Just joined today and I have the same issue on my 7kw . My heat loss is definitely over 7 at -3 so it’s the first winter. Don’t shoot me down but I did install the system myself and used a 2nd hand pump. Works well on HW with my mixergy cylinder. On heating was having issues do paid for valiant come out service and they replaced the diverter and charged from 700g to a full re gas . I think 900 ISH. Anyway pump is a late 2021 model. All good but it’s a bit of an angry fridge when doing hot water or it’s 0 Deg. My heat curve is 0.75 do it works hard and as I say heat loss is over 7kw @ -3. I obviously investigated as an engineer ( not fgas) so panels off . Definitely imbalance in compressor at certain rpms . I have no warranty so this is not a let’s get it fixed gripe, it’s what it is. I say noise is tolerable, but I know if it’s cold outside. My system is outside a kitchen with 35mm primary on Tesla flex. Hoses so minimum transfer of vibration, but I notice it. No ya gonna shoot me down but I feel this push efficiency is resulting in small pumps being used, I follow the urban plumber and like his thoughts, but and here it is yes you get cycling that kills efficiently but in say - temps to say 5 ISH then s bigger pump would be better. Ok warm it cycling but the warm temperatures mean low running cost so what’s the issue , a trade off of efficiency when cost is low ? . I wanted arotherm as it’s quiet for the noise levels. Also it sorted of over performs for 7kw. I think we should put not silly large pumps in but bigger, just a bit and hope the manufacturers give better options.
Hello @ukpaisley and welcome!
I think that’s where a lot of us have got to now with Vaillants and a large part of the reason for the initial misunderstanding about output capacity was believing that the max output tables in the Vaillant datasheet were correct and included defrosts. The 7 was said to be able to output 8.6 kW on the datasheet which should have been fine for a 7 kW real world heat loss but we’ve found based on the monitoring here it to be safer to not assume that more than 6.7 kW can be sustained for long periods during heavy defrost conditions.
If I assume I will install 30kwh of batteries, then on the days with low to medium electricity requirements I will be paying about 9p per kwh including charging/discharge loses, but my marginal cost of electricity on the coldest days will be about 27p per kwh.
(But impossible to model problem of losing 15p for each kwh from PV that I fail to export.)
So saving a kwh on a very cold days is worth the same as saving 3kwh on a normal winter day. Efficiency loses due to cycling on normal winter days may be a price worth paying for a higher complete heating efficiency on the coldest days.
But the 10kw Vaillant seem to cost a few £k more then 7kw, and that pays for significant 1cop additional heat on a few days a year.
It seems that y’all are talking exclusively about the AroTHERM Plus (*/6), not the Split (*/5)?
No such problem with the Split AFAICT, at least not in BE/NL. (There’s a lively Vaillant HP owners thread on gathering.tweakers.net.)
Splits are not practical in the UK due to f-gas regulations and unwillingness of UK domestic plumbers to pay for the f-gas cert. (Our f-gas people don’t know about radators/ufh)
Splits also cost significantly more the monoblocks in UK.
hi Trystan ,
I know the vaillant have been the main topic on this, but do you know of any similar issues with Mitsubishis ecodans?
Especially the 11.2?
Has anyone got an update from Vaillant on the noise issue from the 7 kW aroTherm?
Hi Szymon, any update from Vaillant? I have the same compressor buzzing noise problem on my 7kW unit when it’s cold enough for regular defrost cycles.
No, nothing.
I have a 7kW arotherm - see previous posts for my experiences of compressor noise. I had a visit from a second Vaillant engineer after the noise suppressing tape that the first engineer fitted hadn’t fully fixed the noise problems. This second visit came after a discussion on the technical helpline where they didn’t think the noise I recorded on the video was normal.
The engineer made a fairly thorough investigation and did not find anything wrong with the mounting of the compressor or the rest of the unit. We ran the compressor at full speed and it had the same buzzing/rattling noise, but he said that from his experience that was normal for this unit and didn’t think it was a fault in the compressor. We discussed that there are some things that the installer can do to reduce the transmission into the house. I do have the impression that it is noisier when it is colder and going through defrost cycles, but the conditions didn’t allow us to test this. There are definitely certain frequencies where I get resonance and although this is clearly driven by the compressor (I see the audio frequency exactly match the compressor speed), it could well be that it is finding the resonant frequency of some of the pipework and this could be addressed.
Overall, the engineer took the problem seriously and we left it that I would speak to the installer about noise damping in the pipework, but also he said that if this did not resolve the problem, he had agreed with the senior engineer that he would come and have a look and would authorise a replacement compressor if necessary.
One comment that he made was that the 7kW units have scroll compressors (but 5kW units have rotary compressors) and the noise was consistent with this. I was a bit confused by this as I had read that scroll compressors were generally less noisy. When I looked at the specs it says that 5kW and 7kW have rotary compressors and 10kW and 12kW have scroll compressors, so I think there was some confusion here.
I will definitely be interested to hear if anyone else gets more information on this.
I’m inclined to think that “a thorough inspection” should include measuring the noise with a calibrated microphone. Then we would know whether this noise level is within quoted specification… and also within planning law.
It’s not really enough to tell the customer “yeah, they all do that”
I should have mentioned, he did measure noise levels and they were within the specified range on this occasion. I think there are a couple of things that aren’t fully resolved in my mind. First is that it definitely seems worse at subzero temperatures and the nature of the noise still seems a bit concerning to me and the fact that it is normal for the 7kW unit may still mean that the 7kW compressors generally have a problem.
They are selling the same aroTherm 7kW in Slovakia where sub zero is the norm.
I am really struggling with the noise
How did he specify the range? Vaillant only publishes a mean sound level of 54db for a 7kW unit. I do not think they ever published maximum sound levels.
The problem for me is not the noise, it’s the vibrations. I think some units are vibrating more but are not more noisy so the technicians just say they are within tolerance
When you put pressure on the case, you can hear the vibrations changing
He measured it as below 54dB and I could tell it was not that loud at 120rps with the covers on, on this occasion. I agree with Jack that vibration transferred through the unit rather than directly through the air is probably the biggest problem. So this being the case, I am hopeful that I can make some improvements by limiting the transfer through pipes and/or identifying and changing the resonant frequency of some key components - maybe the connecting pipes or another part of the unit. One thing that I now observe is I have quite severe resonance around 65-90 rps/Hz and this changed after the initial tape treatment.
If you have not already done so, I would try having a section of plasic pipe (of some sort) connecting the heatpump.
Anither option that may work is wapping the pipe in cling film, then building a heavy box round it that you fill with expanding foam.
So you now have increased resonance at ~65-90Hz, which got worse after the tape was applied?
What I can say for certain is that at speeds above this are quieter. There is a strong resonance in this range and my perception is that is louder than before the tape was applied, but I don’t have precise measurements. The striking thing is that it is now louder at these medium speeds than it is at the higher speeds.
Gotcha! So the tape seems to have improved things somewhat…