While I am mulling this occasional drop-in-output issue, I stumpled across this (thanks Alan), and it occurs to me that there are various sensors that could/would upset the EEV control. So if a sensor was getting occasional interference etc etc, then maybe this sort of ‘flooding liquid back to the compressor’ could happen. Maybe we are overthinking it??? anyhow, monitoring EEV pulses might help diagnose . Is the EEV being told the right thing, or is the EEV being told lies??
Have you any idea of the purpose of separate two parts evaporator shown on the schematic of Daikin refrigeration cirquit? Does Samsung use same type of heat exchanger?
Hi Ivailo,
- I’m not familiar with Daikin’s, but I believe the two parts of the evaporator allow switching on and off of the economiser (by flipping the 4-way valve). It’s likely all down to the algorithm built into your controller - depending on the current refrigerant operating conditions (mainly T,P) versus their targets, it’s not always beneficial (from a CoP viewpoint) to operate - or how hard to operate - the economiser circuit. Naturally, manufacturers don’t publicise algorithm details readily - it’s where they get their competitive advantage. I think I know when my Samsung starts its economiser circuit - it’s when the compressor pressure ratio reaches a certain value - but I’m blowed if I can figure what makes it switch it off.
- The Samsung circuit is a bit similar to the Daikin:
but as you can see, it employs a separate plate heat exchanger (PHE) to do the job, and starts the economiser (=intercooler) circuit by opening the SOV (labelled V_EB) to activate it.
Hope this doesn’t confuse you further…
Sarah
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- Conditions change over time and assumptions are not valid any more
- Something is broken
- Something is behaving differently
Please see my critique for what it is.
Choosing Octopus?
I am not criticising your decision to ask Octopus to install a heat pump.
You have received good value from them…but only after you used data to prove that the initial installation - which they claimed was designed and installed to the highest standard with that whizzy MCS union monopoly certificate - was anything but.
This is not their normal customer service. This is the customer service for somebody who has them by the neck contractually and has the data and the patience to prove it / make it clear that they’re not going anywhere.
Their normal customer service is to fob folks off.
Why are MCS and their fans such as Octopus a problem?
Regular folks are not allowed to install heat pumps. They need to apply for planning permission
first. Only MCS union monopoly people get to install under permitted development.
Regular folks are not allowed to give tax rebates / BUS grants. Only MCS union monopoly people get to access those.
The bar to becoming a union member is high (you can’t dip your toes in doing one or two installs in the first year) which prevents market access for the vast majority of heating engineers.
Add to that large companies such as Octopus being willing to lose money hand over fist on their heat pump business (though they try to lose less; which is why they’re reluctant to actually deliver the systems designed and installed to the highest standard that their MCS certificates are supposedly proof of) whilst subsidising it from profits in the electricity and gas space (something which the vast majority of heating engineers can’t do for obvious reasons) and…
…you get the situation that you complained about. Not enough installers. Not enough competition. They’re choosy. They’re reassuringly expensive. And it’s all because of the MCS union monopoly, the behaviour of their allies such as Octopus, and a government who are happy for it to continue.
There’s no sour grapes here. I’m pointing out why there aren’t enough people diving into this to make finding an installer easy.
-
The MCS union monopoly wants to make it difficult to install without being a member (legal hurdles such as Planning) and difficult to compete without being a member (commercial hurdles such as BUS). Otherwise they will cease to exist because they certainly don’t do what they claim to with respect to proving that systems are designed and installed to the highest standard.
-
Big corporates that don’t want competition so support MCS, support restricted access to Planning, support restricted access to BUS, and to top it off are prepared to lose money hand over first at the moment to build market share; and possibly also going forward such that you get a cheap heat pump that later uses loads of electricity.
Once you know their game an the rules you can totally play them - as you have - by asking for the cut price install and then using independent monitoring to make 'em fix it. And a hat tip to you for that. 
There’s your “changed conditions” then
When a manufacturer releases new firmware it’s because they’ve messed something up at the design / testing stage. Not enough time in a climate chamber evaluating all operating points. Not enough testing at high loads with low water temperatures. Something where they’ve neglected to check a part of the operating envelope that wasn’t the bare minimum needed for the EE Energy Efficiency label.
The chap sent to site who ridiculed the heat meter data says they’re either employing idiots (somebody who wasn’t trained would have said that they don’t know; whereas takes an idiot to argue with a certified measuring instrument) or they know the units are not without issues and are hoping to “run down the clock” by sending time wasters in the hope that clients get bored.
