Vaillant Arotherm Owners Thread

Sustainable Energy
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1065

1. MyVaillant app COP figures have increased

2. VRC720 SensoCOMFORT temperature reads high

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1. Since the MyVaillant app update of a couple of months ago when the user interface was changed, I have noticed that the COP figures seem to have increased significantly to the point where I don’t really trust them anymore. I would like to believe that that the figure in the screenshot of 5.83 for the first 12 days of November is accurate, but the corresponding figure for the same period last year was around 4. When I raised this matter with Vaillant I just got a reply referring me to the disclaimer which says that the figures are only estimates. Has anyone with an independent monitoring system noticed this?

2. My VRC720 SensoCOMFORT temperature reads high (about 0.5C) compared to a couple of other thermometers I have which agree to 0.1C. My daughter’s house also has a Vaillant system and the difference there is also about 0.5C. I know it is possible to introduce an offset, but I wondered (again) if anyone else has noticed the same?

1066

I wanted to compare to my readings in the app only to notice I’m not getting any COP/efficiency readings at all anymore. So maybe there is something weird going on on Vaillant’s end.

1067

I have found, since a recent app update, that I have to apply a filter to get a COP readout on the app, more specifically I have to filter out cooling. This appears to be the case even if there has been no cooling during the period.

I also use HomeAssistant and the myvaillant integration (am I allowed to say that here?) to monitor my Vaillant ant the energy/COP stats have been ‘flaky’ since the last week in October, when it is said that Vaillant did make some changes. Several have reported this and its currently an ‘issue’ but I don’t think its fully understood what the underlying problem is. Hopefully as we all share more info this can be nailed.

1068

Thank you, that solved it! The COP shown is still in line with what it was before - no unreasonable increases (roughly 5-10% above my own measurements)

Sure you’re allowed :sweat_smile:, I’m also using it but due to the issues you’re describing (API rate limiting by Vaillant most likely) it’s not that useful. Fortunately I have all measurements via ebus.

1069

Edit: turning the VR940f+Sensocomfort radio receiver unit off and on has fixed this. Took a good five minutes for the boxes to reconnect.

Hi folks,

Any ideas why my Arotherm/Sensocomfort is refusing to come out of “Eco” this morning? I’d like the house to be 19°, not 18°.

It’s almost like it’s stuck at the setback temperature; if I manually set a higher temperature, say 21°, the app shows “heating” for a few seconds then reverts to “Eco”.

I’d turned on “absent mode” for a couple of days until yesterday. I’m guessing that’s caused this problem somehow.

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1070

Your OT switch off is 15C.

The system will not restart until it the outside reaches 13.9C . There is 1C hysteresis.

1 Like
1071

Hi folks,

I’m trying to reduce the amount of cycling my heatpump does. I wonder if you guys have any advice…

My system was originally installed as part of the electrification of heat scheme back in 2021. I suspect it was a touch oversized to begin with tbh.

To make it worse the heatpump is an arotherm plus 12kw running 351.06.07.

Anyway, after the scheme ended I hooked up a pi and tweaked emon to read their heat meters and I now i have a couple of years of data to play with :slight_smile:

During the summer as part of a major renovation i replaced our suspended ground floor (+rads) with solid 200mm pir and 60mm of liquid cemfloor screed with UFH at 100mm centres. I can already see from emoncms that this is doing its job.

The radiators upstairs were untouched but placed into their own zone with a separate stat. The UFH does not have a mixer valve. Both rads and UFH are fed from a buffer tank. The system did have glycol, but since the summer its just water, theyre supposed to be putting glycol back in it. (not sure if i should persue this..). The house is a 1990s build and approximately 230 sqm.

The problem is that rads and ufh have such different demands. If only the rads are in use then the system excessively short cycles, if the rads + ufh are active then too high a flow temp is sent to the UFH.. etc. This wasn’t as noticeable before because everything was a single zone..

I would like to try it with both zones tied together, this would effectively run the rads at a lower temperature but for longer and without the cycling.. but i’m fighting the vaillant controls to do so..

For now, I’ve set the rads + ufh to the same time periods and heat curves etc. but minor offsets in the ‘stat temp readings still can still cause hours of short cycling when only the rad zone is calling for heat. The system is in expanded mode, past experience was that active mode cycled much more in spring/autumn, though I haven’t tried active since adding the UFH.

