That looks like some kind of bit error. Maybe there’s still something a bit funky with the connection? Are there some sources of interference nearby (PV battery storage, inverters etc)? If they don’t go away you can just filter the values out with a template sensor.
All of the connections look tight now. PV and battery connections are in another room so that shouldn’t interfere. It looks like FlowTemp also had a similar wobble.
Something seems to cause interference on the ebus, but I don’t think it’s going to be easy to track down. Could also be something with doing ebus over Wifi, but I have no experience with that. As I said before, I think I would create template sensors for all relevant sensors and just filter them to be within a physically sensible range.
Are those glitches at the same time?
Yeah that sounds like a sensible approach. They weren’t at the same time no but close, within a few minutes of each other. I’ll monitor it and see if it happens again, and if so, will create some template sensors.
Interestingly the heat_power template sensor you provided in an earlier post shows a higher heat output vs the CurrentYieldPower sensor. I would have thought the Vaillant’s output would have been inflated rather than the other way round.
That’s because Yield in Vaillant speak is just energy extracted from the environment, heat = yield + electrical.
So would you say heat_power is more accurate?
They are just different metrics. I have no clue why Vaillant has this fixation on showing the energy extracted from the environment. Heat power is what’s actually relevant, because this is what actually goes into your house.
Looking good. You’re also plagued with a significant offset between flow&return temperature. How much is the difference when the compressor is off? This will artificially inflate COP.
There are lots of details on this in this thread: Vaillant inbuilt monitoring vs MID meters - #97 by Andre_K
The compressor was off at say 11:10am, the flow was 28.2c and the return was 27.2c so only a degree in it
I’ve just compared another 7kW on Heatpump Monitor against mine when the compressor is active too, and the difference between flow and return is 2.3c whereas mine is 3.2c.
dTs between different systems are not really comparable. But given that your compressor-on dT is 3.2K and the compressor-off dT is 1K, your true compressor-on dT is around 2.2K and heat output is overestimated by a whopping (3.2-2.2)/2.2*100 = 45 % and so is the COP you see in the Vaillant app. This is close to the error I had until I fixed the temp sensors.
Wow that’s quite something, and I may even challenge Heat Geek in the UK who my install agreement is with. They install only Vaillant and guarantee the efficiency. If they’re monitoring systems and the COP is overestimated by 45% then this would in reality affect the guarantee they’re providing. Very insightful, thank you!
Do you have any additional independent heat meter monitoring or only the built-in Vaillant stuff? If you go through the thread I linked there are lots of other examples where people have had either inflated or too-low COP values because of these temperature probes. You should insist on getting the sensors replaced and make sure to take the additional precautions I outlined in my solution post.
Only the Vaillant stuff and Heat Geek guarantee based on that alone. If I increase the return temp by 1c in emoncms, would that work? I realise it’s not ideal but it would give me a more accurate picture to compare against the Vaillant COP.
That will work approximately. Unfortunately the offset is slightly dependent on the measured temperature and outdoor conditions as well but it’s a decent enough correction.
I’ll run it with an increase of 1c to get some data even if it’s approximate and then compare the COP vs the Vaillant COP and then get in contact.
Are you also using the HP for DHW? It’s a bit tricky to directly compare Vaillant COP to the one in the app. Vaillant uses all used electricity (also for pumps between cycles + standby) as reference, whereas selecting “heating” in the heatpump app just gives the active COP, ignoring the pump energy between cycles. You can however directly compare the “heat supplied” from the app to the delivered heat during active cycles.
My temperature sensors yield 21.8 kWh heat today, while Vaillant gives me 23.2, so for me Vaillant overestimates by around 6%. This directly translates to the COP.
Yeah I do use it for DHW too. I’ve cleared the data from emoncms so I can see it running with the 1c correction. It looks more realistic so far.
For heating, between 13:00 and 14:00, emoncms reports 0.292kWh electric consumption with 1.321kWh heat output (4.52 COP). The Vaillant app reports 0.415kWh electric consumption and 2.7kWh heat generated.
You’ll have to average over at least a day or longer as Vaillant’s reporting has some time delays. For November, Vaillant gives me 1431 kWh whereas I measured 1358.6 kWh, a 5% overestimation. Note that I don’t have independent flow metering and am using Vaillant’s sensor for that in addition to my own high accuracy independent temperature probes.
Also, electrical usage in the Vaillant app is really accurate.
I’m at a loss
I’m currently getting no data back from BASV whatsoever, despite polling it. I am trying to get the Room Temperature with “sensor.ebusd_basv_z1roomtemp_tempv”
Anyway any thoughts on why I can’t get anything out of BASV, or any solutions to reset it ? I have run MQTT Explorer and I can see the GETs being sent, but that’s it. There must be about 200 sensors learned in BASV and all are showing as Unavailable.
I have gotten around this for the Outside Temperature by using “sensor.ebusd_broadcast_outsidetemp_temp2_2”