Fortunately your contract is with Octopus; not Daikin. Fortunately; you’ve already raised the defect with Octopus during the warranty period. And fortunately; Octopus have a lot more leverage (number of units purchased) than you do when negotiating with Daikin on your behalf.
Watch out for the commercial incentive for them not to try too hard; or to try encourage you to deal with Daikin directly. Not. Your. Problem. If the unit does not operate in the manner that it ought to. 
(theirs to fix if you would like it fixed)
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Guess what 
… See the red circle - Samsung actually have low pressure sensor and indeed never seen superheat problem with their heatpumps…
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Earlier in this thread we’ve seen performance dips of about 15 mins duration, but this morning I’ve seen a couple of instances where electric input increased for a few seconds/minutes at the same time that flow temp dipped. See 04.17, 08.02 and 08.05 on these 2 screen grabs.
These look like something similar to the previously discussed 15 min excursions, but maybe the HP “caught” these errors and did something rapidly to correct them?
My system is Lindfield 8kW Daikin, but please ignore the rather severe air errors during DHW which I’m trying to purge with limited success
My conclusion is that it’s a cheap and nasty pos.
It kind of works but just frustrating.
I ask it to increase the flow temperature and it is just ignored.
It changes flow temperature at will, either up or down.
Whatever I do, it’s never really stable and doing what is asked of it.
And then it’s russian roulette as to whether it will go badly wrong.
Who knows where the issue is going, will it get worse, is this it, I don’t know.
And on top of all that, not a nice company to deal with in my experience.
Just a bad customer experience here, a bit sad.
It just doesn’t work properly, it’s rubbish.
I set a fixed flow temperature of 31c and runs at it all day. Increase to 32c and it stays at 31c for more than an hour.
Increase to 33c and now it is running at 35c.
It’s pathetic.
Perspective: you have one of the highest SCOPs on heatpumpmonitor? Has it dropped significantly since the error started occuring?
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I assume you informed them about your poor experiences with their service engineer, if not the engineer directly - maybe you can get someone higher up the food chain? Random faults can often be tricky to diagnose and sometimes trickier to get the manufacturer to acknowledge and/or do something about it, assuming they can - at least you can provide them with the Oem data.
Most of the time I’ve found manufacturers pretty helpful, if you can get through to the right person, but I’ve spent many an hour/weeks diagnosing faults, writing reports and chasing suppliers about faults on customers equipment that need the input from the manufacturer/factory, only to be told point blank there is no problem/fault with their equipment…and then finally, six months, a year, even two years later you hear; ‘The factory may have identified a fault which should be addressed in the next software update’ or they’ve redesigned a component etc etc. It can be very frustrating and time consuming, but we generally get there in the end….even if it dose sometimes mean amputation!
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Hi Ben,
I will try and explain why I feel like I do.
The COP/SCOP is really good but, like many people, I feel it has become an over rated way of assessing overall success of a heat pump installation.
I would get the same performance out of any 8kW Daikin heat pump, there’s nothing special about my one. From my experience with my grossly unsuitable 9kW Daikin heat pump I have just arrived at a set up and way of operating that gets the best efficiency out of this heat pump.
But it’s not a pleasant experience on the whole.
I am sure I would get the same or better efficiency from any other heat pump of roughly the correct size and have an easier time of it.
The heat pump is too big still.
But Daikin don’t make a suitably sized heat pump for my house.
And that’s the problem, the MCS, the planning laws and a lack of pertinent information from heat pump manufacturers.
I was forced to either carry on with a gas boiler or get a Daikin heat pump from Octopus, I had no other choices at the time.
In the last two years I think we have all learnt a lot about what the actual specifications of various heat pumps are in reality. We have a lot more monitored systems now and I am sure many of us would have chosen differently if we knew at the beginning what we know now.
The best thing about OEM is that we can see exactly what is going on with our heat pumps.
The worst thing about OEM is that we can see exactly what is going on with our heat pumps.
I am embarrassed to admit it, try as I might, I can’t ignore the data.
I really thought I would go into this winter and be able to pretty much forget the heat pump.
And then it starts misbehaving.
Now I know why pretty much which is good.
But I just don’t trust it. None of it is the end of the world, it heats our house and hot water and doesn’t cost a lot.
I am sure we are all of a similar character, that is why we monitor the heat pumps, I don’t think many of us could just ignore it.
The manufacturer is of no help, it’s not their heat pump that exhibits this behaviour, it is inaccuracies in my monitoring.
All I wanted was reassurance that everything was OK and that it was not about to fail leaving us with no heating, but that wasn’t what I got from Daikin.
So, all of it gets compounded, loads of, probably, small issues that when added together result in a customer that is dissatisfied and lacking faith in the product.
