Switching On Your Hot Water Immersion
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What Does This Mean?
Most heat pump systems include an immersion heater inside the hot water cylinder. It’s like a large kettle element that heats water with electricity. Turning it on gives you a backup way to heat water if your heat pump is off or not producing hot water.
Why Would You Do It?
- If your heat pump isn’t heating water.
- To make sure you still have hot water while waiting for a repair.
Switching on the Immersion – Vaillant AroTHERM Plus & Grant R290 Heat Pumps.
- Find the Immersion Switch: Usually a wall switch or fused spur near your hot water cylinder, sometimes labelled “Immersion” or “water heater”.
- Turn the Switch to ON: A small light may glow to show it is heating.
- Wait for Water to Heat: It may take 2 hours to fully heat the cylinder.
- Switch Off When Finished: Immersions use a lot of electricity – only keep it on as long as needed.
Switching on the Immersion – Mitsubishi Ecodan Controller FTC 5 /6
- Go to Mitsubishi controller, press any button to light up the screen. when lit up you should be on the home screen.
- Press the menu button (bottom left round button).
- Scroll to the furthest right service menu and press the tick button.
- The code is 0000, press the tick button again.
- Scroll down to heat source setting, press the tick button.
- System shut down message will show up, press yes.
- Press the button below the yellow circle symbol to change the setting to heater and press the tick button.
- Press return button to go back to home screen with the date and time.
- Press the power button on the bottom right, system will start again, and lightning bolt symbol will appear on the screen.
Mitsubishi Ecodan Touch Screen FTC 7
Follow the same procedure as above but be aware that the controller is all touch screen so button selection will be done on the screen.
Switching on the Immersion – Samsung Generation 7 Heat Pumps with Generation 6 controller
- Wake up main controller by pressing the okay button in the middle
- Press the plus and minus buttons together for 5 seconds
- Enter code 0202 to access service menu
- Scroll down to self-test mode and press okay
- Scroll down to booster heater and scroll right to turn on
- Leave the controller on this screen for as long as you want the immersion to heat the water.
- Immersion heater has a thermostat so will only heat the water when temperature drops inside the cylinder.
When to Call Us
- If you need to use the immersion (the heat pump may not be working correctly).
- If no hot water is produced even with the immersion switched on.
- If the immersion switch or wiring feels hot, smells, or looks damaged.
- If you’re unsure where the immersion switch is or how to use it safely.
Tip: The immersion is for backup and occasional use, not for everyday hot water heating.
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At a glance
What Does This Mean?
Most heat pump systems include an immersion heater inside the hot water cylinder. It’s like a large kettle element that heats water with electricity. Turning it on gives you a backup way to heat water if your heat pump is off or not producing hot water.
Why Would You Do It?
- If your heat pump isn’t heating water.
- To make sure you still have hot water while waiting for a repair.
Switching on the Immersion – Vaillant AroTHERM Plus & Grant R290 Heat Pumps.
- Find the Immersion Switch: Usually a wall switch or fused spur near your hot water cylinder, sometimes labelled “Immersion” or “water heater”.
- Turn the Switch to ON: A small light may glow to show it is heating.
- Wait for Water to Heat: It may take 2 hours to fully heat the cylinder.
- Switch Off When Finished: Immersions use a lot of electricity – only keep it on as long as needed.
Switching on the Immersion – Mitsubishi Ecodan Controller FTC 5 /6
- Go to Mitsubishi controller, press any button to light up the screen. when lit up you should be on the home screen.
- Press the menu button (bottom left round button).
- Scroll to the furthest right service menu and press the tick button.
- The code is 0000, press the tick button again.
- Scroll down to heat source setting, press the tick button.
- System shut down message will show up, press yes.
- Press the button below the yellow circle symbol to change the setting to heater and press the tick button.
- Press return button to go back to home screen with the date and time.
- Press the power button on the bottom right, system will start again, and lightning bolt symbol will appear on the screen.
Mitsubishi Ecodan Touch Screen FTC 7
Follow the same procedure as above but be aware that the controller is all touch screen so button selection will be done on the screen.
Switching on the Immersion – Samsung Generation 7 Heat Pumps with Generation 6 controller
- Wake up main controller by pressing the okay button in the middle
- Press the plus and minus buttons together for 5 seconds
- Enter code 0202 to access service menu
- Scroll down to self-test mode and press okay
- Scroll down to booster heater and scroll right to turn on
- Leave the controller on this screen for as long as you want the immersion to heat the water.
- Immersion heater has a thermostat so will only heat the water when temperature drops inside the cylinder.
When to Call Us
- If you need to use the immersion (the heat pump may not be working correctly).
- If no hot water is produced even with the immersion switched on.
- If the immersion switch or wiring feels hot, smells, or looks damaged.
- If you’re unsure where the immersion switch is or how to use it safely.
Tip: The immersion is for backup and occasional use, not for everyday hot water heating.