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Vaillant ecoTEC Plus with sensoCOMFORT and weather compensation

 
Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 3 weeks ago
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trebor12345
 trebor12345
(@trebor12345)
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Joined: 3 years ago
Posts: 213
Topic starter 06/10/2026 4:03 pm   [#3184]

Powering up my new Vaillant which was installed earlier this year, so just testing ahead of the season.  So I have set INACTIVE as I wanted to run full weather compensation (so NO influence of any temperature controllers).  And as a test today I set a weekly planner for the HP to run for 2hours between 2pm and 4pm.  It came on at 2pm but didn't turn off at 4pm.

So when running pure weather comp, is the weekly planner NOT active?  Screen prints of my set up attached.

(PS note.  Only trying to running a time schedule such that I can use overnight peak rates, house only needs 4/5 hours a day/night in the shoulder months, so will run 24/7 once winter is here.)

Screenshot 2026 10 06 at 16.35.21
Screenshot 2026 10 06 at 16.34.28

This topic was modified 3 weeks ago 2 times by trebor12345

2024 build bungalow, Southern England, 179 m2, 12w/m2
Underfloor heating, fully open
Vaillant aroTHERM plus 3.5kW
50 litre volumiser
3.6KW solar panels
Tesla 13.5kw Powerwall 3


   
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Batpred
 Batpred
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Posts: 1211
07/10/2026 7:53 am  

I noticed something similar. We use weather comp and the temp sensor with time periods and noticed it starting to warm before the non peak leccy period..  

Curious on what you find, since when it gets colder, I would like to have it relatively aligned to the TOU times (and our battery level).. 

image

8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kW export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; Vaillant Arotherm Pro 7kW; 100Amp head, HA lab on mini PC


   
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JamesPa
 JamesPa
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Posts: 5569
07/10/2026 8:20 am  

@batpred @trebot12345

I don't know the answer for certain as mine is on 24*7 but is it possible that, when in timed mode, 'off' is actually 'setback'. 

Some conventional electromechanical thermostat controllers work this way and it's more than possible that Vaillant does.  Worth checking the manual and/or programming explicitly a rather low target temp in the off periods to see what that does.

Also don't forget that the way the Vaillant target temp works (when room temp mode is 'inactive') is to modify the WC curve not like a thermostat, so reducing the target temp turns it down not off.

Hope that gives you some lines of experiment!


This post was modified 3 weeks ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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Batpred
 Batpred
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Posts: 1211
07/10/2026 12:21 pm  

Posted by: @jamespa
↑

Hope that gives you some lines of experiment!

Well, at the moment I am busy as we are experiencing some comms glitches - that I am trying to get Vaillant to address (beyond saying "please reboot"). 

But if this misalignment with TOU continues, there will be an early Autumnal call to the installer...


This post was modified 3 weeks ago 2 times by Batpred

8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kW export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; Vaillant Arotherm Pro 7kW; 100Amp head, HA lab on mini PC


   
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trebor12345
 trebor12345
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Posts: 213
Topic starter 07/10/2026 1:32 pm  

Posted by: @jamespa
↑

@batpred @trebot12345

I don't know the answer for certain as mine is on 24*7 but is it possible that, when in timed mode, 'off' is actually 'setback'. 

Some conventional electromechanical thermostat controllers work this way and it's more than possible that Vaillant does.  Worth checking the manual and/or programming explicitly a rather low target temp in the off periods to see what that does.

Also don't forget that the way the Vaillant target temp works (when room temp mode is 'inactive') is to modify the WC curve not like a thermostat, so reducing the target temp turns it down not off.

Hope that gives you some lines of experiment!

JamesPa Thank you for the reply.  Its all about configuration.  So now with my schedule set for overnight and have set a set-back, all working fine on the tests I ran today.

I didn't know that the set-back effectively lowers the heat curve that you have set.

 


2024 build bungalow, Southern England, 179 m2, 12w/m2
Underfloor heating, fully open
Vaillant aroTHERM plus 3.5kW
50 litre volumiser
3.6KW solar panels
Tesla 13.5kw Powerwall 3


   
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JamesPa
 JamesPa
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Joined: 4 years ago
Posts: 5569
07/10/2026 1:44 pm  

Posted by: @trebor12345
↑

 

I didn't know that the set-back effectively lowers the heat curve that you have set.

Yes, its described in the sensocomfort manual.  Its also very sensible.  Many heat pumps can only do setback by invoking on/off working, bouncing off a thermostat/temperature sensor.  Vaillant and some others have gone about it a different way which ensures that you can program a setback (or set forward) whilst ensuring the heat pump continues to operate efficiently.  Furthermore it preserves a familiar interface to setting room temperature (ie a simple dial) whilst at the same time preserving operation by WC.  Brilliant IMHO.

If you want it to bounce of a temperature sensor you can also do that, just enable extended mode!


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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