Hi everyone.
I bought my EmonPi kit a few months back so that the Heat Meter could get installed in my house as it was being built.
I have just moved in and have been very busy but now I might be able to find the time to actually wire it all in!
my problems started straight away as the physical space I have is difficult.
It’s spread out over a few meters and I can’t find a spot where I can fit the EmonPi that all my cables will stretch too.
also I find I don’t really understand what each piece actually does ?
Firstly can I extend the cable clamp wire for the hot water clamp. I’m pretty sure the answer is yes but would like confirmation.
secondly how does the EmonPi actually monitor the electrical power? Does the unit that slots into the consumer unit do that?
if so That means I don’t need a CT for the main power input from the grid?
As CT1 port on the EmonPi is in use that leaves 5 more CT input ports free ?
So I can fit 5 more to measure various flows from inside my consumer unit I assume?
I had an EmonTX3 at my old house logging some power flows so I could use these to monitor the same on these ports I assume ?
Is the software on the EmonPi able to do this already or will it need modifying?
That’s I need to know for the installation for now I think .
Your main query “Can I extend the comms cables from heat meter and electricity meter to the pi” is Yes
I used cat5 cable because it is twisted pair and inexpensive - and because I had a reel of it.
My heat meter is extended by about 10 metres but I’m told ( when I asked a similar question on this forum) that it’s OK to extend by much longer than this.
The comms for the Din rail sdm 120 electricity meter is a bit more tricky because one end has to be inside your consumer unit and you must pull the wire through to the outside , so take care. But you can extend that with cat5 also. (In my case I used twisted pair screened microphone cable because I happened to have some kicking around).
Extending the DHW diverter valve sensor c.t. was a bit more trial and error. I needed 10m extension and found that I needed to use 3 pairs within a single cat5 doubled up to reduce the losses enough to make the signal readable at the pi.
Thanks David that’s very Helpful
I have worked out a way to do it if I only extend the DHW diverter valve sensor wires.
But it will mean i will have to buy all new CT 's with longer wires. As I understand it, it’s not an easy job to extend them so will have to either get them made up specially or find some ready made at the right length.
You should have a printed copy of the installation guide, you can download a digital version from here: https://files.openenergymonitor.org/emonhp-pi2.pdf. This should help identify the parts. I would recommend using the printed version since this one will be specific to the hardware setup that you have.
As mentioned in the installation guide, you can extend the MBUS connection to the heat meter and / or the RS485 modbus connection to the electric meters.
The usual setup is to install the emonPi next to the DHW cylinder with the heat meter installed close by, then extend the RS485 modbus cable to reach to electric meters which will probably need to be installed in or near the consumer unit. Retrofitting to an existing heat pump can be a bit more challenging than installing the system at the same time as the heat pump.
The Level 3 heat pump monitor uses inline SDM120 MID meters rather than CT sensor to measure power. It’s possible to use CT sensors if you prefer, but you would loose the MID approval. To use CT sensors to measure the power used by the ASHP you will need to add an emonVS voltage sensor: emonVS Power Supply: UK Plug - Shop | OpenEnergyMonitor. I would recomend using the SDM120s meters if possible.
But if you’ve still got the emonTx3 and the old c.t’s, the emonTx3 can still send its data to your emonPi2. (You can’t mix old c.t and new emonPi, or vice versa).
Thanks everyone for the replies I have made headway and i think it might be setup this Tuesday. House moving is a bit hectic ! and I might have a few more questions later.
But for now thanks again
I had an EMON PI2 installed downstairs to measure the power supply to heat pump via a CT clamp in a meter box nearby. I subsequently installed a heat meter in my loft some 15m away from the EMONPI I mistakenly thought I could run a USB cable between the two but this didn’t work. I then had a lightbulb moment when I realised I could use an old Raspberry Pi2 locally in the loft to link to the MBUS and record the heat meter data. I also had some data available from Home assistant integrations such as Daikin room temperature, target flow temperature and DHW schedule on/off etc. I then merged all the data from these three sources up to the cloud version of OEM and it is working a treat. No need to actually run wires between the various data sources.
