Posted by: @johnboy

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@mike-h - can you possibly point me towards any advice on how to install iBoost with a Samsung Gen 6 ashp? I have searched the forums, but can't find out whether to wire iBoost directly to the immersion, or disconnect immersion from Samsung, before connecting iBoost? Flumoxed (I have a qualified electrician trying to sort this for me). Thanks in advance 😁

Hi, the immersion was disconnected from Samsung and the iBoost directly connected to the immersion instead. Therefore there is no connection between the Samsung and the iBoost. You can set it to do your legionella sterilisation at periodic intervals should you wish, so there is no loss in functionality.

Many thanks@mike-h - so disconnect the immersion from the Samsung, and connect the iBoost directly to the immersion.. Can I assume that the Samsung won't throw an error message, when it can't find an immersion connected e.g. during the legionella cycle? (Many thanks for your time 🙂)

Posted by: @johnboy

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Can I assume that the Samsung won't throw an error message, when it can't find an immersion connected e.g. during the legionella cycle?

I would disable the legionella sterilisation (FSV 3041) and there shouldn't be any error messages then. I don't have any.

Thanks @mike-h - I am hugely grateful for the information 😃👍

@mike-h as an alternative, instead of turning off the legionella altogether, does the CP allow you to change the set point temperature for legionella cycles? You could then, for example, change that to 10C, so the heat pump would always be "satisfied".

The minimum set point for legionella on the Samsung is 40C, so this would not work. However, I don't follow your logic in looking for an alternative to turning legionella off on the Samsung. The Samsung has to be disconnected from the immersion. The iBoost takes over all immersion heating, whether from excess solar power or should you wish to do so, from the grid.

Isn't it more efficient/cheaper to heat your DHW with the ASHP with a COP of 3 (300% efficiency) than use the immersion with a COP of 1?

Excess solar isn't "free", it has a cost/value and that is the amount your provider is paying you for any exported energy. For me, on Octopus Fixed export, that's 15p/kWh. On tariffs such as Agile or Cosy, I can reheat my tank for a unit price similar to the 15p Octopus will pay me for exported excess solar.

To reheat my DHW cylinder currently requires ~4kW. Using an immersion at 100% efficiency that uses 4kW of electricity. Using the ASHP currently uses around 1.25kW of electricity with a COP of 3.2.

If I schedule reheating during warmer times of the day when the ASHP is more efficient, most of that 1.25kW is covered by solar anyway. I've used less energy and haven't had to purchase more equipment. I don't understand the logic of using a solar diverter to run an immersion to heat DHW where an ASHP is installed and is 3 times more efficient. What am I missing?

@mike-h speaking as somebody who had an iBoost but didn't know how to install it with a Gen 6 - many thanks for your help. [And please accept my apologies if I have inadvertently reignited the old 'PV diverter vs. using the ashp' debate at the same time😁]

@old_scientist I am on FIT and get 9p/kWh generated. The main financial benefit from my solar panels is from not using the grid, especially at expensive times. Hence the Solar iBoost is saving me money, but I accept that it is not the best use of resources. Ideally, if the Samsung could be persuaded to produce 3kW to heat the DHW, instead of 5kW, then with a COP of 3, my solar production might cover the electricity consumption of 1kW. In reality, I don't get a COP of much more than 1.8 (albeit in winter, not summer temperatures).

I will experiment with using the Samsung to heat DHW and see what the figures look like.

Posted by: @johnboy

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apologies if I have inadvertently reignited the old 'PV diverter vs. using the ashp' debate at the same time

@johnboy No problem at all. I had never heard of this 15p fixed export tariff until recently, so it is all good to know.

Posted by: @mike-h

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@old_scientist I am on FIT and get 9p/kWh generated. The main financial benefit from my solar panels is from not using the grid, especially at expensive times. Hence the Solar iBoost is saving me money, but I accept that it is not the best use of resources. Ideally, if the Samsung could be persuaded to produce 3kW to heat the DHW, instead of 5kW, then with a COP of 3, my solar production might cover the electricity consumption of 1kW. In reality, I don't get a COP of much more than 1.8 (albeit in winter, not summer temperatures).

I will experiment with using the Samsung to heat DHW and see what the figures look like.

Posted by: @johnboy

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apologies if I have inadvertently reignited the old 'PV diverter vs. using the ashp' debate at the same time

@johnboy No problem at all. I had never heard of this 15p fixed export tariff until recently, so it is all good to know.

 

@mike-h I have been running my Samsung gen 6 (12kW) in Quiet Mode for scheduled DHW cycles for exactly that reason - it limits the power of the ASHP to around 3.3kW max, and the vast majority of the run is below 3kW with only the last few mins peaking above 3kW. On a sunny day, with the full 3kW output from my inverter, I can cover the vast majority of this on solar assuming nothing much else is running. I normally reheat during the cheapest afternoon slot on Octopus Agile (often at 2:30pm)