Minimum valve opening value for individual TRV

Support for our english speaking visitors

Moderator: Co-Administratoren

rizzuh
Beiträge: 3
Registriert: 19.02.2020, 17:56

Re: Minimum valve opening value for individual TRV

Beitrag von rizzuh » 11.12.2020, 08:21

The idea is to reach the target temperature but not to heat the room more than that. With a classic system with just an ambient thermostat the boiler would turn off when the target temperature is reached, but since the radiators are very hot, they will heat the room a few degrees more.

I'm wondering if it is possible to manually set the valve opening percentage - maybe not with the AP - this way I could just use HomeAssistant or just an app running on a rPI to set the valve at 25% - 50% - 100% based on the temperature difference (target - actual).

wutr
Beiträge: 33
Registriert: 04.01.2020, 21:06
Hat sich bedankt: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von wutr » 11.12.2020, 09:46

With "smart" TRVs that's no longer relevant. If they allow sufficient flow for the room to heat up in the most efficient way, the built in temperature sensor or the associated room thermostat can decide when to close the valve and take advantage of the residual heat to reach and stay at the requested temperature. Modulating the valve opening seems inefficient to me as that assumes all boilers can modulate their heat output within a massive range, which isn't the case.

Like you I would like to be able to choose how far the valve opens. If I can determine by trial and error what percentage allows the required flow I can always use that. It might reduce battery life but so be it.

rizzuh
Beiträge: 3
Registriert: 19.02.2020, 17:56

Re: Minimum valve opening value for individual TRV

Beitrag von rizzuh » 11.12.2020, 09:59

It would actually stress the batteries far less to fully open the valve then fully close it, than changing the valve little-by-little.

From a quick look at the HomeAssistant integration it doesn't seem possible to control the valve opening manually; you can only read the setting and use that info to turn on or off the boiler.

wutr
Beiträge: 33
Registriert: 04.01.2020, 21:06
Hat sich bedankt: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von wutr » 11.12.2020, 10:06

Maybe it's possible to utilise the boost functionality to somehow achieve this, but then you need to separate the boiler from HomeMatic and trigger it using Homeassistant or similar based on the actual temperature reported by either a TRV or room thermostat. It is possible to set the valve opening per valve for the boost function. I don't know if the timer would cause issues, but re-initiating boost would work around that.

StefanD
Beiträge: 25
Registriert: 17.11.2016, 10:42
Hat sich bedankt: 2 Mal
Danksagung erhalten: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von StefanD » 11.12.2020, 14:25

I had the same problem with my Danfoss valves: They do not really open until the TRV reaches somewhere between 15 and 20%.
I solved this by inserting some small metal rings (like a M3 nut) around the pin of the valve: this prevents the pin to be closed fully and thereby shifting the range of the TRV. Where previously water started to flow at say 20%, it now starts to flow at 10%.
The real problem is that all radiator valves do nothing for the first x% of opening. It would be nice if we could specify a starting value in the Homematic configuration, saying that if a valve is opened, it's set at at least x%.
It takes some experimenting to get to the right thickness of the added rings, but it does work.
Of course, the TRV needs to be recalibrated to determine its new 0%.
Nut.jpg

wutr
Beiträge: 33
Registriert: 04.01.2020, 21:06
Hat sich bedankt: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von wutr » 11.12.2020, 15:49

Oeh I like that idea!
StefanD hat geschrieben:
11.12.2020, 14:25
Of course, the TRV needs to be recalibrated to determine its new 0%.
Does it? Depending on how far you space the TRV with washers/spacers, would it not still be able to reach down far enough to push down the pin fully? I haven't tried it yet of course but theoretically, wouldn't you want it to be calibrated to 0% in the original position so that spacing it out spoofs the calibration into thinking 0% (HomeMatic/Danfoss valve) means 10%(actual valve in pipes)? Otherwise the valve would recalibrate and if you're unlucky still manage to push down the pin fully and thus find a new actual 0% position. Again, I haven't tried it whereas you have, so instead of a criticism this is more a question!

EDIT: disregard, I didn't look at your drawing properly. As long as the hole in the spacer is smaller than the driving pin from the TRV head, your fix will work.

StefanD
Beiträge: 25
Registriert: 17.11.2016, 10:42
Hat sich bedankt: 2 Mal
Danksagung erhalten: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von StefanD » 11.12.2020, 16:18

That is indeed very important: you need to block the driver before the pin in the valve is fully pressed into the radiator valve.

krawiec
Beiträge: 14
Registriert: 05.05.2020, 11:45
System: CCU
Danksagung erhalten: 1 Mal

Re: Minimum valve opening value for individual TRV

Beitrag von krawiec » 04.01.2021, 21:48

I think the EQ3 should add the possibility to manually override the opening of each valves (all e-trvs and also fallmot-c12).
It looks like the auto adaptation to the valves is not working as expected. Adding an option to set the minimum valve opening will solve the problem. Normally we have 0% to 100%.. if the valve for example is opening from 10% than we set 9% as new "zero". And if the systems needs to open the valve by 1% then we getting 10% and radiator is working. Very simple... and probably easy to implement.

Greg

Antworten

Zurück zu „HomeMatic - english“