PhilT

That is odd. My FTC and MELcloud data are totally in sync and the estimated COP figures look reasonable. I know they were having some server problems recently (now fixed). Have you spoken to Mitsubishi tech? They have been quite helpful. I must admit I use MELcloud a lot and I find it really good.

What's the issue with the MELcloud app?

which tariff/rates do you have?

Mine does that quite well on "Auto" mode (a combination of WC and LC) if it is cold enough outside for modulation not to fall below minimum continuous power delivery. But if outside temp is mild it will not allow the flow temp to fall below a level corresponding to minimum continuous power delivery to prevent the compressor switching on and off, so it overshoots target temp by one degree then switches off until room temp cools to target temp again, for the reason previously mentioned.

Mine cycles between the set temp and one degree above which is fine for me. The manufacturer has confirmed that's the way it's designed to operate otherwise it would keep switching on and off around the set temp. I have radiators

I had been giving a battery some serious consideration and, running the numbers, looked feasible until Cosy came along late in Dec'22. Projecting forward from the first two weeks actual usage and costs, assuming Octopus keep the same differences vs standard variable, Cosy will save me a minimum of £300 and possibly as much as £500pa at current rates for no up front investment. It's completely changed the financial equation and now I can't get anything like the level of further incremental savings required to justify a battery. Has anyone else run the numbers and reached the same conclusion? I use around 6k kWh pa and my heat pump feeds radiators, so possibly the savings from Cosy could be greater with UFH.

I've been on Cosy since it started and my average electricity rate is working out c. 13% lower, equivalent to £300pa. I have radiators with my heat pump so can automate a tolerable daily heating/cooling pattern to fit the cheap rate periods. A battery may offer some interesting further potential given there are two three-hour mains charge opportunities at the lower rate, spread a good few hours apart.

"high-fidelity (Hi-Fi) speaker powered by electricity"🤣 Very interesting review. As a sound engineer I'm fascinated, and slightly amused, but on a serious note we do need this kind of innovation.

This one was recorded just now when the compressor was working flat out to get the DHW heating flow up to 55degC as quickly as possible in "Normal" (i.e. not Eco) mode. Sorry to rub salt into the wound - the noise you can hear in the background is the rain! I hope you get yours fixed ok. heat-pump-dhw-cycle-start.MP3

This is taken at 1 metre away but at this temp (9degC) It's virtually inaudible - the sound is swamped by the gusts of wind on the microphone ZOOM0001.MP3

I have an R32 11.2kW and the compressor noise is very much quieter than that, totally unobtrusive. The fan speeding up at low temps overwhelms the compressor noise. How old is your Ecodan?

Does this shed any light? I think this says not exactly either but both within a tight range down to -7. Ecodan R32 11.2kW nominal. Flow 45degC temp output COP input output output input input % of nom. % of max. % of nom. % of max. Min capacity -10 5.7 2.25 2.53 56% 56% 56% 56% -7 3.4 2.3 1.48 30% 30% 33% 33% 2 3.7 2.75 1.35 33% 31% 33% 28% 7 3.5 3.5 1.00 31% 28% 33% 28% 12 3.7 4.95 0.75 33% 28% 32% 26% Nominal -10 10.1 2.25 4.49 -7 11.2 2.5 4.48 2 11.2 2.74 4.09 7 11.2 3.7 3.03 12 11.2 4.85 2.31 Max capacity -10 10.1 2.25 4.49 -7 11.2 2.5 4.48 2 11.9 2.49 4.78 7 12.7 3.55 3.58 12 13 4.5 2.89 Flow 35degC temp output COP input output output input input % of nom. % of max. % of nom. % of max. Min capacity -10 6.2 2.75 2.25 61% 55% 61% 52% -7 3.9 2.85 1.37 35% 32% 37% 32% 2 4.2 3.75 1.12 38% 34% 34% 28% 7 4 4.45 0.90 36% 30% 38% 30% 12 4 5.85 0.68 36% 29% 37% 26% Nominal -10 10.1 2.75 3.67 -7 11.2 3 3.73 2 11.2 3.44 3.26 7 11.2 4.7 2.38 12 11.2 6.05 1.85 Max capacity -10 11.2 2.6 4.31 -7 12.1 2.8 4.32 2 12.5 3.17 3.94 7 13.5 4.55 2.97 12 13.7 5.25 2.61

Interesting application. Do your calcs include the cost of a 3 phase inverter?

That may be true for Agile but for Fixed the online application only asks for the MCS number from the certificate. My PV supplier has already done the DNO application.

sorry that's a GSHP - can't find a review for the ASHP ecoAIR+ EVI 4-20 but still highly impressive if using the same technology as the GSHP

top model quoted as 5-22kW. Highly impressive modulation range claimed 15%-100% looks very interesting and there's a review here https://www.fmb.org.uk/homepicks/heat-pumps/ecoforest-ecogeo-ground-source-heat-pump-review/#:~:text=Final verdict,an extension in the future.

Cosy is working for me now but yes I'm still waiting four weeks after install for an MCS certificate before I can export using Octopus Outgoing Fixed. Fortunately I'm able to use most of what I generate at the moment running the heat pump.

perhaps not so small really but was stated by the installer as designed to be a combination of both low loss header and volumiser, and there's a few resources discussing such as this one https://www.hvpmag.co.uk/Benefits-of-a-combined-volumiserlow-loss-header-for-heat-pumps/14295

Ah yes I see I suppose mine's doing similar but to a much lower tank temp and the average works out at a rate of 2kW

My understanding is that there is a subtle but nevertheless important distinction between a buffer and a low loss header/volumiser. The buffer is to give extra volume and longer run times but the low loss header is a small volume device, placed between the primary and secondary circuits, intended to give hydraulic isolation to the secondary circuit flow and stop it being disrupted by the primary circuit flow. At least that's what mine does. I have an 8mm microbore network feeding my rads aided by a second pump and it just wouldn't work without the LLH

Do you mean output power? Mine never draws more than 2kW and heats to my set temp in around 30 min, using an 11.2kW HP

That's exactly what mine does in WC mode or, if in target room temp mode set to 19degC, it goes to 20degC, switches off for an hour or two then switches back on again at 19degC. Today ambient temps reached 11degC so at a WC governed target flow temp of around 36degC (I have rads) my heat pump is running below minimum modulation level and comp pauses briefly around every half hour.

I've registered for this as it fits my situation quite well, and today called to check as I had no email acknowledgement. Good job I did as my Cosy registration triggered an automatic process to give me a new smart meter which I already have. Now they are aware of the issue hopefully it will prevent a log jam building up of unnecessary application processes to give all cosy applicants a new smart meter, whether they have one or not. But be prepared for a wait if you do register.

It's got some attractions. The morning period is not far off our current switch on and get up times. The afternoon period is the time of highest daily temps = best heat pump efficiency, and we still use gas for cooking.

https://saturnsales.co.uk/images/products/editor/Daikin_Altherma_3_Monobloc.pdf says inverter driven, and can do heating, reversable heating and cooling. Looks pretty impressive on paper - certainly the specs are up there with the other leading brands/models