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.

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 

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

@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

@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

@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.

@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.

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

Is the Vaillant cycling a lot?

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

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

@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.