Anyone monitoring a new R32 Ecodan?

Hi , I have been monitoring out new Ecodan 14kw R32 unit - today I did an experiment in continuous running - I cranked the room stat (Nest) right up so I could be sure it would not try to stop the heatpump. In all it behaves pretty much as I would expect - there is a bit of overshoot on startup - on this occasion it ran through it but on other times it has caused it to stop - once it gets past this it seems pretty steady away - I stepped up the flow temp setpoint from 40 - 45 - 50 as well as twiddling a bit with one or two radiators and it all behaves itself I think.

Im a process/automation engineer by trade and have spent more than a few hours staring at trends of various processes and tuning PID control loops etc - I don’t know if the mitsubishi allows you to adjust any of the PID parameters (assuming they use PID control) or maybe they have some auto tuning thing going on - if not then I guess they will have set it up for an average situation - the main things that will affect how it reacts will be process deadtime and the time constant - i.e how long does it take from making a change before the controller sees the temp start to change and how fast does it change once it has started to move - both of these will be installation dependant - so I guess some will be better than others.

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I would add that long deadtimes tend to make the process harder to control - imagine trying to drive a car with seconds of turbo lag. So presumably heatpumps miles down the garden with the temp sensors mounted in the house will struggle to settle more - having said that ours is about 10M away from the house and seems to be OK.

Always interesting to see graphs… I would like to see how it settles at the minimum end before it decides to stop. looks like it was a bit under 6kw at the start.
I know nothing about the control but someone told me that Mitsubishi Mr Slim Air Con protocol was freely available… No idea if that could relate to Ecodan, but he thought it did.

Hello John

So I reduce the flow temp down to 35 Deg to see how low it will run. The first half of the trend below is doing a hot water cycle - after that it goes back to 40 Deg Flow and shortly after that I drop it to 35 Deg C - you can see it starts to cycle . To be fair the heat pump data plate indicates an output range of 4.5 - 14kw - and at the end of the trend the simulated heat output is 4.8 Kw - so give or take some errors it seems about right. One of the off periods the circulation pumps stopped - so I think there is a lower flow temp limit set by the installer - when I increased the setpoint to 36 it kicked off again.

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Many thanks, yes it does seem to do about what its says on the tin. My 6kW is supposed to go down to 3kW, but I have never seen a level straight line anything like as low as that.
There is a Flow Temperure limit. Default min is 30C but this can go down to 20C.

2 posts were split to a new topic: How should I monitor a EcoDan heat pump?

Gosh, the 6kW Vailant Arotherm Plus heat pump the heat geek folks are using seems to modulate down a very long way:

https://emoncms.org/heatgeek

It appears to be consistently capable of running consuming just 440W and producing 2.3kW.

Although we can see it does have to turn off because even it can’t modulate down low enough to stay running all the time.

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My Ecodan 8.5kW seems to have a minimum power input of about 650W - my elec measurement here includes 2 circulating pumps. But oddly it sometimes seems to prefer cycling at slightly higher power than running continuously at minimum. (Also, my CoP isn’t quite that good- i need to change my flow calc, but its in an Arduino and i havent got round to it yet!)

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Interesting to see these graphs. According to the databook, the heat output should drop well below 4kW at your conditions. I have been emailing Mitsubishi since February, but not yet had an answer. My hunch is that whilst it seemed correct for the older R410a models, the newer models don’t drop to the minimum on the spec sheet.
image

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Hi John
There is a databook for the R32 ecodan which presumably superceeds the older one - have you been using this?

I’m just about to post a python program that I have been working on which essentially incorporates and interpolates the data from the databook into a function that will return expected heat output for a given set of conditions - i.e input power , flow temp and ambient temp. I have managed to integrate it with my emonpi so I can show the result on the heatpump app and compare with the carnot value. Ive used the data for a 14kw unit but if you have the patience to type in the data for a smaller unit it should work the same.

It has certainly made the penny drop about the importance of reducing pumping power to the minimum - since intitially I forgot to account for this and was getting very high cops - I assume the data book is just for the bare outdoor unit and has no allowance for circulators etc.

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I thought that too, but looking at the performance chart for my model (PUZ-WM112VAA) for a given ambient temperature, the COP is actually higher at a medium power than at minimum. It looks to be the same for the 14 kW model too, yet small models see higher COPs at the minimum power.

image

I’m also not getting anywhere near these numbers with the system overall, including power to the pumps and losses along the pipes. I’m seeing COP about 0.5 below what’s shown in the databook.

