I haven’t had value for money.
I had no choice.
BG offer a choice.
I wanted a Vaillant but couldn’t get anybody to install one here.
Whether you call it value for money, I don’t know.
I paid a lot, remember I paid for a 9kW Daikin, a much higher spec heat pump than I actually have.
I have had no refund. I paid for a 9kW daikin and that is not what I have, they cost a lot more.
As far as I am concerned I had an unsuitable heat pump installed because no other installer could come up with a solution and Octopus mucked up the heat survey.
Now I have had to accept the next best alternative having paid for something unsuitable.
I have had a better service than I might have got elsewhere but nevertheless, I haven’t got what I should have got if somebody who knew what they were doing had done it.
I never put a price on it, you just expect professionals to know what they are doing.
Sadly, they know less than me, which isn’t saying much!
I could have done better with my money or just a little bit more.
I am not a happy customer and that is it.
There will be good and bad installations from both one man bands and larger/corporate companies - I guess word of mouth is often your best bet, but it’s a bit of a feeding frenzy at the moment especially with grant funding in the mix, not to mention a general lack of labour etc and would encourage people ask about previous installations and proposed system design spec.
thought i would share my system on this thread
also a octopus heat pump install which had a 9 kw Daikin installed but the survey was terrible , now we have a 6 kw heat pump installed now and is working better
please read the notes on my system to give you better insight
https://emoncms.org/app/view?name=My%20HeatPump&readkey=1da9e37af3d5ac9669792233ea85675c
have you tried to turn off the modulation ??
I’m
Using espaltherma , with a independent power meter
the system does seem to run smoother occasionally , but then after changes in the mmi is disrupts it again ,
Or unstable after a hot water cycle
OK that’s the expansion valve data included and being saved by Home Assistant. It’ll be a waiting game for the next “issue”.
Interestingly I was searching around for the string “expansion valve” and found this little nugget in another thread:
I had a visit from a Daikin engineer today.
He installed new firmware on the outside unit that is supposed to help the response time of the expansion valve.
@matt-drummer did any of your Daikin engineer visits mention this firmware?
@squarepeg77 did the engineer give any more details on what the issue was?
From memory that was a 9kW unit and as my 8kW was installed Jan 11th then I had a firmware update of the outdoor unit around march. The question is was this issue with the bigger unit also present on the smaller unit but not addressed until a later fw release / has the release we got made it worse?
Unless we have access to an engineer inside Daikin or with access to a detailed change log I doubt we would easily find out.
Hi Ali and Zak,
I remember reading that post and it is related to the larger unit. If I had known about the tape heaters and I could have turned them off it may have been enough to make me stick with the 9kW.
I was always in two minds about swapping and declined the first offer of a swap in December last year. I was reluctant to swap as I felt the bigger units were of a superior quality.
The only firmware update I have had on the 8kW made overshoot adjustable in radiators.
I do not know if anything else was updated.
My 9kW ran really well compared to this, stable and perfectly controllable, with its obvious limitations.
Hi Chris,
I don’t run with any modulation, it is pure fixed lwt, no wdc, nothing but overshoot enabled to make sure it actually runs.
So here is a good example of how bewildering I find this heat pump.
It is today. Maybe @johncantor has a better idea of what is going on but I will say what my diagnosis is.
The flow temperature is set at 32c. As it gets warmer outside something is causing the heat pump to become more and more unstable, either a direct result of the increase in outdoor temperature or something caused by my house because of the increase in outside temperature.
The flow temperature, electricity consumption and heat output are jumping about quite wildly and the efficiency is dropping even though the outside temperature is increasing.
I think that the heat pump has pretty much lost control of the flow of refrigerant and is really struggling. I always get the feeling at this stage that the flow temperature is now too low for the increased outside temperature and this is why I tend to run at higher flow temperatures when it’s warmer, not by much, but just enough to keep it more stable.
It’s relatively inefficient in the state it is now compared to when it is more stable.
This stops me running a wdc because I don’t need the lwt to be as high when it is colder outside as it needs to be when warmer.
And then I have to choose whether to have the heating on and accept too much heat or turn it off.
I can’t run a heating schedule without invoking Madoka control and I don’t want to do that because of the 2c hysteresis on the room temperature.
I have spoken to Octopus engineers about replacing the Madoka with something else and they suggest Tado but it involves running wiring to the heat pump. I have asked if Octopus can help.
And here it is about an hour later. It has now stabilised itself and the efficiency increases as we would expect.
It is pretty clear if you draw a straight line through the bright blue COP that the period of severe instability results in a significant drop in efficiency compared to stable operation.
I am seeing the same thing, I have been moving the offset to see the results, Yellow real-time COP and Blue is an average COP over 5 mins.
I know its above and beyond what is expected of a home user but we are particular and like the data, I have implemented my own Ground floor temp control with Home Assistant - you can set your own hysteresis, set and target temp, cycle etc, you can use any temp sensors IP, Zigbee, Z-Wave place them around the house to get an average, it would cost less than £50 and a bit of time to get exactly what you want. Link to my trail below if anyone is interested?
