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Nibe 8kW F1145, Isle of Skye, Scotland

Ground Source Heat Pump (GSHPs)

Last Post by Derek M 4 years ago

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Donald

(@donald)

New Member Member

Joined: 4 years ago

Posts: 2

Topic starter 27/02/2022 10:17 pm [#337]

Hi Mars,

Many thanks for creating such a useful site and I only wish it had been in existence 12 years ago while I was researching my own new build project here on the Isle of Skye in the often chilly west coast of Scotland.

So, I finally had installed in 2012 a Nibe 8kW F1145 connected to 2 vertical boreholes each 80m deep, and the system continues to perform well.The 4-bedroom house has a floor area of 170 sqm with underfloor heating throughout. It has taken me a long time to become familiar with the system and I'm still learning, but the investment of time and energy is essential to continually check that it works as it should and to avoid scary electricity bills.

So, the heat pump is connected to a Nibe 300-litre DHW cylinder with 400-litre buffer tank for the UFH. I find the heating curve (weather compensation) settings work fine and I make sure that all the room thermostats for the UFH are fully open so that the heating curves fully control the system.

System 1 (buffer tank) is set to Curve 4 and System 2 (UFH) to Curve 3 and this maintains a comfortable indoor temperature of 21 degrees C with a corresponding System 1 and System 2 flow temperature today 27 Feb, with outdoor temp of 8 degrees C, of 27 and 25 degrees C respectively. The F1145 has a stated COP of 3.55 and its annual consumption is 9,248 kWh which averages as 25 kWh per day.

I hope that the detail here is helpful to anyone else currently in the research phase. However, I strongly agree with others that the first priority must always be in ensuring the optimum energy efficient design and construction of the house, especially around the windows and insulation. My house has quite a lot of glazing - 5 sliding patio doors and 12 velux roof windows - and the Rationel windows are excellent and draught-free, but you do have to be careful with the glass as it tends to scratch easily even when undertaking normal cleaning.

Thanks for reading this far, and good luck.

👍

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Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 4724

28/02/2022 5:27 pm

Welcome to the forums @donald and thank you for sharing your sharing your positive experience and for reminding is that heat pumps can work when designed and installed correctly. It's also heartening to hear your system is now 10 years old and going strong. The other thing that leapt out at me is the 400 litre buffer store - that's massive, or is that standard for GSHP systems? What is the approximate footprint of your property that you're heating?

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Donald

(@donald)

New Member Member

Joined: 4 years ago

Posts: 2

Topic starter 28/02/2022 9:24 pm

Many thanks, Mars and my mistake - my Nibe 300/450 VPAS DHW cylinder in fact incorporates a 450-litre buffer tank. I hadn't realised that this was overly big, but does indeed appear to be excessive married to my 8kW GSHP.

I should have added that I also have a 5kW roof-mounted solar thermal connected to the bottom coil of this cylinder but my RHI application for the solar thermal was rejected as with this tank set-up, the solar cannot be deemed to be providing renewable heat exclusively for the DHW.

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