Freedom actually said I could remove the LLH. They simply said I needed to get someone in to verify it wasn't needed and they recommended that person. So my warranty is intact
Thanks for the update, that is useful to know. Also good to note Freedom actually providing some customer service.
Midea 14kW (for now...) ASHP heating both building and DHW
@derek-m So I might be ok with what I have. It seems the heat thief has a similar temperature drop. There seemed to be benefits in not circulating glycol which is more viscous.
I am parsimonious so I heat to meet our needs or to be more precise my wife’s showers. I’ve given up using hot water for washing hands and pots and pans. I am grappling with getting it to heat on demand rather than when the sensor shows it below 38c because when she washes her hair she needs it to start near 48c (the higher temperatures just take more energy) to finish warm enough. I prefer to heat in the day or with off peak electric.
The DHW sensor is in the top inlet so we don’t heat a 210l tank completely for 2 of us. The sensor can be moved to the bottom but so far no problems in the summer for family visits.
There is a CH pump, but my niggle is that it is not controlled by the ASHP but by the zones. This means that if the DHW comes on the CH Pump continues running. Also if I use holidays the CH pump runs. This seems contrary to MCS which expects the system to be designed to run efficiently. The pump is massive and I had to set it to the lowest speed. The installer was uncertain about the use of microbore, but in fact the radiator he added with 15mm is no hotter than others. The microbore was well designed 34 years ago with masses of 22mm pipework to numerous manifolds spread over three zones.
Phil
Sorry, I was being facetious when I said 'Lucky you'.
From what I can gather, your system design and the way you are operating the system would appear to be far from ideal.
From what I can gather, your system design and the way you are operating the system would appear to be far from ideal.
I think you have very little information to warrant making such statements. There seem to be monitoring problems with systems such as EcoDan and possibly Midea. The bottom line for mine is 1850kWh for DHW and CH in the first 9 months. Other people seem to have horrendous bills. I would settle for 4,000 on a gas equivalent cost basis over a mild winter such as 2021/22. We have of course been particularly economical this winter not because we are short of cash but to do our bit during the crisis. I am weighing up what I do as I think it is important that MCS do more to ensure work they allow installers to almost self certify is satisfactory. Solar seems to be much better regulated by MCS.
I do now know the Midea has flow rate control to maintain Delta T. As you say in other threads LWT does interact with emitters. My installer can hide behind an LWT of 50c in his paperwork. To be quite frank we would be living in a sauna. I only needed 42c to cope with -9c. I think lowest LWT may not be most economical solution. It’s a case of my house, my system, my family.
From what I can gather, your system design and the way you are operating the system would appear to be far from ideal.
I think you have very little information to warrant making such statements. There seem to be monitoring problems with systems such as EcoDan and possibly Midea. The bottom line for mine is 1850kWh for DHW and CH in the first 9 months. Other people seem to have horrendous bills. I would settle for 4,000 on a gas equivalent cost basis over a mild winter such as 2021/22. We have of course been particularly economical this winter not because we are short of cash but to do our bit during the crisis. I am weighing up what I do as I think it is important that MCS do more to ensure work they allow installers to almost self certify is satisfactory. Solar seems to be much better regulated by MCS.
I do now know the Midea has flow rate control to maintain Delta T. As you say in other threads LWT does interact with emitters. My installer can hide behind an LWT of 50c in his paperwork. To be quite frank we would be living in a sauna. I only needed 42c to cope with -9c. I think lowest LWT may not be most economical solution. It’s a case of my house, my system, my family.
Phil
You are perfectly correct, it is your house, your system and your family. Please do whatever you feel is best and by all means ignore what I have said.
Hear hear, and, in fact, I think you are both right. All @derek-m is doing is pointing out you may not be running your system optimally (and for what it's worth, I suspect he is right, and in fact you all but say as much yourself, eg the CH pump behaviour), and surely a key raison d'etre for forums such as this one is precisely such discussion, but at the same time, 'my house, my system, my family' trumps all. At the end of the day, all @derek-m is doing is offering, of his own free time and good will, informed observation and advice, not damning reports and diktats.
