@cathoderay you connect to the midea WiFi then you tell it which network to connect to (to get to the internet) and the password. Then you disconnect and never use that WiFi again. 

After that, your midea unit will connect to your WiFi and start sending data to it's servers. When you log into the app, you will then see that information. 

Does that make sense? Or maybe I'm not explaining myself well enough

@batalto - I think I get what you are saying - there's an extra layer I wasn't aware of, the internet connection. I thought it was all 'in house' ie local wireless WLAN, not my data being sent to Midea's servers, which makes me nervous! The Midea connection in Windows also says no internet connection so that fits as well, can't do what you say it wants to do. Will review tomorrow.

@batalto - long overdue update on the Midea app: could not get an emulator to work, most are very buggy, all are bloatware, virtual wifi/bluetooth (often totally absent) etc. Installed a full version of android-x86 (android ported to run on PCs) on a bootable USB stick, and ran that, got a working android 8 running but still had network connections problems, android freezing up etc. Decided to get a cheap sim free mobile on ebay and ran the Midea app which connected to the wired controller when they were very close together (2 ft) but:

(1) the Midea app wants my wifi password. I realise this is so the wired controller can send my heat pump data to the Midea server via my wireless router, and since it is a local wifi password it is probably not much use to a hacker but giving my un-encrypted password to a Chinese company? 

(2) the app wants access to my photos and videos, and apparently won't work if I don't give it access (see reviews here). Why on earth does a heat pump app need this?

The reviews also suggest the latest version of the app, MSmartHome, may be cr*pware. 

I may be being paranoid, but both (1) and (2) above are too much for me, so have decided not to proceed. I can still collect data manually from the wired controller. I can also still connect to it without using the Midea app (the ssid appears in network connections are available, and entering the unsecure and publicly available 12345678 password achieves a connection) but can't see any data but there may be a way of getting at it somehow - probably a project for long dark winter evenings.       

@cathoderay that's fair enough, your choice in the end. As an FYI on 2, you don't need to give it those permissions. However it does need location data

Also the app isn't great, however they do actually fix issues if you message them, which is nice.

@batalto - I'm glad I gave it a try, and thanks for suggesting it. If I ever get round to finding a way of getting at the controller data directly, I'll be sure to post it here.   

At last a cold spell to test the heating and see whether it can cope - it can't. The nominally 14kW Midea ASHP is incapable of warming the house to design temps when it is 0-2 degrees outside. Room stat is set to 21 degrees in a room intended to be at 19 degrees, and heating is on for 24 hours/day. Some figures:

0700: Midea ambient 2 degrees (but I think colder, frost on garage roof in sunlight still visible. LWT 36 RWT 35, many rads cool/cold, perhaps heat pump is in a defrost cycle. Bathroom 18.0 degrees (design 22 degrees), kitchen 16.1 degrees (design 19 degrees).

0800: Midea ambient 2 degrees, LWT 46 RWT 39 (gone back to heating from defrost cycle?). Bedroom 16.5 (design 18 degrees) bathroom 18.0 (design 22 degrees) kitchen 15.8 (design 19 degrees).

Conclusion: rooms are 3-4 degrees below where they should be when it is around 0-2 degrees outside. Weather comp iffy, at 2 degrees ambient, LWT should be around 50 degrees. 

FWIW: Rad surface temps (warmest panel, middle top): Bedrooms and landing: 18, 16, 42, 24; bathroom 42; living and dining room 27 35; kitchen 36; downstairs loo 35. This is with them reasonably balanced not so long ago, and all have no air in them. The rads are just fickle, eg at the moment two of the bedrooms are just not getting any heat.

Given I have now established the heating is inadequate, the question is what do I do now? 

(1) live with it, and be a living martyr to the fact the ASHP industry is not up to the job?

(2) go after my installer? I am reluctant to do this, he designed the system in good faith, using Freedom's calculator. I am also not going ignore the fact that without his assistance, I would not even have central heating (unless I reverted to oil, which at around £1/litre these days is not an attractive option), it was only his willingness to get on with the installation that meant I got a system installed by the 31st March deadline (LAD deadline, not RHI which I can't claim, as I have LAD funding). Without the LAD grant, I would not have gone down this route (that's not meant in any way to blame the LAD grant, on the contrary, it was essential to persuade me to not use fossil fuels, but rather to say that it needed both the LAD grant and my installer to make things happen. Recall there was the fiasco of the dud LAD preferred installer before my installer stepped in to save the day, without him, it wouldn't have happened).

(3) go after Freedom Heat Pumps? After all, it was their data that meant an inadequate heat pump was installed. The trouble is, I don't have any direct contract with Freedom, they can tell me (as they have done before) to f*ck off, sorry, go through my installer. I can however name and shame them, as I am doing here.

(4) go for the nuclear, or rather dip switch option, and set my heat pump to 16kW nominal. I suspect this will almost certainly be beyond my installers current experience (he is still away on his extended holiday) and I already know Freedom won't talk to me. If I take matters into my own hands, what will be the effect on the warranty? But then again. are the warranties actually worth the hassle, given we now have reasonably stout consumer law? Perhaps repairs under warranty, when they do happen, happen not because of the warranty, but because the company knows that if they don't put things right, the courts will almost certainly find in favour of the consumer.

 My 'case' is pretty straightforward, at least on paper: I was 'sold' (quotes because the LAD grant paid for it) a heating system that would heat the house to certain design temps at certain outside temps, and the installed system can't do that, ergo it is not fit for purpose, said purpose being to heat the house as specified. In normal circumstances this would be breach of contract. The problem is there is no direct contractural relationship between the payer (you and me, ie the taxpayer) and the culpable and so ultimately responsible agent (Freedom).  

