I’ve never heard of a heatpump with MID certification - that would mean a certified accuracy of measurements. You can certainly buy heatpump power meters that are. Without that, who knows? Is standby power measured? Is the glycol concentration known? Are the temperature sensors mounted well, and accurate to <0.1degC? I doubt the measurements given by an ashp are great, unless they are MID certified, as it costs more money to get accurate.
MID certification - that would mean a certified accuracy of measurements. You can certainly buy heatpump power meters that are. Without that, who knows?
You’re comments sound very defeated... Surely there has to be some usefulness out of all the information generated. When we first got data out of our replacement controller we had a COP of 1.49. We scoped and scraped and reSEATED thermistors, changed the pump speed, fine tune the deltaT and with each adjustment improved the performance. We still have the same inbuilt data gathering system but instead of a 1.49 our COP is pushing the high3s. If the baseline data is the Same then I’m happy with the progress.
After-all we are not making kryptonite, just hot water.
there’s a lot of good feedback information in these graphs
All the data apart from outdoor temp, which comes from the Met Office, ultimately comes over my local network
Doesn't the pump report its outdoor temp sensor value? It seems difficult to check weather compensating control is working correctly without that.
It does on the wired controller, and in the Midea pesky app, but we haven't located it in the midea_ac_lan messages yet, so it is not in Home Assistant. The Met Office data is from a fairly local weather station, and is probably more reliable overall, and furthermore will not be affected by the heat pump's own activities. My main reason for having outdoor temp is to see how it affects the COP.
I do plot the the Midea app ambient vs set and actual LWT on a manual basis, and also set vs actual LWT. These are based on manual transcriptions from the app/wired controller, and so are by no means perfect eg the app ambient covers the whole day (no idea how it is calculated), ditto the set LWT. The acutal LWT is a one off manual reading at around 0700 hours. I'll let the charts tell their own story:
Midea 14kW (for now...) ASHP heating both building and DHW
MID certification - that would mean a certified accuracy of measurements. You can certainly buy heatpump power meters that are. Without that, who knows?
You’re comments sound very defeated... Surely there has to be some usefulness out of all the information generated. When we first got data out of our replacement controller we had a COP of 1.49. We scoped and scraped and reSEATED thermistors, changed the pump speed, fine tune the deltaT and with each adjustment improved the performance. We still have the same inbuilt data gathering system but instead of a 1.49 our COP is pushing the high3s. If the baseline data is the Same then I’m happy with the progress.
After-all we are not making kryptonite, just hot water.
there’s a lot of good feedback information in these graphs
You are perfectly correct, if one studies Metrology, one soon discovers that 'absolute accuracy' is the 'Holy Grail'.
When specifying calibration equipment to be used in a calibration facility, to be set up onsite in a power station in Pakistan, I visited two calibration laboratories in the UK, to see what equipment was available and discuss required procedures. One of the calibration facilities that I visited was at a company called Fluke, who manufacturer very good quality test equipment. Probably one of the first things that became apparent was that repeatability was much more important than absolute accuracy. Inside their calibration facility they had three 10 volt DC units, actually manufactured by Fluke, to provide a standard 10 volts DC output, but not one of the three actually produced exactly 10 volts DC, it could be 9.9999 volts or possibly 10.0001 volts. What was more important was the fact that each unit had produce its particular output voltage consistently. They had three units, so that periodically, each could be checked against the other two, to ensure continuing stability. Probably annually, each of these three units would then be sent in turn to the National Physics Laboratory (NPL), to be compared against their eleven Fluke units.
So when it comes to a heat pump, it is extremely unlikely that any of the measurements are particularly accurate, considering the equipment used and how it may have been installed. With regard to improving efficiency, it is more important to collect data over a period of time using the same sensors, located in the same position, so that at least the measurements obtained offer reasonable repeatability, and allow efficiency improvements to be quantified with a reasonable degree of accuracy.
Historical records can be useful in identify a slow reduction in efficiency over time, which may not immediately be apparent.
I have been looking through the Python programs on Github, and I think that you may have to add some additional code to either read the ambient temperature reading from the data stream, or request that it be added to the data stream.
Edit.
I forgot to mention that I can explain if you wish.
I have been looking through the Python programs on Github, and I think that you may have to add some additional code to either read the ambient temperature reading from the data stream, or request that it be added to the data stream.
I came to the same conclusion (needs additional code) and tried some variations of the existing code, to extract to my 'testvars', but didn't get anything usable. I've also left two messages on the github pages, but no response...
I don't know what you think, but my hunch is someone is privy to either where the data is in the message strings and/or how to extract it. I find it hard to imagine they came up with the code just by chance. Or maybe they have access to something they could reverse engineer.
I do have the javascript that runs the Midea app, which does show ambient temp (and set LWT) but I couldn't see anything in the code that obviously got these values. It's possible I didn't get all the javascript, if some was hidden away somewhere. I got the javascipt by doing a backup, and then unzipped the backup files and copied the files in the Midea app folder. I can post them here in a zip file if anyone is interested in having a look.
Midea 14kW (for now...) ASHP heating both building and DHW
I have been looking through the Python programs on Github, and I think that you may have to add some additional code to either read the ambient temperature reading from the data stream, or request that it be added to the data stream.
I came to the same conclusion (needs additional code) and tried some variations of the existing code, to extract to my 'testvars', but didn't get anything usable. I've also left two messages on the github pages, but no response...
I don't know what you think, but my hunch is someone is privy to either where the data is in the message strings and/or how to extract it. I find it hard to imagine they came up with the code just by chance. Or maybe they have access to something they could reverse engineer.
I do have the javascript that runs the Midea app, which does show ambient temp (and set LWT) but I couldn't see anything in the code that obviously got these values. It's possible I didn't get all the javascript, if some was hidden away somewhere. I got the javascipt by doing a backup, and then unzipped the backup files and copied the files in the Midea app folder. I can post them here in a zip file if anyone is interested in having a look.
@sunandair You’re right, re-reading I wish I’d said it differently. Comparative measurements will be good! Caring, looking at the data is a great thing, it should help identify if things are wrong, or different. Fitting your own MID elec meter to the heatpump is very achievable, helps keep it all ‘honest’.
We have a V2G (vehicle to grid) car charger, an expensive unit, expensive to install, but free on a trial 3 years ago. It has its own internal power measurement, not MID, and no external measurements were fitted. It took me a year to figure that its measurements are wrong by over 5%, and don’t even count up standby losses. That’s probably where my frustration comes from on this topic- it could have had a £50 meter added, to a £5k-£10k (installed guestimate, free to me). I don’t understand why it’s not standard for big kit like it and heatpumps.
Fitting your own MID elec meter to the heatpump is very achievable, helps keep it all ‘honest’.
Sounds like I will have to look into this. We have a Solar wet system plumbed into the second heat exchanger of our DHW tank (you may have seen the rising tank temperature in two of the graphs I posted)
So would I need two MID meters? One for the HP and one for the immersion? It would be good to be able to isolate the savings in use of Emerson heater…
just to focus on this, we are getting 250ltres of water at 42c on a sunny January day. By March/ April we should be entirely using solar generated hot water. I’ve read from heat geek that solar thermal is 90% efficient compared to solar pv somewhere below 30%? Not sure if exact figure.
Why are we not seeing more solar thermal installations with heat pumps?
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