On a more technical note: the Midea units, or at least my unit, does not appear to use flow rate much if at all to control heat transfer and/or delta t. The reported rate on the wired controller is almost always (but not always) 1.4 something m^3/h. This is a bit of a mystery to me. I can see how the compressor output sets the LWT (higher compressor output = higher LWT) but surely the rate of heat loss from the rads, and so RWT, is dependent, among other things including rad/room delta t, on flow rate, as the longer the water is in the rad, the more heat it losses. Perhaps the 1.4 something flow rate is a sort of Midea magic middle compromise worked out by the controller. Alternatively, the reported figure may not be an exact reflection of actual flow rate. The reported LWT/RWT delta t is however usually not that far out, mostly at or about 5 degrees, so the result, however it is being achieved, appears to be roughly where it should be.
Midea 14kW (for now...) ASHP heating both building and DHW
Hear hear, and, in fact, I think you are both right. All @derek-m is doing is pointing out you may not be running your system optimally (and for what it's worth, I suspect he is right, and in fact you all but say as much yourself, eg the CH pump behaviour), and surely a key raison d'etre for forums such as this one is precisely such discussion, but at the same time, 'my house, my system, my family' trumps all. At the end of the day, all @derek-m is doing is offering, of his own free time and good will, informed observation and advice, not damning reports and diktats.
On a more technical note: the Midea units, or at least my unit, does not appear to use flow rate much if at all to control heat transfer and/or delta t. The reported rate on the wired controller is almost always (but not always) 1.4 something m^3/h. This is a bit of a mystery to me. I can see how the compressor output sets the LWT (higher compressor output = higher LWT) but surely the rate of heat loss from the rads, and so RWT, is dependent, among other things including rad/room delta t, on flow rate, as the longer the water is in the rad, the more heat it losses. Perhaps the 1.4 something flow rate is a sort of Midea magic middle compromise worked out by the controller. Alternatively, the reported figure may not be an exact reflection of actual flow rate. The reported LWT/RWT delta t is however usually not that far out, mostly at or about 5 degrees, so the result, however it is being achieved, appears to be roughly where it should be.
I suspect that most heating systems, whatever the fuel source, will not be configured or operated in the most efficient manner, so one more will make little difference.
On a more technical note: the Midea units, or at least my unit, does not appear to use flow rate much if at all to control heat transfer and/or delta t. The reported rate on the wired controller is almost always (but not always) 1.4 something m^3/h. This is a bit of a mystery to me. I can see how the compressor output sets the LWT (higher compressor output = higher LWT) but surely the rate of heat loss from the rads, and so RWT, is dependent, among other things including rad/room delta t, on flow rate, as the longer the water is in the rad, the more heat it losses. Perhaps the 1.4 something flow rate is a sort of Midea magic middle compromise worked out by the controller. Alternatively, the reported figure may not be an exact reflection of actual flow rate. The reported LWT/RWT delta t is however usually not that far out, mostly at or about 5 degrees, so the result, however it is being achieved, appears to be roughly where it should be.
I got all zones running this morning and looked at output/input power (estimate from the SolarEdge App allowing for house base load), flow rate, flow/return temperatures and compressor frequency. The most evident fact is that the COP is at the benchmark figure of 4.7 with a flow temperature of 39c and 4.3 at 42c (I need to check the 42c benchmark COP). What I observed by standing by the panel was that as the LWT rises the Delta T converges on 5C, the output power reduces maintaining the COP and the compressor frequency drops. So the unit is doing its best to modulate.
With just the upstairs running the output power was observed to go as low as 4kWh, but I need to estimate the COP. With all zones the the output power stabilised at 6.7kW and was as high as 11.5kW (12kW unit) when heating up.
I found that in some rooms the rads seem to be too small because those rooms were slow to warm up. I can use the TVRs to limit the heating of the other rooms but that doesn’t, of course, make the slow room heat up quicker. So I feel inclined to ask the installer to put a bigger radiator in the dining room (triple rather than double), bigger triples in kitchen and family bathroom. I still need to check other rooms.
