Posted by: @iancalderbank

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Is there any chance you could do a fuller write up perhaps in a dedicated thread,

I second that. If you could share the process for others to learn from, that would be incredibly helpful for the skillful DIYers out there.

@cathoderay yes, has been very satisfying journey, I plan to document my journey fully at some point this year.

In terms of my progress with modbus, so far just the grundfos pump with CIM500 installed and integrated using the HA modbus integration over TCP/IP, this was quick and easy.  I have been following Glyn Hudson's work for the Samsung modbus integration and will follow a similar path, but use an Olimex esp32 and ESP Home, I have a modbus hat for a raspberry pi earmarked to monitor my solar thermal but after discovering that the olimex had poe and modbs may stick with that if, it works out.  This is not tested yet, just planned, will share once done.

I have been thorough many different iterations on the HA hosting.  Raspberry Pi 3 (too slow for me), moved to dedicated X86 host (ZFS root booting Debian running supervised) then moved to VM on x86 (KVM) , then moved to VM on LXD (both debian + supervised) and very recently moved  to Raspberry Pi 4 8GB booting from SSD [I removed frigate to move frigate to a dedicated host] and will probably stay on RPi 4 8GB platform for the foreseeable future as it is the least effort.  4GB RPI4 should also be ok.

@william1066 which pump and which modbus/ethernet module for the pump? googling CIM500 finds a grundfos ethernet module that costs 729 pounds, I'm guessing you didn't use that..? I'm looking at changing my circulating pump right now (before I get a heat pump) for one that I can PWM control from HomeAssistant, if I can monitor flow rate and head as well as control it, so much the better, as that will give me a good idea what flow rate my current pipework needs, which is a really useful data point for heat pump sizing.

Posted by: @william1066

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modbus hat for a raspberry pi...

(ZFS root booting Debian running supervised) then moved to VM on x86 (KVM) , then moved to VM on LXD (both debian + supervised) and very recently moved  to Raspberry Pi 4 8GB booting from SSD [I removed frigate to move frigate to a dedicated host] and will probably stay on RPi 4 8GB platform for the foreseeable future...

Don't y'all just love the jargon! More seriously, this is one of the big hurdles newcomers need to get over if they are to make any progress in this area. I'm all for jargon, I regularly use it and wouldn't be without it in at least two major areas of activity I am involved in, but I can't help thinking tech sometimes over does it a bit.  

Posted by: @william1066

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Glyn Hudson's work for the Samsung modbus integration

This can be seen here, and it looks very interesting. I was particularly interested to see the openenergymonitor shop hardware appears to be pricey and unreliable, and in the comments it seems others have gravitated to pretty much the same hardware that I have been drawn to. Perhaps all roads do lead to Rome!

That said, I would very much like to read an account of your experiences when you have a chance to document them. No need to reinvent the wheel if someone has done it before.  

Posted by: @iancalderbank

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@william1066 which pump and which modbus/ethernet module for the pump? googling CIM500 finds a grundfos ethernet module that costs 729 pounds, I'm guessing you didn't use that..? I'm looking at changing my circulating pump right now (before I get a heat pump) for one that I can PWM control from HomeAssistant, if I can monitor flow rate and head as well as control it, so much the better, as that will give me a good idea what flow rate my current pipework needs, which is a really useful data point for heat pump sizing.

I think that you will find that many of the ASHP's actually contain a speed controlled water pump within the unit, which varies the flow rate to control the DeltaT at the heat pump.

@cathoderay You are 100% correct, and I apologise for the concise nature of my post, did not want to get into too much detail in this thread and was trying to condense many years of HA use into a single sentence.

I do this for the personal satisfaction, but frankly the government should develop policy requiring manufacturers to implement standardised technical solutions enabling innovative companies such as homelyevergreen to easily and out the box interface with all heat pumps safely (tinkering with modbus does not seem that safe to me), allowing ordinary users to get a complete picture of their heating system as easily as possible will be extremely beneficial.

@derek-m I think I got this info from one of your other posts and will rectify this shortly, though will be a bit convoluted as I need a PWM to 0-10v converter (which I have ordered) once it arrives I will attempt to integrate this into my solution, so thank you.

