I have just completed a retrofit of a Vaillant AroTherm Plus 7kW and was wondering if someone could help me answer the following newbie questions…
A little background:
I live in Denmark and have done a heat loss calculation for the property of just under 5.9kw for my 182m2 house that has 16mm underfloor heating installed throughout installed at 15cm centres. The design temperature 35C with a dT5 and the outside temperature minimum design temperature -12C.
I have a 300L Heat Geek Cylinder and 35mm pipe runs to the cylinder and diverter valve with heating priority configuration.
I do not have an OpenEnergyMonitor setup yet due to budget but have considered the cheaper ebusd GitHub project.
I am sure this question has been asked before but couldn’t find anything in the search.
What are my optimal SensoComfort settings?
What is the best way to get started monitoring SCOP?
@Zarch I was just reading your blog about calculating COP and SCOP and noticed that I can only see the number of KWH use for DHW, Heating and Cooling… I have no other options at all???
In you articles you refer to a menu I cannot see? Any reason why this might be the case or how I can get all the options on the Vaillant controller? Am I missing something?
@Andre_K Thanks for the reply, I really appreciate it!
I have tried searching through the Vaillant thread but didn’t find much.
I was referring to the installer installation setting. Basically I have setup my AroTherm based on the Vaillant Schematic (Basic Design 8)…
I am just trying to get the best performance out of my system but was also a little surprised that I could see so little on the wall hung controller especially after reading @Zarch blog on how to get the COP etc… The only thing I can see on my AroTherm controller is the energy usage for heating, DHW and cooling. That is literally it!
What it’s the best way to monitor the ASHP on a limited budget?
The ebusd project looks like a good budget option but you mentioned it isn’t accurate due to the Vaillant sensors not being accurate ???
The sensocomfort indoor controller (the user one) and the heat pump controller (you could call this the installer one).
You can get different info from each one.
Attaching a sensonet to get your system on the internet also allows the system to send info back to the myVaillant app which can give performance information.
If you look at the bottom on my stats here
You can see that both Vaillant methods (working figure and myVaillant app) are pretty good ballpark figures as to how the system is performing when compared to my Open Energy Mon figures.
But both these vaillant methods are summaries.
Open Energy Monitor with a heat meter is the gold standard for real time monitoring.
ebusd is an option. But it is NOT plug and play. There is a high level technical requirement needed. Linux / MQTT etc. And even then, some of the electrical and temperature data coming off the vaillant isn’t all that great.
Like you I just started my Arotherm+ 5 kW last week.
For best COP performance if you don’t have a good idea about the curve to choose, the autoadaptive curve seams to work ( Urban Plumbers https://youtu.be/gMMyhBku6Ic?t=5m49s )
And set your max flow rate permitted, leave it run 24/7 with a little room influence maybe. The system will do the rest.
BTW, don’t hesitate to look his video, amazing source of great informations.
New on Home Assistant, I discovered the ebusd thing and now trying to make it feed the emoncms… And I must say it’s really hard to set up… I’m not an IT coder
First run of the HP in cooling mode was yesterday…
Here is the result with errors of course ( HP power output was + instead of -, corrected afterwards) and you see that the accuracy of the power consumption and output isn’t that great, by 100 W steps, and I don’t refresh a lot even I ask it each 10 sec.
Flow I still need to control the offset of the vaillant temp sensors. Still lot of fine tuning here… Real heat meter is a budget
@Zarch Thanks for the response! Okay… I have both the Vaillant AroTherm 7kw VWZ AI Controller and the SensorComfort 720F/2.
I was just surprised about how little info is shown on the VWZ AI. Is there a hidden menu for installers that I don’t know how to get to? Some sort of button combination???
I have designed and installed the whole system myself as a Basic open loop system (Schematic Design 8). Heat loss Calculation we’re done using the MCS Heat Pump Speadsheets as well as calculating mass flow rates etc… for each individual UFH loop so they are only controlled via the flow rate valves on the manifold.
It’s an UFH priority design… I have also installed the Heat Geek 300l Cylinder which has a 6m2 heating area and is currently heating my cylinder by 10 degrees within 25 minutes. (Only been running for 5 days so far)
I have calculated a heat curve to be approximately 0.25-0.3 for a room temperature of 21 degrees and a flow temperature of 35 degrees dT5.