It doesn’t run at the flow temperature set.
The flow temperature is usually hunting by 2c to 4c, I don’t know why, perhaps it’s at the lowest flow temperature where it can just about control itself?
I don’t trust it to follow any automation.
The room temperature control doesn’t work because they don’t tell you that their heat pump doesn’t like running at low flow temperatures.
Everything you ever read tells you that low flow temperatures are best, not true with Daikin.
I only know all of this because of OEM, without it I would be blindly trying to run it as low as possible.
And maybe that is OK?
All of the data required to see what the heat pump is doing is readily available from the unit, ESPAltherma proves this, but Daikin choose to hide it and instead give us the joke data in the MMI.
Maybe they do this to keep customers happy, the less we know the better?
@Marko_Cosic is right in what he says.
The whole heat pump experience is pot luck, where you live, if you end up with a heat pump the correct size for your home and what installer choice you have.
It’s not good enough and I hope it explains why, what seem like minor problems, all add up to total disappointment.
Really, I don’t feel that I have got the best value for my money, I could have done so much better but for the MCS and Ipswich Borough Council, I feel cheated.
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Hi Tony,
Thank you for your comments.
I deal with Octopus as my installer and I would assume that they have spoken to Daikin.
I know that the people I speak to at Octopus are not happy at how I was treated.
I haven’t heard anything from Daikin.
I am not sure if I can confirm this behaviour, see the pic below, I thought it was an unbalanced system from a DT perspective and a ‘towel/radiator combo’ that was the issue on an open loop pure weather compensation 8kW setup (I shut off the suspect). I did get a fixed power line result with a narrow DT and flow temp; however, after a DHW cycle it is back to fluctuating power resulting in fluctuating DT and LWT ie back to the same state, so it’s not the ‘towel/radiator combo’ creating a short cut.
Is it an issue, I am not sure.
I do wonder if we are chasing diminishing returns, there are so many variables and situations compared to a ‘lab’, manufacturers have to cover the masses rather than a few corner case problem installs…… bad instals make the most noise on forums, I am leaning towards – I am doing my bit to save the planet, the efficiency is great the house is warm, the sun will rise tomorrow.
Ps for what it’s worth, I think Octopus did a great job and I am happy with their care, customer service and the price, in a real-world example how long would it take to recover £5k additional install costs for going with a local installer (even if you can get one) and a potential few more points on the efficiency table?
Hi Neil,
I have no problem with Octopus, they have been brilliant.
Their installation of the heat pump is pretty much immaculate.
However, they didn’t know enough when they started this and it is very clear now that they have learnt a lot.
It was a mistake going with one manufacturer, who in reality, only offer a choice of two heat pumps.
That was never going to work well in every house, as we now know only too well.
Not that it would have made any difference, one installer insisted on a 14kW Daikin in my house despite showing him our gas usage supporting a heat loss of 4kW at sub zero temperatures. He wouldn’t move but did say we might get away with the 11kW???
I wonder how I would have got on trying to get him to replace one of those heat pumps with something more suitable? I suspect not very well.
In the end, he eventually came back to me after about 6 months, aplologised for the delay, and asked if I still wanted a survey, this was a week after my first heat pump had been installed.
I am not chasing better efficiency, I get what I get and I just run it how it works best. The reality is though, no Daikin heat pump is compatible with my house.
This brings me on to another great thing about OEM, you can see how other systems work.
And, for every ying, there’s a yang.
One terrible thing about OEM is you can see how other systems work.
There’s nothing worse than seeing what you could have had!
Yes I see the issue from time to time and have ESPAltherma set up, though reporting to Daikin might be troublesome as I’d rather not expose my usage of it to them in case of warranty issues!
Any clue which of the many stats I need to gather? I only fetch what I need for emoncms right now to keep the MQTT string short:
I think lines : 12: //{0x00,4,152,1,-1,“Expansion Valve Data Qty”},
and line 87: //{0xA0,8,151,2,-1,“Expansion valve 3 (pls)”},
After quite a significant investment in hounding the installer to make good / quite a bit more involvement in day to day operations than one might like.
There’s also potentially a longevity question mark where equipment is not operating in the intended regime.
Spot on.
Historically:
“this heat pump ought to work better at lower delivery temperatures than at higher ones; yet there appears to be no performance improvement operating at lower delivery temperatures”
“why on earth are British Gas insistent that these can only be installed with Daikin cylinders; why on on earth are these not approved for use with Heat Geek cylinders?”
Now:
“Ah. These units are built down to a price.”
