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Mitsubishi Ecodan & Raspberry Pi automations

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(@kev-m)
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Derek, that's probably quite easy to do because there is plenty of space inside the thermistor box.  Could the resistors be put upstream of the screw connectors or even outside the box?

20221220 120601

 


   
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(@derek-m)
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Posted by: @kev-m

Derek, that's probably quite easy to do because there is plenty of space inside the thermistor box.  Could the resistors be put upstream of the screw connectors or even outside the box?

20221220 120601

 

Hi Kev,

Yes, quite easily. One resistor would be connected directly across the two terminals. Then one of the wires, red or white, would be disconnected from its terminal and put into a connector block. The second resistor is then installed from the connector block to the terminal from which the wire was disconnected. Simples.

 


   
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(@ajdunlop)
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Thanks @derek-m . I don't think we have that separate thermostat so I'm not sure where the HP is getting the room temperature from on our office system. Is there another temp sensor in the FTC6 itself?

 

I've been trying to get my head around the different settings related to room and flow temperatures (default values in square brackets):

Operation settings -> 

    Heating operation*8 ->
        Flow temp.range *10 ->
            Min.temp. (25 - 45°C) [30]
            Max.temp. (35 - 60°C) [50]
    Room temp.control ->
        Mode (Normal/Fast)*13 [Normal]
        Interval (10 - 60min) [10min]
    Heat pump thermo diff adiust ->
        On/Off *6 [On]
        Lower limit (-9 - -1°C) [-5]
        Upper limit (+3 - +5°C) [5]

Notes:

*6 On: the function is active; Off: the function is inactive.
*8 Valid only when operating in Room temp. control mode.
*10 Valid only when operating in Heating room temperature.
*13 When DIP SW5-2 is set to OFF, this function is active.

Screenshot 2022 12 24 at 11.02.20
Screenshot 2022 12 24 at 11.02.47

Can varying the Flow Temp Range Min and Max make quite a difference to the performance of auto-adapt at least to start with? Would seem like the default min temperature is a bit high.

What exactly is the Room temp control Interval? Should it correspond to how laggy the heat emitter is, so that the controller doesn't keep ramping things up when it should expect this to take longer for things like UFH?

For the termo diff adjust, again I'm not completely sure what effect changing these values would have. Could the upper limit being too low cause the unit to cycle lots, especially if delta-T is too small? For the minimum I assume reducing this would cause the unit to take longer before heating again as the temp would have to drop further which could be good to reduce cycling too fast but could let things drop too much causing the unit to work harder to recover the temp.

Let me know if I have understood these settings correctly and what your real world experience is of adjusting them.

 


   
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(@derek-m)
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@ajdunlop

I don't have an Ecodan, so I have to make assumptions as to what function the various setting parameters perform.

Flow temp, range *10 - min & max.

I assume that these settings limit the range over which the heated water coming out of the heat pump can be controlled.

Room temp.control.

As you are no doubt aware there are various modes in which the heat pump can be operated, room temperature control being one of them.

The 'normal/fast' setting is fairly obvious, and would appear to be a course control for how quickly the controller can vary the water flow temperature. I suspect that it may be as simple as to allow the controller to raise or lower the calculated water flow temperature by 1C during each 'interval' when in 'normal' mode, and by 2C when in 'fast' mode.

I am not 100% certain about the 'interval' parameter. I suspect it may be used with the 'normal/fast' setting as described above.

 Heat pump thermo diff adjust.

Once again the description in the manual is rather vague. Obviously, when set to 'On' the lower and upper limits will be applied, but when switched to 'Off' does this mean that no limits are applied, so the temperature can be varied without limit, or does it mean that the temperature is not allowed to be varied?

The fact that it states 'adjust' in the title, could mean that it is limiting the range of adjustment that can be made by the user, or conversely by the controller. Also I can only assume that it is the water flow temperature that is being limited. When the system is operating in weather compensation mode, the user can vary the water flow temperature by changing the setting on the controller screen, it may be that this is the adjustment being limited. Probably the only way to find out would be to change the settings in a logical manner and see which adjustment is affected.

My assumptions above may be completely wrong, and the 'upper' limit is the point at which the compressor is stopped when the water flow temperature increases above the calculated value, when the weather is mild, and the 'lower' value is the temperature at which the compressor restarts in the above situation.

Can varying the Flow Temp Range Min and Max make quite a difference to the performance of auto-adapt at least to start with? Would seem like the default min temperature is a bit high.

Limiting the temperature range for the water flow temperature possibly could improve the performance when in auto adaptation mode, but would also limit the response of the heat pump in varying weather conditions. If the maximum water flow temperature is limited at say 40C, but the weather turns cold and to maintain the indoor temperature requires a water flow temperature of 50C, you will no doubt have a very unhappy wife. 🙄 


   
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 mjr
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Posted by: @derek-m

For those of you 'brave' enough to give the Auto Adaptation mode a try, I would suggest that you change the 'Room temp, control - interval' from the default 10 minutes to the maximum 60 minutes, as shown on page B27 of the attached document.

Aha! I should have realised after my autumn experiments with other controllers that the interval was key to taming the aggression and that 10 minutes is far too short to see a change in the ecodan room sensor that only reads to the nearest 0.5°c. The controller turns up the heat, sees no change in ten minutes and turns it up more. 

The experiments suggested 45 minutes was best for our home, so I set the interval to 40 mins because it only has 10 minute steps. I also set the max to slightly above design temperature, for now, just in case it tried to run away.

