PID and prediction

Tips, tricks and frequently asked questions
p82
Posts: 18
Joined: 25 Oct 2015, 12:08

PID and prediction

Post by p82 » 25 Nov 2015, 10:43

Hi,
a couple of days ago my thermostat (j073f08) shown me the option to activate PID and I accepted.
Now I have doubts, in particular about "prediction".

In the evening I set 19° at 7:15 pm.
With hysteresis my boiler started 30 min before (6:45 pm).
With PID, it starts exactly at the time I set although actual temperature was 17,7° or 18,1°(that means it reached 19* only at 9:30 pm).

In the morning I set 19* at 7:00 am.
With PID yesterday it started at 6:30 am (actual temperature was 18,4°) while today it started exactly at 7:00 am (actual temperature 18,5°).

Please may you explain me how it works so, if needed, I can change my schedules?
Thank you.
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PID 2nd day
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PID 1.PNG
PID 1st day
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hysteresis.PNG
Hysteresis
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Last edited by p82 on 26 Nov 2015, 11:10, edited 2 times in total.

TypeC
Posts: 289
Joined: 30 Dec 2014, 21:35

Re: PID and anticipation

Post by TypeC » 25 Nov 2015, 12:19

It sounds like prediction may have somehow turned off yesterday if the two heating periods you have had since then have both had the boiler turn on at exactly the time you set. The prediction and PID algorithms are separate (although they both use the results of the learning algorithm), so turning on PID shouldn't affect the prediction.

In terms of how it works (or is supposed to work), it's fairly simple. The learning process determines the rate at which the house heats up and it should bring the heating on early enough for that rate to mean the temperature hits the set point at the time you specify, based on the temperature it is heating from (with, I think, some input from the outside temperature too). With it off, obviously, the heating just comes on at the time you specify. It's nice in principle but it didn't work for us - our bedroom was getting hot way too early and waking us up.

p82
Posts: 18
Joined: 25 Oct 2015, 12:08

Re: PID and anticipation

Post by p82 » 25 Nov 2015, 12:33

Yes, it seems that prediction is not working but I checked my settings and it's still active.

In addition, I've doubts because I had different behaviors without evident reasons:
- no prediction monday in the evening
- prediction worked yesterday morning
- no predicion yesterday in the evening
- no prediction this morning

Airmaxchen
Posts: 11
Joined: 12 Nov 2015, 09:30

Re: PID and prediction

Post by Airmaxchen » 26 Nov 2015, 11:45

I have a similar problem here.
PID is active but the prediction dosn't really work. It's turned on but it's still saying that it isn't available yet so it still uses the 30 min. preheating. But that's not enough at all.
Shouldn't the prediction be available at the same time as the PID?

Brieuc_Netatmo
Posts: 3016
Joined: 02 Jan 2014, 11:20

Re: PID and prediction

Post by Brieuc_Netatmo » 26 Nov 2015, 18:33

Hello,
Please see this post: viewtopic.php?f=20&t=5107
Brieuc - Netatmo Team

p82
Posts: 18
Joined: 25 Oct 2015, 12:08

Re: PID and prediction

Post by p82 » 27 Nov 2015, 10:53

Hi Brieuc_Netatmo, thank you for the link, I read it already before posting.
I thought that Prediction was working in my system because it's active in my settings.
Now I understand that PID is working but prediction is still "training". Correct?
There's a way to check when prediction is actually active or not?
Thank you.

Airmaxchen
Posts: 11
Joined: 12 Nov 2015, 09:30

Re: PID and prediction

Post by Airmaxchen » 27 Nov 2015, 12:51

In my case, in the advanced settings it tells me right below the switch for the prediction, that it isn't ready yet. (german version)

p82
Posts: 18
Joined: 25 Oct 2015, 12:08

Re: PID and prediction

Post by p82 » 27 Nov 2015, 15:03

In my case I see both PID and Prediction activated but prediction doesn't work at all (boiler starts exactly as per my schedule).
Attachments
Settings.PNG
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adamsutton
Posts: 2
Joined: 30 Nov 2015, 15:52

Re: PID and prediction

Post by adamsutton » 30 Nov 2015, 16:02

I had similar. Last Friday the app told me PID was now available and I selected it, this seemed to result in the thermostat continually switching the boiler on and off only keeping it on for a couple of minutes at most. This happened Saturday morning until I switched it back to hysteresis since I was concerned about the continual firing of the boiler off and on

I can confirm prediction was switched on too.
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TypeC
Posts: 289
Joined: 30 Dec 2014, 21:35

Re: PID and prediction

Post by TypeC » 30 Nov 2015, 21:22

adamsutton wrote:I [selected PID], this seemed to result in the thermostat continually switching the boiler on and off only keeping it on for a couple of minutes at most
This is what it's supposed to do (at least if the setpoint and actual temperature are close to one another), although the minimum firing time defaults to 2 minutes, so "couple of minutes at most" might actually be "couple of minutes at least" :). Frequent switching is how the temperature is maintained very close to the target temperature - essentially, enough heat is put into the house to counteract the predicted loss of heat and this is done in bursts short enough to (hopefully) avoid any noticeable temperature fluctuations.

If this concerns you, you can change the minimum firing time in the settings. I've changed mine from 2 minutes to 4 (or 5, can't remember now).

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