Thanks Glyn using OEM and Home Assistant really helps fine tune the weather compensation and I think I have it about right at last. I had problems connecting the MBUS to the EMONPI 2 even when I moved it into my loft. I tried to connect it to the USB C on the EMON PI but this never recognised it. I tried exactly the same with an old Raspberry PI and it worked first time. I was told the EMON PI 2 USB C is not available for connection to the MBUS. For future reference how should you connect MBUS to an EMONPI 2 if it doesn’t have a USB port to plug into ?
HI again
I am still not absolutely certain how to Install the electricity meters into the consumer unit.
I have got round the initial problems of physically fitting them and
when i look at the wiring diagram it makes complete sense, Just wire them in series!
I don’t like wiring in consumer units much, so not so confident.
I don’t want to muck it up!
Looking at the diagram I have to re-route the power from the output of the trips to the input of the electricity meters and take the live output back to the pumps is that correct?
That all looks fairly obvious but I just want to make sure.
It means adding a link from the out put of the trip to the input of the energy meter but I’ve never seen this done in a consumer unit before.
The emonPi2 has 4x USB ports, you can plug the MBUS adaptor into any of these ports. Be sure to configure the MBUS section in emonhub according, if setting up a non-pre-provisioned system. The Level 3 bundle purchased from the shop is fully pre-provisioned and pre-wired to be plug and play.
I would recommend you consult an electrician to undertake this work. I’m sorry, I feel uncomfortable giving remote advice on mains wiring.
How? If they’re on a separate DIN rail and not connected to any busbars, then it’s probably easy enough. A good, clear, well-lit, sharp photo showing all of the inside of the consumer unit will help.
Thanks Glyn, I don’t think I have a full EMONPI 2 as there are no USB ports on mine ! I was supplied with this EMONPI via a heat pump project with Nesta/Octopus to monitor and control heat pumps remotely. The OEM unit was there to monitor the power supplied to my heat pump. Having got this I then bought the heat meter separately from you direct.
Hi @PhilBroggio - as noted in the title, you are using a RasPi Zero 2W which doesn’t bring out the USB ports. If you have one spare, any Model B style RasPi (I’ve included a shot below, that’s the RP4) will fit in there and expose the USB ports. In principle, you could swap your existing SD card into a RasPi 3B (the SoC is roughly the same), but realistically it’s probably better to start from fresh.
Hi Sorry for not replying before. As I said I’m in a bit of a mess with moving house and I’ve not had much time to devote to this install.
I Got my electrician who was fortunately working in the the house getting built next door to have a look and he just removed a section of the Bus Bar. I later also persuaded him to install my energy meters so that is all working and I am now ready to get into the emoncms website. The EmonPi has connected after i fixed a ethernet problem and it’s looking good. Except I’m following the setup help but can’t find the emonHub anywhere?
That’s what I was afraid of. I think you’d connected the meter with no overload protection at all! (not counting your supplier’s 100 A fuse).
You really need to know what you’re doing before you go inside a consumer unit.
(I’m a Chartered Electrical Engineer, not an electrician )
It’s software. It should be installed on your SD card. So it’s running as part of your emonCMS on your emonPi - there isn’t an emonHub at emoncms.org because it doesn’t need one, that emonCMS gets all its incoming data via the Internet. emonHub handles the serial and USB ports on your local RasPi Zero 2W.
You need to be clear which emonCMS you’re talking to. They look much the same, but they are totally independent, there are differences in the software versions and facilities offered, and they have different passwords and APIkeys.
Thanks Not sure if you are saying the electrician has not done the right thing in removing the bus bar? what should he have done? I’ve paid him and he’s gone now!
Yes I am getting to grips with the fact there are two Emoncms’s but I can’t login to the local one! I have tried but in the help it shows a registration button which does not appear on mine. I can’t use my web username and password as it doesn’t work.
So at the moment I’m trying to work out how to get into it.
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