How to I switch on backup on my SI--, LA--ME, LA--MS, LA--TU heat pump (not LA-MI) to get hot water in the event of a fault?

Modified on Tue, 29 Nov 2022 at 02:09 PM

If your heat pump has the following type of controls, then this will describe how to bring on the backup immersion in the event of a fault with the heat pump.

Press the MODE or MODUS button repeatedly until the screen shows “2nd heat generat.” on screen. After a few seconds, the square indicator block along the top of the screen will move all the way to the right below the 2nd heat generator symbol (3 wavey lines) to show it has switched to the backup mode.

This should then power on the immersion element within the hot water cylinder and, depending on the installation, may also switch on the buffer tank immersion element to provide some frost protection to the heating circuit. Where an oil/gas boiler is installed alongside the heat pump and is interconnected, the “2nd heat generat” mode may call for the boiler to provide that backup heat.

If no hot water is produced after a few hours, it could be that the hot water immersion element is not directly controlled by the heat pump. There may be an external switch or timer wired back to the hot water immersion element that needs to be switched on to get the backup immersion to run. Your installer would be able to advise how the immersion was wired in that case.

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