I’ve been reading about some of the advanced users on here optimising their heat pump efficiency and I’d like to do the same.
I’ve got a pair of 12kW Ecodan units connected to FTC5 controllers that were installed in 2016 and I’m sure they could be running more efficiently. Last year we consumed around 30k kWh of electricity, the bulk or which is attributed to the Ecodans (a little EV charging in the mix), we’re heating circa 5k sq.ft. of 2016 new build in the South East of England for reference.
I’ve recently had the system serviced by a Mitsubishi engineer who found some issues with the original installation and now would seem like the ideal time to add some additional sensors etc. if I’m going to have the remedial work done.
As I understand the system only has the basic (EMP1?) monitoring package in place (no RHI as new build), I upgraded both units with the WiFi interface last year so I can monitor/control through the MELCloud app/API.
Monitoring/control equipment wise today I have the following;
- 2 x FTC5 Controllers with WiFi modules
- emonpi and emontx with pulse sensor (recording PV generation) and CT sensors
- 3-Phase smart meter connected to Glowmarkt Bright app/API
- Home Assistant (using integrations to connect emoncms/melcloud/glowmarkt etc.)
I’m pulling some data into emoncms via the MELCloud integration for Home Assistant currently, such as flow and return temperatures plus outdoor, indoor and hot water temperatures.
What would you guys recommend I add to my system from a monitoring perspective? Flow meter(s)? Heat meter(s)?
Also, should I go Mitsubishi EMP3 or home brew? I’ve had some (ongoing) issues with the Mitsubishi cloud service as both units intermittently stop updating the flow/return and hot water temperatures in the MELCloud app, so I’m swaying towards being self-sufficient.
Hello @Dan_Nichols what are you able to tell from the data at the moment? can you see flow temperatures? do you have a CT from the emonpi/emontx that can isolate just the heat pump component? What do the graphs look like?
You should be able to get a lot of insight with what you already have, maybe enough to do some optimisation? It’s obviously nice to have heat metering as you can then accurately measure COP and so more easily monitor the effectiveness of optimisations but it’s not necessarily required.
I would personally do a separate system to the EMP3 as you can then pull out more data from the heat meters via MBUS and at higher resolution, there may be some scope to do both with the same heat meter, I think the Mitsubishi system uses the pulse output from the heat and electric meters, I may be wrong about that. You could then have the data both through MEL Cloud and seperatly via MBUS direct to a Pi… You’d just need to make sure that the heat meter and electric meters have MBUS outputs…
Hello @TrystanLea, thank you for taking the time to reply. I’m not able to tell much at the moment as I’ve only just realised I can export some of the MELCloud data to emoncms via Home Assistant and I’m suffering with the apparent MELCloud API throttling issue that I’ve seen a few of the members on here discussing. I’ve tweaked the Home Assistant MELCloud integration to reduce the API calls from 60 to 120 seconds so once they start updating my data (stopped around 20:30 last night) I’ll see if that gives me a more reliable data feed.
The heat meter feels like a good step forward as I’m in for a few £k of upgrades to get my system on the Mitsubishi diamond cover anyway. Any suggestions on what heat meter model you would recommend and exactly where in the system this should be installed would be appreciated.
The engineer also mentioned that the type of flow meters I have installed at the moment can be problematic down the line so I might look at replacing those (although they may be covered under the maintenance contract in future).
What type of electric meter do you recommend? I’ve been using some 100A CT clamps with emontx which I don’t think are very accurate - I’ve got two side by side reading ~50-100W apart most of the time and another that appears faulty and stopped reading altogether. Perhaps it is because they are too large for the application? (thin wire with large CT clamp)
My recently installed Ecodan has the Sika Vortex meter. The FPC 6 is reading an analogue voltagd output. Ive piggybacked a ESP8266 NodeMCU onto the output (directly as the max is 3.6V, but thats for unachievably high flow rates - normally its about 1V) and im powering the ESP8266 from 5v flow meter supply. Im then sending that direct to Emoncms. It seems to work!
Hello @Dan_Nichols, we’ve written a piece on selecting the right heat meter here HeatpumpMonitor/selectingheatmeter.md at master · openenergymonitor/HeatpumpMonitor · GitHub, do you have a diagram of how the system is plumbed together?
I’ve been using the SDM120 electric meters for class 1 metering with heat pumps, you can read these with either modbus or mbus depending on which variant you order.
@Rachel that’s a nice solution, @Dan_Nichols do you by any chance have any Sika vortex flow meters on yours already? Looks like this:
Hi @TrystanLea, thanks for the pointers, and your very informative article on choosing a heat pump. I’m still waiting for the Mitsubishi appointed installer to quote me so no progress in that regard as yet unfortunately.