I can only wonder at how small a space would be needed to need 10 minute intervals. What an odd default! 

The auto adapt mode seems to do some things not present in curve mode, such as running the water pump without the heat pump for a few minutes. This allows it to get closer to the data book COP than ever before. 


   
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(@derek-m)
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@mjr

Do I take it from your comments that you are actually now operating your system in auto adaptation mode?

Whilst the displayed temperature has a 0.5C increment, the actual measurement could have much smaller increments, it is dependent upon the resolution of the analogue to digital converter being used.


   
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 mjr
(@mjr)
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Posted by: @derek-m

@mjr

Do I take it from your comments that you are actually now operating your system in auto adaptation mode?

Whilst the displayed temperature has a 0.5C increment, the actual measurement could have much smaller increments, it is dependent upon the resolution of the analogue to digital converter being used.

Yes, it's now running OK in auto-adaptation mode. As well as the interval being lengthened, I also started with the house already up to temperature from curve mode, which I hadn't always done in previous tests. I will be watching it closely the next time we return from a holiday, but that could be many months.

I will wait and see how it behaves as we return to "normal" usage in the first few weeks of next year. As well as the ecodan doing a few tricks not available to me any other way I've yet found, another part of the attraction of auto-adaptation mode is that it leaves the master controller in a mode that other people can work (target temperature displayed, rather than an abstract offset). However, Domoticz on the RPi is still changing the temperature occasionally because the master controller only allows four settings per day, so a slow increase from overnight setback is not possible without the RPi.

The displayed temperature has a 1°c increment. The controller cannot display any decimals on the main screen. In the melcloud unit settings, 0.5°c is the smallest step. Maybe the ecodan uses a smaller step internally and doesn't communicate it anywhere, but that would be a complete two fingers up to third-party controllers, which it doesn't feel like they really want to do. I would have expected 0.1°c or whatever display and control steps to be available in the app if it was possible:

image

 


   
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(@derek-m)
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@mjr

I'm pleased that you have managed to get auto adaptation to work to your requirements.

It is a pity that a ramp function has not been incorporated within the controller, since being able to increase or reduce the room temperature in a controlled manner may also improve efficiency.

The industrial controller that I use measures and displays the temperature to two decimal places, so I am surprised the Ecodan does not have a resolution of 0.1C, which would be quite easy to achieve. I do believe that some of the manufacturers provide a resolution of 0.1C.


   
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(@ajdunlop)
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I'm returning to looking at the auto adaption behaviour having been experiementing with controlling our office Ecodan in other ways over the holidays. It turns out that the daily afternoon spikes in temperature in the office are as a result of the people giving off heat rather than the ASHP taking a long time to get to temperature and overshooting as I had previously thought.

I just wanted to clarify when auto-adaption is actually active. We have a FTC6 with the main controller attached to the front of the main FTC6 unit. We have a 3rd party controller that I have wacked up to a high temperature so it is always calling for heat. We don't have any other controls.

If with this set up I set the controller to room temperature mode is this auto-adaption? Or do I need the separate temperature sensor from a few posts ago or the Ecodan Wireless thermostat to have auto-adaption?

Also @mjr how are you getting on with auto-adaption? Is it still working efficiently now that you have changed the interval? Is it working better than any of the other control methods you have tried?


   
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(@kev-m)
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@ajdunlop 

Auto adaptation will work if dip switch SW5-2 in the FTC6 is on.  You don't need a wireless remote or thermistor as long as the main controller is in the main area being heated and not in an airing cupboard or garage.


   
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(@sunandair)
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@kev-m 

I’ve not used auto adaptive. Is it true that it uses the weather compensation curve as it’s source of information and some how enhances it by reading room temperature and modifies the flow temp if it needs to, to help bring room up to target temp?

Any other information on it would be welcome. Eg does it help for a radiator system? Does it automatically select the main controller thermostat?  Does it affect COP etc? Sounds useful.


   
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(@ajdunlop)
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@kev-m I've double checked and MELCloud returns "DipSwitch5": 2 which would suggest that it is turned on.

Anyone run with this for a while and seen it adapting to be a bit more controlled in how it tries to meet room temperature?

Would be really good if someone had graphs to show this happening to give an idea of how long it takes and what it does.

I've started it on our office a few days ago and am using MELCloud to schedule a setback of the temperature at 16:30 and a few increases in temperature in the morning to get back up starting at 06:30. Daytime temp is 21C nighttime and weekend is 19.5C.

Here is a graph of what happened when is switched from WC to Room Temp (Note the actual value for energy consumption is too high as I wasn't converting from the Compressor Frequency properly at the time):

Screenshot 2023 01 10 at 09.30.39

And here is what has been happening since (Note the last who on periods now are using the correct multiplier to get the consumption value):

Screenshot 2023 01 10 at 09.32.57

Not that all my data is pulled from MELCloud and subject to its estimations and low frequency of updates.

I did adjust the day time temperature up a little yesterday.

I think our Ecodan 8.5kW is maybe oversized for the very well insulated and airtight office so I would expect some on off behaviour in milder weather but currently in the auto adapt mode it flow temps are spinning up to the mid 40Cs before dropping down for a long time before the next big spike.

I have the adaption interval set to 40mins currently. Haven't really gotten my head around whether this could be too long or too short. There probably is low thermal mass in the building due to Internal Wall Insulation and stud dividing walls but very low heat loss.


   
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