The issue of the plate heat exchanger/buffer is the 5C drop between its maximum radiator temperature and water leaving the ASHP. The rads have about 3c temperature variations (bottom middle is cooler).
I also need to make sure it doesn’t invalidate the 10 year warranty on the heat pump. The other aspect of this is that the 5C loss drags the COP down.
Finally, how low should the output power be able to go before the heat pump decides to take a break? The lowest I’ve seen is 4kW with one zone. I did notice that at a higher output temperature it can run longer. On days like today I have to expect that the zone thermostats will limit how long it runs.
I hope this helps convey how my system is working. It’s been off 4 hours with 1/2-1C drop.
I have been having a closer look at the midea_ac_lan software, to see how it may be possible to make additions to capture the missing heat pump data. I cannot follow the software through its normal route, since I don't know the starting point, so I thought that working backwards would be the best option.
Below is a copy of midea_ac_lan/custom_components/midea_ac_lan/midea/devices/c3/device.py, which as far as I am aware specifies most of the devices and most of the signals that can be obtained from the heat pump controller.
I have started adding comments in red to try to specify the task that each line of code is performing. Please have a look and let me know if this is of use, and correct any assumptions that I may have got wrong.
@derek-m - yes, this is similar to what I have been doing, but always better to have two brains working on this sort of problem. I've added a few more comments in blue. Note that the midea_ac_lan can also set parameters, and quite a lot of the code in that file is about doing that.
The bit I am grappling with is this: the wasilukm version of the code adds getting the 04/04 data so there must be something in the added code that does that. Github has a page (<=link) showing the additions all on one page. I can see the setting up of the parameters, and how they are processed once received, but what is it that gets them? Is a request sent, or does the code eavesdrop on a message that is sent anyway, eg by the wired controller? I can't see anything in the code that sends a request or eavesdrops on existing data. Maybe the latter is more likely: the data is there anyway, and somehow this code makes use of it?
Midea 14kW (for now...) ASHP heating both building and DHW
I think I may have discovered - totally by accident - what corrupted the Home Assistant database. The corruption happened at 2023-02-11 04:12:00.459. Buried in yet another obscure HA page (<= link) I found this:
auto_purge boolean (optional, default: true) Automatically purge the database every night at 04:12 local time. Purging keeps the database from growing indefinitely, which takes up disk space and can make Home Assistant slow. If you disable auto_purge it is recommended that you create an automation to call the recorder.purge periodically.
If that is not a smoking gun, I don't know what is.
Midea 14kW (for now...) ASHP heating both building and DHW
@derek-m - yes, this is similar to what I have been doing, but always better to have two brains working on this sort of problem. I've added a few more comments in blue. Note that the midea_ac_lan can also set parameters, and quite a lot of the code in that file is about doing that.
The bit I am grappling with is this: the wasilukm version of the code adds getting the 04/04 data so there must be something in the added code that does that. Github has a page (<=link) showing the additions all on one page. I can see the setting up of the parameters, and how they are processed once received, but what is it that gets them? Is a request sent, or does the code eavesdrop on a message that is sent anyway, eg by the wired controller? I can't see anything in the code that sends a request or eavesdrops on existing data. Maybe the latter is more likely: the data is there anyway, and somehow this code makes use of it?
You are correct. It is not just a matter of adding code in the C3 Devices routine, code also needs to be added in other routines, which is why I was working backwards to identify which routines.
A further problem is that we are not looking at exactly the same software, since your version has the added code from wasilukm. How can I obtain a copy of your version?
Since I don't have any of the software loaded on any of my PC's, I can only pass information in Word files. Is that okay.
I'm afraid that the original code is not written in a particularly structured manner, in that making additions involves updating quite a number of routines, rather than just one or two obvious ones. It is also not particularly well documented.
There are several ways we can move forward.
You can carryout modifications and send a copy for me to check.
I can add highlighted code to my present copy for you to update your version and test.
I think that it is pointless for us both to be identifying the software changes at the same time, since we may be duplicating effort. So how would you like to proceed?
Looks like you have solved your HA database problem, which again should have been better documented.
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