Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

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sinelvik
Posts: 3
Joined: 26 Nov 2022, 19:26

Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by sinelvik »

Hi,

I have connected Netatmo's OpenTherm thermostat to OpenTherm boiler, and I have three questions:

1. It controls temperature of water, but it does not look equitermic regulation is working:
The boiler works until the target temperature is reached, and then it stops working, and working again when the temperature is lower then target. (see graphic) So basically it works like ON-OFF thermostat with only difference that when the status is "ON" temperature of water depends on outdoor temperature. As I know with equitermic mode (the only reason to use OpenTherm regulators) boiler should work permanently
Image

2. Also I do not see enough parameters to configure the curve. As I know, there is needed two parameters to create correct curve: "level" and "slope". But in configurations I see only "slope" (named as heating curve). How to configure it properly? Does "heating curve" learns automatically or I need to change it manually? Default value of 2.6 seems too high for me.
Image

3. Also as you can see from the first image, predicting does not seem working. It starts heating only after raising the temp by schedule, not even 30 minutes earlier.

I will be grateful for the answers.
Fauccon
Posts: 3
Joined: 10 Dec 2022, 17:20

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by Fauccon »

Same problem here. Switched from the 'smart' thermostat to the modulating one, but the latter still seems on/off. Furthermore, like yours, there is no anticipation time at all. It switches on at the given time point. Even when 'anticipation' is switched off, there is no 30 mins (standard) pre-heating period. Seems that this is a more expensive thermostat with less functionality!
Screenshot of settings
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Fauccon
Posts: 3
Joined: 10 Dec 2022, 17:20

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by Fauccon »

@sinelvik, from your screenshot, it seems you are in hysteresis mode, not in the advanced mode. See my sceenshot, which is in advanced mode. Still, same issues remain.
In addition, I miss the meaning of "Minimal heating period", with a minimal setting of 2 mins. I thought that a modulating thermostat had no minimal heating period, but could be continuously 'on', be it at lower temp., to maintain a particular room temp.
sinelvik
Posts: 3
Joined: 26 Nov 2022, 19:26

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by sinelvik »

Fauccon wrote: 10 Dec 2022, 17:49 @sinelvik, from your screenshot, it seems you are in hysteresis mode, not in the advanced mode. See my sceenshot, which is in advanced mode. Still, same issues remain.
In addition, I miss the meaning of "Minimal heating period", with a minimal setting of 2 mins. I thought that a modulating thermostat had no minimal heating period, but could be continuously 'on', be it at lower temp., to maintain a particular room temp.
Yes, you are right modulating thermostat should be continuously 'on' but at lower temp.
Btw Advanced (PID) algorithm is even worse then Hysteresis and should not be used with modulating thermostats at all.

Honestly I think Netatmo was not thinking about modulating at all, I think I will return the thermostat.
sergeantd83
Posts: 84
Joined: 12 Nov 2020, 13:21

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by sergeantd83 »

The advanced PID algorithm probably is the “Low Load Control” feature. When the flow water temperature is higher than the Control Setpoint the thermostat asks ( This issue happens when the boiler works on 0% modulation ) then this type of regulation is triggered. It works in a higher Control Setpoint value with 0% modulation and a PID algorithm calculates the ON time per given interval. Actually this is the most modern type of regulation in modern thermostats for handling an oversized boiler.
Fauccon
Posts: 3
Joined: 10 Dec 2022, 17:20

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by Fauccon »

At https://resources.pcb.cadence.com/blog/ ... resis-work I found:
If a system demands a precisely regulated temperature, using a PID (proportional-integral-derrivative) controller is a better option. A PID controller’s algorithm is based on the proportional, integral, and derivative constants and it automatically tunes temperature regulation depending on the monitored feedback. The result is a precise temperature value that’s unachievable with temperature hysteresis control. 

BTW, I 'fixed' the anticipation by switching it off for one day (one cycle). After switching it on it anticipates nicely, depending on the outside temperature, between 30 and 60 mins at the moment.
sinelvik
Posts: 3
Joined: 26 Nov 2022, 19:26

Re: Modulating Thermostat changes the temperature, but the mode still looks like ON-OFF

Post by sinelvik »

Fauccon wrote: 14 Dec 2022, 20:33 At https://resources.pcb.cadence.com/blog/ ... resis-work I found:
If a system demands a precisely regulated temperature, using a PID (proportional-integral-derrivative) controller is a better option. A PID controller’s algorithm is based on the proportional, integral, and derivative constants and it automatically tunes temperature regulation depending on the monitored feedback. The result is a precise temperature value that’s unachievable with temperature hysteresis control. 

BTW, I 'fixed' the anticipation by switching it off for one day (one cycle). After switching it on it anticipates nicely, depending on the outside temperature, between 30 and 60 mins at the moment.
Yes, now anticipation is working for me as well. But I still miss proper heat-water temp. configuration. Heating curve "0.1" provides ~40c temp when there is around +5c outside (which is too hot), and ~45c when there is -10c (which is too low). Adding "level" parameter and building proper heating curve might resolve the issue, I do not understand why we do not have it in the app.
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