They are metrologically incapable of knowing the “state” of the refrigeration cycle. Schrödinger’s heat pump. They guess at the “state” using partial information. Assume the cat is alive. Yet sometimes it is dead.
This design cannot be fixed without adding components. The consequences can only be mitigated by a better “state” guess-o-rithm.
It works “ok” for the most part. Especially on wham-bam-slam high temperature retrofit installations where the performance of any heat pump takes a hammering due to the operating temperatures.
If you’re an energy business that makes more money by selling more energy; and are prioritising lowest capital cost wham-bam-slam installations; it’s quite possibly the unit for you.
We can hypothesise that the OEM know all about the issue given BG only using Daikin cylinders / Daikin not endorsing Heat Geek cylinders / Daikin editing firmware after the fact (to improve performance or to reduce warranty claims one might ask) / Daikin rubbishing 3rd party measurement instruments that highlight the issue.
If you’re more of a connoisseur; or have a large heat lad and more of a long term interest in lifecycle cost rather than upfront cost; a different unit might be more appropriate.
This doesn’t change even the Daikin being better for the environment than a gas boiler. This doesn’t change paying the wham-bam-slam price from Octopus then actually holding them to contract being a good move. The next one (whether yours or somebody else’s) will be all the better for the information sharing.
Where I DO think you’re going wrong is blaming Daikin for being unresponsive rather than Octopus.
Daikin have no commercial reason to talk to you. Octopus have given you an MCS certificate that they are claiming is proof that the design and the installation is to the highest standard. That has legal meaning. It is not “a minimally acceptable standard” or “in line with the industry average” - it is “the highest” which in law implies there is nothing better available.
It’s an incredibly dumb thing to have promised as MCS, as you’re putting all the installers on the legal back foot, but that is exactly what they advertised at the time you made this purchased decision and entered into the contract. It’s also in big letters on the MCS website rather than buried in the small print of the Octopus Terms and Conditions; and when working with with consumers the big writing trumps the small writing in the event of a conflict between what was advertised and what was delivered.
sCOP isn’t the only figure one can argue over. Hassle. Comfort. Stability etc all count. You’ve got the evidence that the unit supplied is unable to maintain stable operation due to a cost-engineering decision in the design of the unit. You’ve also got a piece of paper that says the design and the installation is to the highest standard. Point at Octopus. Ask them to ask Daikin to fix it. Or try a third unit. Not the Cosy 6. That’s an even lower quality unit even on paper (designed down to a price / poor sCOP) even if you weren’t concerned about the lack of long term testing or long term parts availability etc.
I wouldn’t set the blame at Daikin’s feet though. They’ve sold Octopus what Octopus asked for. Octopus didn’t ask for Viessman pricing, for example, and quickly stopped selling even Samsung/Vaillant that they once used to supply?
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Hi Marko,
I agree, I only deal with Octopus.
They made two big errors.
Firstly the quality of surveyors.
Secondly limiting themselves to only one heat pump supplier who only makes two sizes of heat pump in reality.
But due to my own hard work/expense/stupidity, whatever you like to call it, I cannot complain on the grounds of inefficiency with a SCOP of 5
I don’t want anything out of it particularly, I have a heat pump that works sort of OK.
What I do want is to know it is not going to go bang tomorrow, and perhaps more importantly, I want other people to think very carefully about the choice they make.
I am angry with the MCS and my local authority for forcing me down this route even though this is what our country needs.
I’m all for not burning stuff, really strongly for this, but they forced me to accept substandard junk just because of noise that actually doesn’t exist.
Ipswich Borough Council and Suffolk police are quite happy for noise levels on the roads where I live that wouldn’t be accepted at at a racing circuit (I used to race cars so I know) but they are worried about a heat pump!
Daikin quote 62dB for every heat pump they make. how?
I am disappointed with myself and wish I had waited.
I just know have haven’t had value for money.
And if the local installers were any good they would have found a solution, sadly, it was only Octopus that made it possible.
I genuinely think you have had value for money.
If you’d waited until now…you’d still have much the same on the table. Wham-bam-slam with a Daikin or homebrew heat pump from BG / Octopus; or quite a bit more money and quite a wait for the right independent to come along.
Firstly they accidentally sold to somebody who cares. (I failed that test when I tried to buy one of their early installs by asking the question “so what model range of heat pump are you going to be installing” - red flag for customer who would hold them to account 
)
Secondly the surveyor was not up to the job and has cost them a lot of money.
Selling only one make/model isn’t disastrous IMO if it does the job they want it to. Which it does. You heat with electricity now now gas. Yay for them. (margins on leccy are much higher and more controllable/arbitrage-able etc than they are on gas)
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