This is a long shot , I did see some strange behaviour once , after a change I made to the weather curve
. This continued for a few hours and after that I removed the mmi causing it to shutdown ( pull just at the top ) after the reboot things went back to normal , might be worth a go
Chris
I have a theory - my DT is set to 5, while messing around with the WDC the system reboots and I noticed the baseline flow of water after 6hrs of heating was 26, my WDC is set to 28 @ 10, the current outside temp is 11, so the system is targeting a LWT of 28, but it’s trying to maintain a DT of 5, so is overshooting (have set to 4) to 31 by increasing the power, then is steps back resulting in micro power bursts and a flow temp between 28 - 31, @matt-drummer I think ur DT is 8 is this too much for the logic within the SW at higher outside temps, what is your base flow temp without heating (turn of the heating and run a short air purge then measure 5 min job) does this match the LWT and DT of 8 or is it less?
I have just set my DT to 3 to see if I can get a steady power draw.
after a very short period i have some results, its not conclusive but the fluctuations are not immediate as before, worth a test @matt-drummer just tweak your DT based of an unheated baseline LWT? -
** update it did not work 
but i did update the lowest flow temp thanks @matt-drummer **
Hi Neil,
My dT is actually set at 10c because I run in the radiator setting.
I do this to keep the flow rate on the floor, it is the only way the flow rate remains anything like steady.
I can run at around 26/27 flow if I want but the heat pump is unhappy and inefficient.
I have tried dT of between 2c and 5c and none of them work as well as what I do now in terms of efficiency.
At lower dT’s I run into flow rate limitations, at a low dT the flow rate isn’t enough to get the required heat.
What I found was I needed different dT’s depending on outside temperature and it is not something I want to keep adjusting.
I also find that the flow rate varies wildly, it yo yo’s up and down, with a dT of between 3c and 5c.
I would have expected the heat pump to be able to settle on an appropriate flow rate to maintain the requested dT at a fixed lwt, but that is not what happens.
Here it is at a fixed flow temperature of 28c and a dT of 3c
I find that my current way is most efficient and easiest to control despite the shortfalls.
I only commented on it out of interest really.
understood, was your previous experience of changing the DT only with the larger unit, have you tried with the 8kW?, worth checking your baseline LWT without trickle heating, do a quick test and see the results, you could be breaking the software heating logic of the 8kW heat pump, i know the 9kW has additional heaters so most likely has a different heating logic ie behaviour?
Hi Neil,
I don’t really understand what a baseline lwt is, you just mean ambient temperature of the water in the system?
I think I understand what you are suggesting but I feel you may be missing something.
You can’t run at 28c at 11c outside and get a dT of 5c because your radiators won’t give up the heat to lower the return to 23c at the minimum flow rate.
Maybe that is why it is overshooting for you but mine is not overshooting to get to a dT of 10c.
The overshoot is there to allow the heat pump to continue to run when the return gets too close to the flow.
I am pretty sure you have nowhere near enough radiators to run at 28c flow and keep the return under control for long, that is why it overshoots. I certainly don’t have and I have 50kw of radiators…
My experience is there is no point running at less than 30c when it is 10c or more outside. It doesn’t use any less electricity, or very little less, and is inefficient. I would rather run it less and turn it on and off as necessary
I find this heat pump is most efficient when it is most stable, a wildly fluctuating flow rate just adds to the instability for me.
Hi Neil,
That is with the 8kW.
I have tried every possible combination, ufh, fan coils, radiators, dT between 2c and 5c and fixed dT of 10c with radiators. I have tried Madoka control too.
What I do now gives the best efficiency in my house.
I am not unhappy with it, again just my observations.
If I was the only person who saw this hunting in flow temperature and electricity consumption then I would know that my solution was in conflict with how it is designed to work.
But I see it on all of them and mine probably hunts the least, others certainly seem to be more pronounced more of the time.
What I am trying to do is explain and establish a link to the extreme behaviour I noticed that started this topic off.
It seems there is a refrigerant control problem and at times it can be quite severe. But also, I think there is generally a problem with refrigerant control in these heat pumps and it does affect efficiency.
There’s nothing I can do about it, but it is staring me in the face and explaining it seems useful.
And this is Zak’s dhw today.
Not a dT issue on space heating, just what I would consider to be abnormal behaviour, or maybe just normal now?
Just to add to the conversation I had my DT set to 3 earlier in the year and updated this to 5°c as the pump was running much faster and not able to maintain the DT easily and deliver enough heat (got a bit chilly when the temp dropped).
Having full radiators in theory according to Daikin we should be using DT10 but again I have tried this on my property and the outcome was not as good.
I am sure there has to be some way of taming this beast if Daikin are actually interested and it is not an “Undocumented Design Feature”.
My conclusion in terms of control is that there is too much going on.
When I invoke Madoka control with a wdc, overshoot and modulation, I end up with a heat pump that doesn’t really know what to do.
It’s trying to maintain a dT and varies the flow rate to do this at the same time as varying the flow temperature (because the outside temperature is changing and/or the room temperature is changing not enough or too much)
It’s too many variables and it just isn’t smart enough to deal with it at best efficiency because one or more things are never quite ideal.
Coupled with that, I have too much radiator capacity that takes the heat pump into areas that it can’t cope with, either flow temperatures that are too low or needing flow rates that are too high.
There isn’t one setting that works all year round. As Zak says, one day a dT of 3c is great, but then another day it won’t work as the pump can’t keep up.
And so with that, I might as well control it myself, not what I wanted, but my choice because I want it as efficient as possible, just because I can and I am too weak to resist the temptation.
