Unterschied Stellantriebe (Heimeier)?

[lobo]

OK.
What would you suggest as PWM "frequency" for a FBH ?
I think a 30min would be reasonable, which would mean 4 complete cycles
...
What would be the preferred regulation setup:
1) a thermal device controlled in PWM (hence: open/close)
2) a thermal device controlled by a heating actuator (hence: proportionally open/close)

Why not using something like 10-15 mins even with a Floor heating? There should be no disadvantage of it. I didn't really think long about this, but I would think you would probably reduce an overshoot with a shorter setting.

I do not see any difference in your Points 1) and 2). Basically, there are three methods:

1. Zweipunktregelung (don't know the english word...):
If the temperature is too low, the heating valve opens completely. There is a hysteresis setting to reduce the numer of switching cycles.

2. Closed loop regulation with direct switching of valve:
Here the valve (e.g. its acutator) will receive the command ON/OFF from your (Merten) RTR. So the settings for the PWM will be done in the RTR.

3. Closed loop regulation with PWM generated by acutator:
The RTR sends a 0-100% command to the actuator which will then do the Pulse Width Modulation.

Methods 2 and 3 will result in the same bahaviour of the valve, but 3 has the advantage that you can display a continuous signal in you visu. In addition, you will probably generate a litte less bus traffic (but needn't be).

I think there have been trys to increse the PWM base frequency such that the valve will be more or less standing somewhere in between open and close, but for my opinion, this is of no use...

Best regards,

Stefan

[Chris M.]

Die PWM Zeit hat meiner Meinung nach nicht unmittelbar mit der Heizungträgheit zu tun... Die Nachstellzeit (I) im PI-Regler von Deinem RTR hingegen schon. Sieh muss träger (langsamer) eingestellt werden, da sonst der I-Anteil bei einer FBH zu schnell nach oben läuft.

Die PWM Zeit hat schon was mit der Trägheit zu tun:
Die PWM Frequenz muss nämlich deutlich höher als die Eigenfrequenz des Heizkörpers und der Regelung sein.

Je weiter die Zeiten auseinander sind, um so weniger bekommt man mit, dass es sich hier um ein getaktetes System und nicht um ein kontinuierliches handelt.

[Warichet]

Why not using something like 10-15 mins even with a Floor heating? There should be no disadvantage of it.

Mmm, if we agree that the thermal actuator has a finite lifetime (as opposed to infinite), then it does make sense to minimize the number of actions of the thermal actuator. Don't you think so ?

3. Closed loop regulation with PWM generated by acutator:
The RTR sends a 0-100% command to the actuator which will then do the Pulse Width Modulation.

Ah ?!?
I had a wrong understanding of this setup.
I thought that using a heating actuator (like Theben) based on triacs would mimic the behaviour of a dimmer. That is sending a value 0-100% to the valve, hence there is no PWM involved in this setup. It is a continuous regulation, i.e. changing from a 40% open to 50% open. I thought it would be a much better system, continuously controlling a valve, than switching it On/Off as with the PWM algorythm, i.e. open for 4 min and closed for 6 min in a 10 min PWM cycle. No ? really ?

[PauleFoul]

Ah ?!?
I had a wrong understanding of this setup.
I thought that using a heating actuator (like Theben) based on triacs would mimic the behaviour of a dimmer. That is sending a value 0-100% to the valve, hence there is no PWM involved in this setup. It is a continuous regulation, i.e. changing from a 40% open to 50% open. I thought it would be a much better system, continuously controlling a valve, than switching it On/Off as with the PWM algorythm, i.e. open for 4 min and closed for 6 min in a 10 min PWM cycle. No ? really ?

This is right! The RTR is sending a value betwen 0-100% to the Heatingcontrol and that makes a ON/OFF cicle based an die PWM Time.
Example: at 40% = 4min On and 6min Off at 10min PWM-Base-Time.

In German: Nur Stellantriebe können das von Dir gewünschte/beschriebene Verhalten darstellen...

[Warichet]

Nur Stellantriebe können das von Dir gewünschte/beschriebene Verhalten darstellen...

Ah ?!?
This might be the final clue.
If I get you right:
only an EMO (motor) can open a valve at x%
a thermo device can only be open or closed, clearly, not opened at x%

Is this correct ?
If yes, than I do understand your previous remarks muuuch better

If yes, than it brings another question:
What is the benefit of a heating actuator (based on triacs) as compared to a standard switching actuator ? knowling that the "intelligence" is in the RTR ? Just a bit less clac-clac ?

