Hello, I have a DAIKIN ERSQ 011AAV1 16KW. I have a BRC21A52 controller and there is a code in the service manual 9-02 that is indicated as Thermo on/off admission with a range -5 till +5. Does anyone what exactly does it do? For example what's the difference between setting it at +5 and -5? There is also another code 9-03 that the step is every 0.2 and it can be set either until +5 or -5 but there isn't any explanation in the manual what is this code about. Any help would be nice. Thank you in advance.
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Daikin high temperature heat pump
Best answer by karas21
Hello. I sent an enquiry to Daikin.co.uk and that was their response.
The field settings you're referring to (accessed via the BRC21A52 wired remote controller in service mode) are part of the [9] group for automatic temperature compensation in Daikin Altherma high-temperature systems like your ERSQ016AAV1. These allow fine-tuning of thermistor readings and control logic by applying correction values to compensate for temperature differences or system behavior. The ranges and steps may vary slightly by firmware or regional manual, but based on the service documentation for this series, here's the breakdown:
[9-02]: Thermo ON/OFF Admission
- Description: This setting defines the temperature compensation or hysteresis (deadband) for the thermostat's ON/OFF control logic. It adjusts the threshold at which the system admits (allows) operation based on measured temperatures (e.g., leaving water or ambient). Essentially, it prevents short-cycling by creating a buffer around the setpoint where the system won't toggle on/off unnecessarily. Positive values make the system less sensitive (higher threshold for activation), while negative values make it more sensitive (lower threshold).
- Range: -5°C to +5°C
- Step: Typically 1°C (though some variants allow 0.5°C increments, aligning with your example).
- Default: 0°C (no compensation; standard logic).
- Difference between +0.5 and -0.5:
- +0.5°C: Increases the activation threshold. For example, in heating mode, the system might require the temperature to drop 0.5°C below the setpoint before turning ON, and it turns OFF at or above the setpoint. This delays activation for stability in milder conditions.
- -0.5°C: Decreases the activation threshold. The system turns ON sooner (e.g., at 0.5°C above the setpoint drop) and may stay ON longer. This is useful for quicker response in colder or more demanding conditions but risks more frequent cycling.
[9-03]: (Likely Domestic Hot Water Tank Compensation Value or Related Offset)
- Description: This code is not always explicitly detailed in user-facing manuals but appears to be a fine adjustment for temperature compensation, possibly related to the domestic hot water (DHW) tank thermistor or a secondary hysteresis/offset for room or water temperature control. It applies a correction to measured values to align with actual conditions, affecting when the system engages for DHW or space heating.
- Range: -5°C to +5°C
- Step: 0.2°C (as per your description; this allows precise tuning).
- Default: 0°C.
- Purpose: Similar to [9-02], it compensates for discrepancies (e.g., sensor placement or pipe losses). Positive values raise the effective setpoint, negative lower it. Without explicit manual explanation, it's often left at default unless calibration shows inaccuracies.
[9-04]: (Likely Thermo ON/OFF Admission or Time-Related Delay)
- Description: This setting is tied to the thermo ON/OFF logic, potentially as an additional hysteresis or a time-based parameter for admission (e.g., minimum runtime or delay before ON/OFF to avoid rapid switching). In some contexts, it's a compensation value like the others, but your step/range suggests it may be a timer (e.g., anti-short-cycle delay in minutes). It ensures stable operation by delaying state changes.
- Range: Up to 60 (likely minutes if time-based; or -5°C to +5°C if temp-based like the others).
- Step: 10 (e.g., 10, 20, 30...60).
- Default: 0 or model-specific.
- Purpose: If temperature-based, similar to [9-02] for finer control. If time-based (matching your step/until 60), it sets a delay period for thermo transitions, preventing wear from frequent starts/stops.
Hello, I have a DAIKIN ERSQ 011AAV1 16KW. I have a BRC21A52 controller and there is a code in the service manual 9-02 that is indicated as Thermo on/off admission with a range -5 till +5. Does anyone what exactly does it do? For example what's the difference between setting it at +5 and -5? There is also another code 9-03 that the step is every 0.2 and it can be set either until +5 or -5 but there isn't any explanation in the manual what is this code about. Any help would be nice. Thank you in advance.
The step in code 9-02 is every 0.5. Either +0.5 or -0.5
+9- Super User
Good morning
Out of curiosity I went and got the manual and had a look for the word ‘admission’ because it puzzled me and it seems that the word has the same meaning as ‘hysteresis’ which is the dead band that you can set where the system will temporarily not operate if the temperature is within the band. Have a look at the explanation below from page 109.
In most instances it's best to have the hysteresis set to zero for a heating or a cooling only system.
However, when you have heating and cooling available at the same time you don't want the cooling to come on immediately after the heating has gone off as it will just oscillate between the two wasting energy. Instead you set an admission (hysteresis) value greater than zero so you create a dead band in the middle where the system does nothing until it hits either the top value and starts cooling or the bottom value and starts heating. That seems to be what it's about.