I was confused by the manual mentioning a PWM controlled pump, and all of the installers "simplified" documentation for Samsung I found on the web not mentioning this.  Using this forum I was able to find the details I needed to fix this omission (but I have already installed my pump, at some expense, so don't really want to change it now)

Posted by: @william1066

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@cathoderay You are 100% correct, and I apologise for the concise nature of my post, did not want to get into too much detail in this thread and was trying to condense many years of HA use into a single sentence.

I do this for the personal satisfaction, but frankly the government should develop policy requiring manufacturers to implement standardised technical solutions enabling innovative companies such as homelyevergreen to easily and out the box interface with all heat pumps safely (tinkering with modbus does not seem that safe to me), allowing ordinary users to get a complete picture of their heating system as easily as possible will be extremely beneficial.

I think you did a remarkable job of condensing many years of experience into a single sentence, but at the same time, I am also aware that in an ideal world what we discuss on the forum should be accessible to anyone who is interested enough to visit the forum. I hope in the fullness of time my beginners guide to monitoring post will go some way towards providing a guide to setting up and using ASHO monitoring for just such interested beginners. I am pretty sure I am not alone in finding at times the jargon is an uphill struggle, so I will try to keep the thread as accessible as possible.

Your second paragraph touches on some very interesting and important points. Firstly, of course folks who want the personal satisfaction of understanding their system should be able to enjoy that satisfaction, and I would say that even if I wasn't such a person. The second much more broad point is central to the whole ASHP industry. It is far too haphazard at the moment, and you are 100% right we shouldn't have to tinker with modbus (it also doesn't feel safe to me either, one of the reasons why I am treading so carefully) to get a reasonable picture of what our system is doing. Across the population there will be the whole range of people from those who want to know everything and then some more, through to Mrs Trellis of North Wales, who will write in to ISIHAC "Dear Mr Headroom My radiators are cold. Please send another £5000 by return so I can warm them up". But the general principle of encouraging all to get as involved as they feel comfortable with can only be a good thing.    

Posted by: @derek-m

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I think that you will find that many of the ASHP's actually contain a speed controlled water pump within the unit, which varies the flow rate to control the DeltaT at the heat pump.

I get the impression this is what is supposed to happen, but looking at the Midea Operational Parameters, the flow rate seems to favour around 1.4 m^3/h, it's almost always around that value when I have a look. It doesn't seem to vary very much. If I manage to get the modbus monitoring to work, we'll get a much more detailed picture, may even be able to see what causes to change if/when it does.  

Posted by: @cathoderay

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Posted by: @derek-m

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I think that you will find that many of the ASHP's actually contain a speed controlled water pump within the unit, which varies the flow rate to control the DeltaT at the heat pump.

I get the impression this is what is supposed to happen, but looking at the Midea Operational Parameters, the flow rate seems to favour around 1.4 m^3/h, it's almost always around that value when I have a look. It doesn't seem to vary very much. If I manage to get the modbus monitoring to work, we'll get a much more detailed picture, may even be able to see what causes to change if/when it does.  

Have a look at page 80 of the manual below, since it would appear that there is a fixed speed pump option.

@iancalderbank Hi Ian I would not follow my route unless you also want to also add a PWM to 0-10v converter since I was not aware of the PWM option during install [because the simplified docs from a number of wholesalers did not mention it] and I thus did not fit a PWM capable pump (I am now much better informed on this).  If you do want to go down that  [CIM500] route then there seem to be many on ebay.  I bought mine from a someone selling 20 or so as they had been incorrectly specified in a job all installed and then removed to be replaced with the correct module.  They are £75 right now.

[edit] I will point out that my heat pump [Samsung gen6] does not have a pump in it, hence this approach, as Derek pointed out, if your heat pump has an integrated pump then it is already part of the "equation".

William

@derek-m - if I read the table on that page correctly, the default setting for S2 positions 3 and 3 is 11 ie on/on which equals variable speed Wilo (pump brand) with 9.0m head (quite punchy, more than enough to make your ears pop). The m^3/h seen in the wired controller does vary, I think I have seen it as low as around 1m^3/h, but only very rarely, most of the time it is around the 1.4 mark. I think it can vary, but isn't being varied very much.