@Ulric, Yes I have been following both Adam from Heat Geek and Urban Plumber for over a year as well as some of the Skill Builder stuff that’s been done in collaboration. You can learn an awful lot from these videos.
Currently my system is setup based on the Vaillant Basic Design 8 schematic but I have changed:
Anti-legio: Off
Cylinder charging hysteresis: 5K
Cylinder charging offset: 0K
I guess I might need to change this as it gets colder but it’s fine for now.
I also have Solar so my DHW charge runs midday and that seems to be sufficient unless the whole family goes for a shower then it needs a boost.
I would love to know how to get into the VWZ AI controller. I just noticed that the sensoComfort states that the HP Controller Module has a status of Off???
As for ebusd I am not to worried about technical aspects as I have been an I engineer for the last 26 years and have quite a serious network setup…
@Ulric Looks like you are getting somewhere… Well done! It’s a little tricky trying to set things up in mid summer… The real test will be this winter. I ran my old boiler at a flow rate of 35C last winter and it worked fine!
I do have a set of Testo Smart Clamps to ensure my flow temperatures and DT are setup correctly but was hoping I could track things like the OpenEnergyMonitor solution.
Do anyone know if the Testo clamps could be used with EmonCMS?
It will at least give me an idea how far off the Vaillant stats are hopefully!
I don’t think those clamps are accurate enough. The easiest way to see how far off your sensors are is to have the heating running but with a low load/during relatively warm time so the heat pump has to cycle. In between compressor cycles the flow pump will continue. At that point flow and return temperatures should be equal. Any offset you’re seeing there is a mistake. For me it’s around 1.2 K which is quite massive, others have less. A simple correction is to measure this offset and do a manual correction. There is somr variation as it also depends on outdoor temperature but it’s a good start.
A budget-friendly improvement of the pure ebusd monitoring would be to use your own temperature probes in conjunction with the ebus flow rate measurements. This is what I’m doing - I have a microcontroller with temperature probes sending the data to the Raspberry Pi where I host emoncms + ebusd. Potentially you could even connect some DS18B20 temperature probes directly to the RPi and run some local sensing script, however that requires you to be close to the flow/return pipes. I’m running a more expensive MAX31865 + PT1000 temperature probe setup but my DS18B20 probes on the same pipe yield almost the same results. The important part is the calibration - you need to calibrate the two probes together so they show the same temperature. A simple 2-point calibration is probably sufficient. Absolute temperature does not need to be super accurate, it’s just important both probes are matched relative to one another.
This is my ebus config folder & the /etc/default/ebusd file from my system. The config was based off of some working setup I found last year and has had some stuff modified. It’s working for me and I currently don’t have the time to migrate to some official branch. It should have everything that’s needed including flow rate, but of course YMMV.
I have been having a look through the installer settings on the AroTherm VWZ AI controller and currently have a COP of 4.5 for DHW on a Heat Geek 300l cylinder.
My flow rate is 1835 l/h according to the live monitor with a system pressure of 2 bar…
I haven’t had much time to really dig into things as I am currently rebuilding my utility as most of the pipe work was run behind our existing units.
Is there a recommended dT for DHW? Optimising the heat transfer to the cylinder? Most of the stuff I have read so far has been about heating and not so much about getting the most out of DHW?
Any tips of suggestions to what I should tweak would be much appreciated.
The higher the charging hysteresis, the higher efficiency. You can set that on your controller - maximum is 20 K. Downside is that you will have more fluctuation on how hot your hot water really is.
Set che charging mode on the VWZ to “eco”. This uses a lower compressor power for higher efficiency at the cost of longer runtime. There’s an excellent article from @Zarch, check the first posts of the Arotherm owner’s thread: Vaillant Arotherm Owners Thread
The charging offset setting is ignored and doesn’t have any effect.
Unless you have very hot weather and a very low DHW temperature, I would be skeptical of the COP you’re seeing. My Arotherm tells me similar values but more realistic is a COP of 4 at 25°C outdoor temperature and a 47°C target and a 20K charging hysteresis (that’s measured with correct temperature sensors instead of Vaillant’s).
If you have it at 0K it would charge all the time as soon as temperature drops even a little bit. For your scenario with solar your approach makes sense - charge once a day. You don’t care about COP then because the energy is free anyways. If you want to maximize COP, it is better to start from a cooler cylinder.
Never played with pressure, just keeping it between the required boundaries. It’s typically sitting at 1.5-1.7 bar. I don’t see why that would have an impact though.