[MarkusS]

Perhaps this can help a little ...

http://busch-jaeger-support.custhelp...292691&p_olh=0

[PauleFoul]

Ah ?!?
This might be the final clue.
If I get you right:
only an EMO (motor) can open a valve at x%
a thermo device can only be open or closed, clearly, not opened at x%

Is this correct ?
If yes, than I do understand your previous remarks muuuch better

If yes, than it brings another question:
What is the benefit of a heating actuator (based on triacs) as compared to a standard switching actuator ? knowling that the "intelligence" is in the RTR ? Just a bit less clac-clac ?

This is correct! See here... http://www.heimeier.com/de/PDF/Info_...02-0809-hq.pdf at Page 3 "Funktionsdiagramm"

Greatings

[lobo]

Mmm, if we agree that the thermal actuator has a finite lifetime (as opposed to infinite), then it does make sense to minimize the number of actions of the thermal actuator. Don't you think so ?

Not really - I don't know what will be the reson for a failure: the materials beeing brittle due to their age, or an increased wear due to more or less actuation. If you take a look at the construction of such an actuator, they are really robust, so even if it then doesn't last that long - you'll probably would have to change a contious drive (EMO) as well after some time; and they cost an awful lot more ...

In German: Nur Stellantriebe können das von Dir gewünschte/beschriebene Verhalten darstellen...

only an EMO (motor) can open a valve at x%
a thermo device can only be open or closed, clearly, not opened at x%

Once again, the switching behaviour is not a problem, as long as it is quicker then the control process (Regelstrecke). As stated above, the radiator will remain some temperature during a cycle and thus you would not notice inside a room if it was controlled by a contious or switching valve!

Other examples for this:
- The frequency of 80 Hz for a CRT would give a flicker-free impression onto human eyes. And LEDs are dimmed with this technique. Almost everyone (not me) sees this as a continiuos light...
- In industry, most thermal closed loop regulation will be done by a simple on/off switching. For instance I use a hotplate at work which can be controlled to +-.1°C just by this switching.
- Your switched-mode power supply in your appliances are driven by PWM (or at least by on/off switching. The capacitor at the output will result in a precise voltage

I am writing this, because I bought three of those EMOs and now when I add my existing part of the building to KNX, I will be using thermal actuators. Although I only have three of these EMOs, I already had a problem that one valve didn't close completely.

Best regards,

Stefan

[Warichet]

Perhaps this can help a little ...

Indeed, very good technical explanation.
On page 20, I read this statement...

Einige Fußbodenheizungen dürfen über Nacht nicht beliebig abgesenkt werden. Das heißt, die Absenkung des Nachtbetriebs darf einen gewissen Wert z. B. 4–6 K nicht überschreiten.

... aha! which gives a definite answer to a previous unanswered question (my previous info was: max 2°)

Weitere Informationen darüber erhalten Sie von dem betreuenden Heizungsinstallateur.

ûû, they must be kidding or the doc was written for Germany
On page 26, I read "Empfehlungen" ... very usefull

Fußboden-/Wandheizung, Elektrofußbodenheizung
Dieses System ist sehr träge, deshalb ist eine PWM-Regelung mit einer Zykluszeit von 20–30 Minuten angemessen.

... aha! which gives yet another definite answer to a previous unanswered/uncertain question

Pssst, can someone point me to an acronym dictionnary please ? I know some but not all, HKL/EI, ?

[Warichet]

@PauleFoul

See here... http://www.heimeier.com/de/PDF/Info_...02-0809-hq.pdf at Page 3

Thank you.
I didn't know they are making thermal devices as well now. I guess they got tired from the complaints about the EMO noise.

@Lobo

Not really

OK, but there are some posts in the forum, about failure of those thermal devices (and very few/none about EMO), hence this discussion makes sense.

Although I only have three of these EMOs, I already had a problem that one valve didn't close completely.

How did you notice ?

[Warichet]

As an aside .... about thermal devices.
I realize (a bit late ) that there are 2 type of those device: the NO & NC.
I got some of those devices, they are of type NC.

I do understand the difference between "Normally Open" and "Normally Closed". The question (which I should have asked earlier ) is:
when/why should one select one type or the other ?

I guess it has to do with the type of actuator used to control the device ? (opener or closer)

It looks like the NC are the most common type, as they match the classical actuator (not inverted contacts) where the actuator, when triggered, closes the contact hence energizing the thermal device, which will open the valve, allowing water to flow in the circuit.

Is this correct ?

[PauleFoul]

I think it´s the application switch between both versions. Heaters are most or ever NC. In other applications it can be better to use an NO Version.