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Vaillant Arotherm Settings for New Installation

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(@bontwoody)
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Im just helping my brother in law with his new 7kW Arotherm installation. I looked at a few youtube videos and found my way around the controller but Im unsure about a couple of things and the COP of the unit for heating is currently poor at about 3 (DHW is OK at 2.5).

Firstly the current room temperature on the controller seems to bear no resemblance to the actual room temperature. (see pic). Is this an issue or just annoying?

Next the unit is set up for pure weather compensation, but i can see the option for using room temperature modulation as well, has anyone any experience of this?

The current curve is 0.85, am I right in assuming that the upper and lower limits of the WC can be set separately to the curve?

Any other tips welcome 🙂

IMG 0338

 

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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(@bontwoody)
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Topic starter  

Just to say, that we have managed to set up the unit now. 22C target indoor temperature and a heat curve of 0.6. High internal temp but the wife is a freezer and room temperature is a constant cause of marital strife.

Currently running on pure weather compensation so I would still be interested to hear from anyone who uses the room temperature compensation feature.

Heating COP appears low still, but Im not sure how much the Vaillant reporting system can be trusted after reading a few online reports.

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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(@drew-pa)
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840 kWhs
Joined: 2 years ago
Posts: 72
 

Hi there,

Would need a few more details of your BIL's install.  Radiators, UFH, number of emitters, how many zones, size of property, size of water tank, number of pumps in the system, LLH etc. 

  • How are you calculating the COP? Vaillant use a different formula from everyone else.  
  • The Vaillant reporting seems pretty accurate in my experience, well for us anyway.
  • We only use pure weather compensation, we even go as far as using the adaptive heat curve, letting the Vaillant software decide the best heat curve for the property.
  • Regarding the temp reading, ours is always bob on.  Were you sat with the sensocomfort unit in your hands or on your lap for a while, they are quite sensitive units.  We've had first hand experience of this. 
  • As for adjusting the heat curve end points, this is not possible with Vaillant as far as I am aware.

Hope this helps.  

Drew 

 


   
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(@bontwoody)
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Hi Drew. Thanks for the reply. I’ll post his installation details asap. 

The work is neatly done and all the radiators were changed as per the installers spec. 

There is no LLH or buffer but they did insist on a volumiser and are using glycol instead of water and anti freeze valves. 

Im getting the COP from the app but am aware of the quirk with the way Vaillant describes their energy figures and hence the odd COP calculation. 

I haven’t seen the adaptive curve feature but have found a formula for calculating the correct curve for the desired room temperature. I can see how this all works now, very different from the Samsung setup. 

I wondered about handling the controller and the temperature reading but that didn’t seem to be the issue. In fact it seems to have stabilised now. 

If the displayed COP is correct then that is a worry and needs some investigation. 

thanks Mark

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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(@drew-pa)
Estimable Member Member
840 kWhs
Joined: 2 years ago
Posts: 72
 

@bontwoody 

sounds like you are slowly getting there.  From the checks I have done, the COP in the app seems to be fairly accurate, others have confirmed this to.  We used to have to do the calc using the figures in the controller.  Once you have the system info it will be good to get a look at it for you. Are the radiator valves all fully open?  

Drew

 


   
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(@bontwoody)
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@drew-pa Ive attached the performance estimate Drew, that is all I have. There is no UFH.

Also attached are some images of the installation. Other than the things I've already mentioned, the only other thing I wouldnt have done was run the external pipework as far as they did. BTW its white because his wife insisted on them covering it with tape 🙂

There doesnt seem to be anything obvious as to why his COP is so low, despite the settings, the flow temperature over the last couple of days was under 40C so I would have thought he should have a COP of about 4 judging by the arotherm specs.

My sceptism about the reported COP was based around discussions on Protons for breakfast,  Energy Stats Uk and a discussion on the openenergymonitor forum. If its accurate, then its a worry.

Not all the radiator valves are fully open but several are as I was trying to balance the system a bit better and warm up some cold radiators. Annoyingly the installers dont seem to have bothered.

Mark

Performance Estimate
IMG 0342
IMG 0340
IMG 0339

 

This post was modified 4 weeks ago by bontwoody

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 HCas
(@hcas)
Trusted Member Member
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Posts: 28
 

@bontwoody Can you open all valves, and reduce flow temp further? Various units have run at low 30s or upper 20s in the past days.


   
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(@bontwoody)
Noble Member Contributor
2920 kWhs
Joined: 2 years ago
Posts: 416
Topic starter  

@hcas 

Ive opened all but the bedroom radiator valves, which they want to be cooler. Im running my Samsung at about 42C flow at the moment and still getting a COP of 3.8-4.0 so the Vaillant should really be doing a lot better than it is even at a FT of 38C.

Ive attached the COP as reported by the app and the Arotherm COP figures.

 

Arotherm COP
IMG 0351

 

This post was modified 4 weeks ago by bontwoody

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 HCas
(@hcas)
Trusted Member Member
212 kWhs
Joined: 1 month ago
Posts: 28
 

@bontwoody Comparing different units in different homes is not very straightforward...

Is the Vaillant cycling a lot?


   
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(@drew-pa)
Estimable Member Member
840 kWhs
Joined: 2 years ago
Posts: 72
 

Apologies for the delay.

How is the unit set up to operate?  Are they running it a few times a day, or running it manually?  We found ours works at its most efficient if it is running in manual mode(water and heating).  Just set the temp we want and leave it.  Might be worth a try, also try lowering the heat curve a little.  

Drew


   
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(@drew-pa)
Estimable Member Member
840 kWhs
Joined: 2 years ago
Posts: 72
 

These are our figures for the month of April.  With our settings, and specific to our property of course.  

IMG 5529

   
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(@bontwoody)
Noble Member Contributor
2920 kWhs
Joined: 2 years ago
Posts: 416
Topic starter  

@hcas Hi , I appreciate the problems with comparing different systems, but this installation is relatively simple with no buffer/LLH. The estimated SCOP from the installers is 3.65 for heating so you would expect to beat that in the shoulder heating season.

I have no way of monitoring if it is cycling, but the heat pump isnt oversized for the property so I would be very surprised it it was. Apart from a couple of issues I wouldnt have done (eg gycol), it looks like a good install so Im very surprised to see such a low COP.

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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