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It’s a 5kW unit, same as mine.

Yeah, mine regularly runs at 500W for 2.4kW / 2.5kW output

https://emoncms.org/energystatsuk

My installation needs it to drop to 7C or below for it to start to run long.

There’s a 7kW Arotherm Plus on the monitoring list that can do 600W low for 3kW too
https://emoncms.org/app/view?name=My+Heatpump&readkey=8e2d4547934319f9151a4730fb3e9f21

Although if you want LOW, Glyns 5kW Samsung can do 400W for 2kW
https://emoncms.org/samsung5kw

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I’ve fixed my flow meter error today and added my heat pump to the monitoring website.
It’s available here: Emoncms - app view

I’ve also hooked up a Shelly IoT device to the ‘demand management’ contact; initially so that I can programme it in advance to switch off suring Octopus demand management periods, but maybe also to provide some better control in warmer temperatures - i.e. turning it off for while.

R

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Hi Rachel - It would be great if you could share a bit more detail about how you connected your Sika flowmeter - I see it mentioned on several threads but no exact circuit diagram or terminal details on the FTC controller as far as I can see. I did investigate with a scope but managed to put the scope earth on the +5v dc supply to the flow meter pulling it down I think which stopped the heat pump and nearly stopped my heart pump too - luckily both recovered OK - but now a bit nervous to poke about. I am currently calculating heat output based on delta T and an assumed flowrate based on the reading from the FTC controller , not sure how accurate this is though. Are you making any allowance for glycol in your calculations and temperature effect on viscosity etc?

I was pretty nervous too, it was necessary to poke about with a multimeter to figure out which was the signal/gnd etc on the cable! I’ll try to do a quick sketch at the weekend…

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Hi, Here’s the hook-up arrangement. Use at your own risk obviously :slight_smile:
SikaFlowMeterHookUp.pdf (207.9 KB)
FlowMeterSketch.txt (3.6 KB)

Hope you don’t blow anything up…

Rachel

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Thanks Rachel
I will have a look when I’m feeling brave
Mark

Can you share how you have set up control of your Ecodan 8.5kW and any settings you have changed?
Looking at how it is behaving it is doing a good job of continuous heating at a low level so would be interested to compare why our work’s office unit (same model) isn’t doing this.

Thanks for this Rachel, its useful to have detailed descriptions as starting points for those of us who bring zero experience to the task of setting up monitoring electronics.

You went route 1 and physically intervened in the wiring system. A less drastic solution was hinted at in another thread and has been expanded on by @TrystanLea in the documentation here: EmonTx4 Heatpump Monitor — OpenEnergyMonitor 0.0.1 documentation. The photos in part 3 show wires, doubled-up for some reason, in the block below where the Sika flow meter is plugged into the board. This bit of the technical docs shows the layout of the blocks at the bottom of the board and the reference to the flow meter at both locations – apparently allowing the Sika connector signal to be read from the lower block (I’m guessing that if you fit heat meters to the pipework this is where the flow data cables are wired in?).
FTC6 board.pdf (642.3 KB)

So far I have only got monitoring on the CU end of things, giving me the power consumption of my 8.5kW unit (which unlike Rachel’s seems to have a minimum working draw of around 1kW resulting in a lot more cycling unless it is decidedly cool).

I have yet to install at the cylinder unit end as I am still working up to the confidence to commit to programming an arduino-based solution to cope with several analogue readings and driving some 5V grundfoss sensors on the solar thermal. But soon, soon, …

In case it’s of some help to anyone: I can confirm that part of the TBI.4 block at the bottom of the FTC6 panel is wired in parallel with the flow sensor’s connector. I have a setup similar to Rachel’s, but measuring the voltage of pin 3 on that block relative to ground (pin 2).

I should probably introduce myself! I have had the 11.2 kW packaged unit installed for a bit over a year. I’ve noticed similar cycling issues to those discussed further up the thread, and have been progressively adding more monitoring to try to understand why it does this, given that you can see that it’s capable of modulating down far enough to avoid it.

Quite often the system gets in a cycle of ramping up aggressively, overshooting its target flow temperature, then abruptly stopping (or dropping to minimum power), waiting for a few minutes, then starting again. To me it just seems like a software problem: the hardware clearly could run consistently at an appropriate intermediate compressor speed – it’s just that the control system fails to find this speed in many circumstances.

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