Advice please on controls for my Daikin 14kw 3H HT heat pump with 3H HT W internal unit and Megaflo cylinder

JoninOrkney · 2024-09-13T12:14:37Z

Hello. I live in an old stone house in Orkney and have just had a Daikin high temperature heat pump installed. The whole heating system is new, including radiators that are sized as if for a regular gas boiler. Finding a local installer willing to quote and then to start work proved difficult and I used the largest electrical contractor on the island. The installation went badly wrong when the plumber who designed the system went off sick, and it has taken a year for them to finally get the system working properly without constantly cutting out. I could write many pages about the saga of the installation, but my worry now is that the system is not running as efficiently as it should, and we have some of the highest electricity charges in the UK here despite being self-sufficient in renewables. I asked the plumber (the original one after he returned to work) about setting a weather-dependent curve, and he told me that with a high temperature pump this is not needed, so the flow temperature is set at a constant 60 degrees. The controls are TRVs on the radiators and an old-fashioned time switch and thermostat on the wall in the hallway just inside the front door. The thermostat seems to work like an on-off switch - the radiators are either hot or cold. I have not yet tried to fine-tune the TRVs as the heating isn't used constantly yet. As it is an old stone house it would seem to be better to run the heating for longer at a lower temperature, but most of the advice that I have seen is not for high temperature heat pumps. Ideally I would like an independent heating engineer with experience of Daikin pumps to advise me on how the heat pump could be made to run more efficiently, but as I live on Orkney this doesn't seem to be an option. So I would be grateful for any help that members of this forum can provide.

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JoninOrkney

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Topic starter 15/09/2024 5:05 pm

@johnmo Hello johnmo. The radiators used to go cold and when I checked the indoor unit the panel showed an error code. Before they did more work on it around last Christmas there were sometimes two errors, and it was difficult to get it to start on a couple of very cold mornings. After that it was usually a flow sensor malfunction code. Pressing reset usually fixed it for a while, but it did sometimes cut out 5 times a day. After they removed the extra circulation pump at the end of May this year there were no more errors and I have never had to re-set it.

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Anonymous 5011

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15/09/2024 5:25 pm

That's a low flow condition. Do you have lots of zones (thermostats) if so what's happening is the zones are closing off, and the circulation pump cannot get enough water through the system.

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JoninOrkney

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Topic starter 15/09/2024 5:43 pm

@johnmo Hello again johnmo. That's no longer a problem, as removing the unnecessary pump has now fixed it. My question was whether the plumber was correct in saying that I don't need a weather compensation curve, and the advice that I have had on here so far suggests that I do. The time switch, that he set for twice a day like a gas boiler, and the thermostat inside the front door controlling the whole system also don't seem to be very sophisticated.

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Anonymous 5011

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15/09/2024 5:48 pm

Posted by: @joninorkney

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@johnmo Hello again johnmo. That's no longer a problem, as removing the unnecessary pump has now fixed it. My question was whether the plumber was correct in saying that I don't need a weather compensation curve, and the advice that I have had on here so far suggests that I do. The time switch, that he set for twice a day like a gas boiler, and the thermostat inside the front door controlling the whole system also don't seem to be very sophisticated.

Low and slow is best, running like a gas boiler you will need a second mortgage. So weather compensation is best

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