If i try to set both zones to use the main stat (a vrc 720f) it will throw an error saying it cant have the rad stat unassigned. As a hack, I created a dummy Zone 3 just to assign the rad stat somewhere that kinda worked but also had issues :slight_smile: …

Does anyone have any setup suggestions? is there anything i can do to persuade the vaillant controls to treat the two zones as a single? I can send some screenshots from emoncms etc. if it would help…

Cheers

Al.

1072

Surely the first step is to get the PCB changed in the machine to sort out firmware, but maybe you’re already fighting for this?

Seems anything else is putting a plaster on a gaping wound.

Then get a competent person to balance the system and use weather compensation.

Fyi we have a 15kw unit, which most of the time is too big (design t is -7C) so we cycle over 5C, but I’ve not seen cycles more frequent than 1h30 start spacing and most starts are further apart. It does seem the software now works well - we are running inactive so true weather compensation.

1073

hello all,

struggling with my 7kw Arotherm Plus and scop. the basic issue is as far as i can tell ive never been able to get the heating scop higher than the hot water scop, which i dont understand.

system is pretty much all copper apart from one rad thats on 15mm plastic. 28mm primaries, half rads on 28mm f+r backbone, then T’s into 22mm to remaining rads. rads fed from 15mm.
primary pro external lagging and some standard lagging to most of the other pipes.

no buffer or volumizer.

original rads in some areas as wanted to see if it could cope. all get warm, though not been balanced yet.

house heat loss calculated at 7.35kw on cibse. im running it set to active and 20.5c room setting. currently trying Havenwise in desparation.

scop so far today for heating only 2.17, yesterday 2.55.
scop for hot water 2.27.

in the summer was getting 4.9 scop for hot water peak on heat wave days.

when more mild around 3.4 for heating 4 for hot water.

1074

Which heat curve setting are you currently using?

What are the parameters of your house (age, construction, size etc), and how much input power are you using per day, at a particular average outdoor temp?

1075

Rip out the second zone, revert back to a single zone and balance the rad and UFH loop flow rates to achieve your desired room temps across the whole house, at a single flow temp. Zoning only ever causes problems, as you’re experiencing…

1076

i was on 0.4 curve but it was starting to struggle with the 0c at night. Havenwise seems to adjust it up and down as it learns.

house is 1967 3 bed extended over the garage in 2005 to 4 bed then garage changed to room this year, 125m2 aprox. cavity wall with mix of 1980’s poly beads/rockwall. aprox 300mm loft. double glazing. 4kwp solar PV. given B epc before heat pump was installed.

i dont have energy monitor but Vaillant app on detailed view says 20th November 0.8c outside, 20.4c inside, and 27.1kwh electric for the heating only.

1077

Your electrical consumption for heating, at the mentioned temps and rough heat loss, sounds about right.

I’d guess that the flow/return temp sensors inside your outdoor unit are inaccurate, causing miscalculation of the CoP. I would only worry if your consumption would be really out of whack.

1 Like
1078

if they were reading wrong wouldnt it also make the hot water scop read wrong? what im getting is with the hot water in ECO mode a definite gap between the heating and hot water scops and the wrong way round. i would have thought in the worst installs the HW scop will still be lower than the heating one?

1080

“Zoning only ever causes problems” is a sweeping statement that I disagree with, and I have decent evidence to the contrary,

2 Likes
1081

You’re correct. My statement wasn’t intended as a panacea, rather a reflection of my personal experience.

1082

Maybe if the DTs were similar. But if, for example, the problem is an offset between the temperature sensors and the DT in DHW mode is greater than is space heating, which likely it is, then the fixed offset would cause a much smaller error in the DHW case than in the space heating case

1083

Yes, and your COP in summer seems reasonable so I’m not convinced it’s down to the sensors. No harm in trying flipping them around though. Apart from a Torx T20 to remove four bolts from the casing, and perhaps a flat blade screwdriver to gently lever the connectors off the pins of the sensors, it’s a tool-free job. Just flip the circuit breaker for the outdoor unit first.

1084

If you flip the locations of the sensors wont you also have to flip the connections from the sensors to circuit board. Im not saying thats difficult just being clear.

1085

16.7kw yesterday, though I did drop my target from 20.5c to 20c as battery was running out before midnight.

My house is south facing so does get solar gain. Though yesterday there wasn’t much. I also have large windows being an Alison build which could affect the heat loss calc.

Scop 2.57.