@cathoderay 

are you sure it's an ASHP capacity problem?  From what you say it can heat to a LWT of 46 C and has a RWT of 39C;that sounds reasonable(ish).  It suggests your average flow is 42.  If all your rads were 42C and the house was still cold then that would be different, but most are nowhere near that.  Is there maybe a pipework issue and/or the pump(s) aren't circulating adequately?  Can you see your flow rate?  

From what you said before, the Midea output was marginal at design temps but failing to reach design room temp by 3-4 degrees is more than marginal.  Does the Midea controller record energy consumption or output of the ASHP? 

It's hard to know what to do and as you say, your contract is most likely with your installer not the agent. Maybe you could pay someone independent to have a look?  This might stick in the throat a bit but ideal but might give you some answers.  

@kev-m - there are indeed many factors at work. I suspected a capacity problem at lower ambients because if you put the correct Midea capacity data (output) in at lower ambients, the capacity falls below the demand (see posts passim, including the data/and chart in the original post in this thread): at ambients below zero, and LWTs at or above 50 degrees, the output falls below 12kW, and my heat loss is just over 12kW at -2 ambient. What happened this morning is that after the milder weather, we have had these low actual ambients, and so I can actually see what the results are.

The other big unknown is how well the plate heat exchanger works. The problem is readings are very volatile (eg compare 0700 and 0800 LWT/RWT, so it is hard to get the average picture. The same applies to the PHE flow and returns. Nonetheless, the 0800 readings suggest the average primary temp is, as you say, around 42 degrees, and the average of the rad surface temps is around 30 degrees, so at that moment in time, heat transfer across the PHE appears poor. But what if the primary circuit is ahead of the secondary circuit, ie the ASHP has galluped ahead and got the primary circuit up to approaching where it should be, and the secondary circuit, perhaps cold from a defrost cycle, is catching up?

Room temps now (1015, 2 and a bit hours after the 0800 readings): bathroom 17.0 degrees (up 0.5 degrees from 0800, still below design temp of 19 (I said it was 18 earlier, it is actually 19), bathroom 18 degrees (no change from 0800, design temp 22 degrees), kitchen 16.0 degrees (no change from 0800, design temp 19 degrees). From the Midea controller, current ambient is 6 degrees, LWT 48, RWT 42.

I can't see the flow rate in the secondary circuit, but the circulating pump is set to max constant pressure. From the Midea controller, the primary circuit is running at  around 0.8 cubic metres/h and the capacity (output) is around 6kW - well below what it should be given the capacities by ambient/flow temp tables and the fact that at this moment in time, the system should be calling hard for heat as the rooms are below design temps. This scenario (lower than expected heat pump output) could be explained by inefficient PHE transfer: the RWT remains relatively high, so the heat pump thinks it is supplying enough heat, but it isn't.

I don't think the Midea controller itself stores any historical data, so it means only moment by moment readings done by me. The Midea app may record historical data, but I baulked at giving Midea, a Chinese company, my home wifi password. I may be being paranoid, maybe not. There are also suggestions the Midea app is far from perfect, and I am not sure it can actually produce in say spreadsheet form a set of historical data.

The bottom line is the rooms are not at design temps. If it turns out the PHE rather than capacity is the problem (or part of the problem), that is still down to Freedom, who insist(ed) that a buffer or PHE be fitted, and supply one sized by them as part of the installation kit, but as far as I know, with no instructions, hence my installer's plumber getting the flow directions wrong (which are now corrected, ie contraflow).      

@cathoderay did you do your own heat loss to compare?

@batalto - yes, in effect, I had my full room by room heat loss calcs from when I first designed installed the CH in the 1980s, and I also had the heat loss calcs from other quotes. I'm pretty sure the just over 12kW to about 12.5kW  is about as accurate an estimate as I can get without doing some very fancy measurements. It's high because the building is old and leaky, with much of the loss going through the solid stone walls, and adding insulation is not an option because (a) the building is listed and (b) it's blooming expensive!

Part of the reason for allowing myself to go down the ASHP route, in a public spirited sort of way (and yes definitel persuaded/bribed by a very generous grant), was precisely to test ASHP installations in excatly this sort of 'unsuitable' property, which is the norm round here. Somehow, if there is going to be a mass transformation to ASHPs, they have to be made capable of working in these older leaky properties, and that means running the experiments to see how they can be made to work. I am just one of those experiments...     

@cathoderay if you had the loss calcs and the right sized ASHP, my question is, why isn't it making enough heat?

@batalto - my provisional conclusions are that the problem, or part of the problem, the PHE may also be partly to blame, is the nominal 14kW Midea heat pump is inadequate for my house at lower ambients, and this was only really tested for the first time this morning by which time it had been cold overnight, ie i don't have the right sized heat pump. I think it was @derek-m who came up with a rule of thumb that an ASHP nominal output needs to be uprated by about 50% to ensure adequate outputs at lower ambients. That might be a bit more than is needed, but in any event, according to Midea's own data, their 14kW heat pump produces less than 12kW at low ambients and higher (but not excessive) LWTs. The system copes with higher ambients, but doesn't in lower ambients, which is when you most need it.

The above is based on Midea's capacity (output) data. There is the additional possible problem that the PHE isn't transferring the heat that is produced efficiently from the primary to the secondary circuit. But if the max output of the heat pump is less than the heat loss at low ambients, then even an 100% efficient PHE would not be sufficient. 

PS it's forecast to be 1 to -1 degrees overnight tonight, so tomorrow morning will be another chance to see what the system can achieve is steady cold conditions. The bottom line is the room temps, if they are below the design temps, then something in the design isn't right.