I don’t have a heat pump installed in my system sadly and I’m still having issues with the Melcloud API intermittently refusing to refresh the hot water temperature (which still happens with a five minute gap between API calls). I think I’ll have to try Mitsubishi support and see if they can offer any insight.
I’ve been having a read through @MyForest github repo to understand his control logic and see what I can implement via homeassistant/nodered as an alternative controller. Going to be a long road but interesting none the less and more incentive than ever with the forecasted price of electric this coming winter.
I’ve finally got an installer lined up to upgrade my systems and am intending to have a pair of Sontex Superstatic 449 heat meters installed with MBUS capability.
They are available in QP1.5 and QP2.5 models which I believe relates to the nominal flow rate they are designed to measure. QP1.5 I believe is 1.5 m3 per hour which translates to 25 l/min and likewise QP2.5 is 2.5m 3 which translates to ~41 l/min. Max flow rate is quoted as 3 m3 (50 l/min) for the QP1.5 and 5 m3 (83 l/min) for the QP2.5 models.
My Ecodans are PUHZ-W112 which are specified for between 14.4 - 32.1 l/min so I believe the QP1.5 model is most closed suited to my requirement?
Before I invest the £4.5k its going to cost me to ‘upgrade’ my system (i.e. fix issues with the installation and upgrade to include heat meters) is there anything else I should consider and where should the heat meters ideally be installed in the system?
Thanks in advance for any advice, the various installers out there don’t seem to either know these systems well enough or have the time/inclination to discuss such details.
My Ecodan 14kW unit is awaiting final commissioning and following the advice above and elsewhere, I’ve installed an SDM120 modbus meter on the supply and a Sontex 749 (QP2.5) mbus on the return flow pipework.
Both feed into my emonpi and are operational even though the heat pump isn’t!
Hi Nick, thanks for your reply. I hope that the advice from the experienced users on this forum means you’ll end up with a system that works from day one! I inherited my systems nearly three years ago and have only recently been made aware of some of the issues with the initial installation (such as low flow rate on one system).
Any reason you’ve selected the Sontex 749 over the 449? Same question regards going for QP2.5 over QP1.5? I believe your 14kW unit runs in the 17.9 - 40.1 l/min range which I believe the QP1.5 is designed for, is bigger better from a monitoring perspective? I gather the flow restriction is marginally reduced on the QP2.5 model.
I’m going to add some additional power monitoring (likely the SM120) alongside the other system upgrades I’m having done.
Just so you can compare, I’ve got three pumps (as you’d expect) and here they are.
As you know, I don’t run them continuously. I claim it’s due to the noise and efficiency but really it’s just because it seems pointless to keep running the water round and round the circuit. To be honest the noise is fine in the utility room. It would be annoying in a bedroom.
Spider webs were installed later.
Mitsubishi tank diagram
Mitsubishi pump curves
MMSP hardware that my installer fitted.
I’m not measuring the flow speed, it’s not reported in the MMSP package on MELCloud.
I can say “it’s not broken” but I haven’t tried tinkering with it to see if I can improve it.
I know we often ask “is the flow fast enough?” but I swear even John was asking if a fast flow was always a good idea, but I can’t find it. I’m not going to “at” him here, but you may if you wish. I’ve bugged him enough over the last couple of years.
I went for the 749 as it is cheaper and does everything I need. Don’t mind changing the battery every few years.
Size wise, given the flow rates for the Ecodan were still in the range of QP2.5, I went for that on the basis of marginally less flow restriction.
Thanks for sharing David, one of my systems is running at a flow rate of 14 l/min (according to the most recent system inspection) which is just below the acceptable range for the unit so the the flow sensor has been disabled to stop it throwing errors. To resolve this I’ve been advised to remove a couple of flow restrictors from each manifold (see attached picture - these reducing valves are installed either side of each of the two manifolds) and upgrade the primary circulating pumps from 25-40/60 units to 25/80. I’m slightly concerned that there is more guesswork than calculation in this proposed system upgrade though.
I have also included a picture of the manifold installation which is a bit of a dogs dinner by all accounts. Should I be re-plumbing this rather than simply removing the flow restrictors?
If anyone has any advice on how to model the improved flow with the restrictors removed and upgraded pumps I would appreciate the input.
The second system is reportedly up at 20 l/min which is within the recommended range (albeit at the lower end).
I would imagine there is an optimal flow rate which likely varies depending on lots of factors specific to each installation but would be interested to hear others thoughts and experiences.
If you do rework it, fit some sensor pockets so you can fit some temperature sensors easily
I’ve got temperature sensors on the primary flow and return, is there a need to add additional sensors to each manifold, or is it a nice to have?
Probably a nice to have, but if you are taking the piping apart, my view is to always fit pockets even if you end up not using them! You can’t have too much data IMHO.