow heat dissipation and electrical safety. The metal bracket is internally isolated from mains voltages, but should still be earthed. The module will run warm when operating, and an internal thermal cut-out is provided at 98°C to prevent excessive heat build-up. If this thermal cut-out ever trips, the IMM01 will need to be replaced.

The module can be bypassed (i.e. full power to the heater) simply by connecting a suitably rated switch ACROSS the red lead-outs. When the switch is closed, full power is allowed to flow to the heater, but when open the IMM01 takes over and allows half the power to the heater. The IMM01 should be supplied from a switched supply fused at 10A or less. Due to the halving of the power to the immersion heater when the IMM01 is operating, the water in which it is submersed will take twice as long to heat to the same temperature. The current drawn by a 1kW immersion at 240V reduces from 4.5A to about 2.3A when the IMM01 is operating. Please note cascading two or more IMM01 modules will not quarter the power, and the module will only work at AC voltages.

IMM01 Specifications

Parameter	IMM01	Comment
Datasheet
Nominal Supply Voltage	240V AC
Nominal Supply Voltage Range	100 - 450V AC
Maximum Heater Current	8A
Non-Sustained Peak Output Current	20A	< 3sec
Maximum Load	2kW
Operating Temperature Range	-20 - 98°C (-4 - 208°F)
Dimensions	52 × 52 × 31mm	L × W × H excl. fixings
Mechanical Fixing	2× 5.2mm dia, 20mm pitch
Electrical Connection	Wire-ended, 2x 30cm
Enclosure Style	Epoxy Potted ABS

IMM01 Typical Connection Diagram