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Numerous issues – 11kW Daikin Altherma 3

newhouse87 · 2023-03-16T04:32:58Z

HI, Just found this forum last night and some of the posters on here have better knowledge then i have found anywhere else. Don't understand alot of it yet but anyway i had 11kw daikin altherma3 low temp split installed last February and moved into the newbuild in June. Only since winter came i have noticed many issues. For past 3 months some rooms were not heating at all but in the last 2 weeks i have figured out stats were wired to wrong ufh loops, have that sorted now thankfully. Installer left me no paperwork and told me nothing about system. Im still thinking its not as efficient as it should be. Some rooms take up to5-7 hours to get up to 21degree setpoint from say19degrees. Only from reading this forum i think my dhw schedule is bit inefficient. DHW 7am 50deg,2pm 50deg, once a week at5am 60deglegionella cycle. All schedules are 2hours long i think. Reheat set point is at 45 so from reading here im thinking that's too high and may override my ufh flow too much. Im on weather dependent mode but yesterday was 11 degrees and my lwt was 32. Is that bit cold and maybe why my ufh slow? Also noticed my copper flow pipe from unit gets hot but i could go back into room 10mins later and its alot cooler, any reason for this? Apologies about all the questions but i had extreme bills in nov/dec and want to figure this out and this forum seems by far the most knowledagble. Using 70kwhs a day on cold days in a well insulated 2600sq ft bungalow seems bit much. Getting some big spikes especially at night time/early morning. Thanks again.

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Transparent

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11/04/2023 3:44 pm

Well I'm guessing that the temp sensor is positioned where it has access to the surrounding air, but isn't within the air-stream which gets drawn through the unit.

You'll need to place your sensor in a similar position.

out of the rain/frost
not directly touching a piece of metal casing

Perhaps the problem is that the Daikin sensor has 'come adrift' from its mountings, and is no longer able to accurately reflect the true air temperature.

Save energy... recycle electrons!

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newhouse87

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Topic starter 11/04/2023 3:51 pm

@transparent Would it just have the 1 sensor that gives me my digital reading on main screen because that said something like2degrees at 5am.

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Transparent

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11/04/2023 4:05 pm

I don't expect they'll use more than 1 temp sensor on the outside unit.

Look at your graph.
There are three areas of interest

The red sector is clearly below zero, which was probably the setting on your controller.

The BUH continues to operate in the amber sector...
... until the sensor reports that the ambient air temp is 5°C

Save energy... recycle electrons!

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newhouse87

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Topic starter 11/04/2023 4:11 pm

@transparent actually missed that graph was freezing, was only looking around 4am. hopefully so by changing setting to minus 4 it wont kick in. Thought it would only kick in if i was calling for heat and heat pump couldn't mange without the back up. Didnt envisage it ever kicking in tbh and def not when heat wasnt needed.

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11/04/2023 4:20 pm

Like any other domestic 'frost-stat', the BUH temperature system is there to protect your pipes from freezing.

It has no concept of whether 'heat is required or not'.

The key temperature is +4°C That's when the volume of the water is greatest.
If the water in your pipes has frozen and then melts, the point at which a 'burst' occurs is +4°C not 0°C

It's only safe to lower the set-point to -4°C if there's anti-freeze (ethylene glycol) in the mix.

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newhouse87

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Topic starter 11/04/2023 4:47 pm

@transparent oh yeah i get you now, the flow wasnt for loops just o keep stuff from freezing, do ye mean antifreeze in ufh water thats going to loops or antifreeze in some part of the unit, plumber or daikin installer, who would put it in just s i know who to ring?

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Derek M

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11/04/2023 6:51 pm

Posted by: @newhouse87

↑

@transparent oh yeah i get you now, the flow wasnt for loops just o keep stuff from freezing, do ye mean antifreeze in ufh water thats going to loops or antifreeze in some part of the unit, plumber or daikin installer, who would put it in just s i know who to ring?

To test if this is the cause of energy consumption, set the temperature down so that the heat pump stops, as you do with the overnight setback, then increase the Equilibrium Temperature setting above the present outside air temperature. There could be another sensor actually attached to the pipework, rather than the air temperature sensor, which is initiating the frost protection, so there may be a delay before it operates, since the pipework may have to cool down.

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Derek M

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11/04/2023 6:59 pm

@newhouse87

I forgot to mention. Have a look at the manual for the controller, there may be an icon on the controller display which indicates if the BUH is operating.

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newhouse87

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Topic starter 11/04/2023 7:18 pm

Posted by: @derek-m

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Posted by: @newhouse87

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@transparent oh yeah i get you now, the flow wasnt for loops just o keep stuff from freezing, do ye mean antifreeze in ufh water thats going to loops or antifreeze in some part of the unit, plumber or daikin installer, who would put it in just s i know who to ring?

To test if this is the cause of energy consumption, set the temperature down so that the heat pump stops, as you do with the overnight setback, then increase the Equilibrium Temperature setting above the present outside air temperature. There could be another sensor actually attached to the pipework, rather than the air temperature sensor, which is initiating the frost protection, so there may be a delay before it operates, since the pipework may have to cool down.

so do you mean set equilibrium temperature to like 10deg overnight? Would that not mean its v likely to come on then? I can look at actuators in sensors settings when heat pump is running, i looked this morning and pump and compressor were def on and i think buh said on aswell, if it happens again i will know to look out for it. NO icon on manual for buh active.

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Derek M

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11/04/2023 7:58 pm

@newhouse87

No, I didn't mean set the ET to 10C overnight, I meant to try the test now before you go to bed. Initiate a setback so that the heat pump is stopped, then increase the ET setting to see if the problem reappears. By doing so you will know if this is the cause of the problem.

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newhouse87

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Topic starter 11/04/2023 8:09 pm

@derek-m just changed it 5 minutes ago, no start of the pump yet anyway. Is it antifreeze in ufh water or actual unit you were talking about?

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Derek M

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11/04/2023 8:14 pm

Posted by: @newhouse87

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@derek-m just changed it 5 minutes ago, no start of the pump yet anyway. Is it antifreeze in ufh water or actual unit you were talking about?

Unless you have a heat exchanger in your system, it is the same water that flows around the heating system, through the heat pump and through the UFH pipework.

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