The manual is here but it may not be the right one but it does explain the term.
https://www.manualslib.com/manual/606303/Daikin-Room-Air-Conditioners.html
Peter
Thank you for your answer. I have that manual and have read the same thing from code 9-02. I just couldn't understand what exactly does this mean. I have the heat pump just for heating (radiator panels). I have it functioning with a weather curve and settling the thermostat in my house at 21°C. I have tried setting the 9-02 at +0,5 some days and -0,5 other days. But to be honest I can't understand if there is a difference in the heat pump function. That's why I asked here in case anybody have the same heat pump or have tried something similar in their heat pump with a code like this I mentioned.
Also, the code 9-03 that my controller has, is not mentioned in the manual. Maybe something similar to the code 9-02? I don't know.
+4
I’m glad to see
If you do contact them and get an answer we’d appreciate you letting us know what they say on the Forum, as it could help others with the same question in future - cheers 😁.
+8I have a different Daikin to you (EHBH-E6V) but it’s possible that the same codes are used throughout all Daikin’s products. In the installer reference manual for mine the code 9-03 refers to a cooling minimum setpoint for LWT. Default is 5deg. 9-02 is the cooling maximum set point, default is 22deg again this is for my system!
You could ask the question on the renewableheatinghub forum as they have installers on there.
Hello. I sent an enquiry to Daikin.co.uk and that was their response.
The field settings you're referring to (accessed via the BRC21A52 wired remote controller in service mode) are part of the [9] group for automatic temperature compensation in Daikin Altherma high-temperature systems like your ERSQ016AAV1. These allow fine-tuning of thermistor readings and control logic by applying correction values to compensate for temperature differences or system behavior. The ranges and steps may vary slightly by firmware or regional manual, but based on the service documentation for this series, here's the breakdown:
[9-02]: Thermo ON/OFF Admission
- Description: This setting defines the temperature compensation or hysteresis (deadband) for the thermostat's ON/OFF control logic. It adjusts the threshold at which the system admits (allows) operation based on measured temperatures (e.g., leaving water or ambient). Essentially, it prevents short-cycling by creating a buffer around the setpoint where the system won't toggle on/off unnecessarily. Positive values make the system less sensitive (higher threshold for activation), while negative values make it more sensitive (lower threshold).
- Range: -5°C to +5°C
- Step: Typically 1°C (though some variants allow 0.5°C increments, aligning with your example).
- Default: 0°C (no compensation; standard logic).
- Difference between +0.5 and -0.5:
- +0.5°C: Increases the activation threshold. For example, in heating mode, the system might require the temperature to drop 0.5°C below the setpoint before turning ON, and it turns OFF at or above the setpoint. This delays activation for stability in milder conditions.
- -0.5°C: Decreases the activation threshold. The system turns ON sooner (e.g., at 0.5°C above the setpoint drop) and may stay ON longer. This is useful for quicker response in colder or more demanding conditions but risks more frequent cycling.
[9-03]: (Likely Domestic Hot Water Tank Compensation Value or Related Offset)
- Description: This code is not always explicitly detailed in user-facing manuals but appears to be a fine adjustment for temperature compensation, possibly related to the domestic hot water (DHW) tank thermistor or a secondary hysteresis/offset for room or water temperature control. It applies a correction to measured values to align with actual conditions, affecting when the system engages for DHW or space heating.
- Range: -5°C to +5°C
- Step: 0.2°C (as per your description; this allows precise tuning).
- Default: 0°C.
- Purpose: Similar to [9-02], it compensates for discrepancies (e.g., sensor placement or pipe losses). Positive values raise the effective setpoint, negative lower it. Without explicit manual explanation, it's often left at default unless calibration shows inaccuracies.
[9-04]: (Likely Thermo ON/OFF Admission or Time-Related Delay)
- Description: This setting is tied to the thermo ON/OFF logic, potentially as an additional hysteresis or a time-based parameter for admission (e.g., minimum runtime or delay before ON/OFF to avoid rapid switching). In some contexts, it's a compensation value like the others, but your step/range suggests it may be a timer (e.g., anti-short-cycle delay in minutes). It ensures stable operation by delaying state changes.
- Range: Up to 60 (likely minutes if time-based; or -5°C to +5°C if temp-based like the others).
- Step: 10 (e.g., 10, 20, 30...60).
- Default: 0 or model-specific.
- Purpose: If temperature-based, similar to [9-02] for finer control. If time-based (matching your step/until 60), it sets a delay period for thermo transitions, preventing wear from frequent starts/stops.
+9- Super User
A really interesting reply. Thank you.
[9-02] I'm pleased they used the term hysteresis as being equivalent admission. At least that says age hasn't completely fried my brain.
But what surprises me is that they seem to be guessing what [9-03] and [9-04] are and they are supposedly the manufacturers. I wonder if this is a Chinese boiler which was produced to a generic spec and is badged Daikin. Who knows?
Peter
I replied to this email and asked about code 9-03 and 9-04 but they replied (maybe another one replied) that these codes are meant to be used by an expert so no possible damage can happen if I try to do something. So they suggested that I should call an expert at my house.
I thought that I could do some settings through these codes so my heat pump doesn't start functioning if the thermostat in my house drops by 0.1. But I don't think I manages to change it. I set at 9-02 (+0.5), at 9-03 (+0.2) and at 9-04 (20)
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