Is there an affordable multi-channel power monitor?

Hardware
1

Hi,

I’d like to monitor the power usage of several parts of our oil heating. Internally, there are four different parts connected to 220V. Probably oil pump, water pumps, electonics, oil preheating… haven’t looked into it in detail yet.
I expected this to be easy - just insert a 4-channel smart switch with power monitoring. Except - I did not find those. There seem to be very affordable 4-channel smart switches without power monitoring, like for example the Sonoff 4chr3. And there are 1-channel smart switches with power monitoring. But no combination of those, or I just missed it.

Is there a current/power sensor, that could be used to connect several of them for example to an ESP running tasmota?

2

I know affordable is subjective but these are 2 good options.

Shelly with switch control and power monitoring per channel

Or just power monitoring without inserting into circuit.

https://www.amazon.co.uk/3-Phase-Emporia-Electricity-Metering-Conserve/dp/B086BNQ1X4/ref=asc_df_B086BNQ1X4/?tag=googshopuk-21&linkCode=df0&hvadid=570407010710&hvpos=&hvnetw=g&hvrand=1910437146687156338&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=1007136&hvtargid=pla-901368461408&psc=1

1 Like
3

Three of four of those loads could be problematic. (high amperage and/or inductive) Those are motor and induction loads - before buying ANYTHING be sure you know if the switch / relay can handle the inrush current. (you need to know volts, amps, number of phases, run current and startup current and your switch needs to be able to handle all of it. With heavy motor loads Iike those pumps - inrush can destroy the capacitors in smart switches and relays if they’re underrated.

Its still doable but garden variety gear rarely works here. You’re probably looking for clamp style meters rather than smart plugs look for ‘HEM’ devices like Aeotec smart meter.

Get all the specs before you start purchasing.

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4

I looked at those Emporia sets. Looks like good hardware at a reasonable price. I’m concerned that they are cloud-based. There have been a few threads here talking about ways to flash them using ESPHome, among other solutions. Here’s one.

It’s a pretty big investment to just buy and hope for the best. I’d go that route if I had any confidence that I could get it working locally.

5

I figured, that the price for a four channel switch with power monitoring should not be that much higher than the version without it. Or, to put it in another perspective: in the range of two two-channel devices, like for example two Shelly Plus 2PM. But something like this doesn`t seem to exist.
(maybe I could use two of those dual-channels, but the power usage of all those smart switches is adding up…)

And you are right, the Shelly Pro 4PM and the other meter are viable options. Thank you.
I probably won’t buy one of those now, but consider them next time.

For now, I am also looking into the PZEM-004t, saw that there are people who managed to connect several of these to a single ESP…device.
(But I am wondering, how much power one of those modules would be using for itself.)

6

Thanks for the reminder.
The heating system (one-family-house) uses high efficiency pumps, IIRC their nominal power should be below 30watt. I know that the inrush current can be considerably higher, but I have to admit, that I have no idea how much higher.

1 Like
7

Up to 100x

8

I’ve got a combination of EmonTx (www.openenergymonitor.org ) and IotaWatt (www.iotawatt.com ). Both reporting to a local EmonCMS. Then there’s an EmonCMS integration with HA… however, I’ve not been able to get the usage graphs I’d like out of HA - so I ended up embedding the ones from EmonCMS.

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9

I should not have looked at this… now everything else seems inadequate…
(of course this would be not only for the heating system, but for the house.)

Unfortunately this is too expensive for me at the moment. But since there seems to be the possibilty of a future version of iotawatt with ESP32 and with even better ADCs, I would want to wait for this anyways.

So for now, I will probably go for some solution with the PZEM-004t modules or with one or several Shelly devices.

Just for background information:
The main reason I wanted to monitor different parts of the heating system is, that there are problems with it. It belongs to my fathers house, and it sometimes stops with an error message. He already had to pay several thousand Euro to the professional serviceman, who also mainly seems to change part after part.

And there are problems not only with this system, but with another one, too. The heating of the nearby church community center had even worse problems, until now there have been four different companies working on repairing it.
It was the reason I started with Home Assistant: First I installed several temperature sensors, so I could see it from my home, if the heating failed in the community center. Then I build and installed an automatic physical button-presser to restart the heating system. (heating stopped with error-code, if you pressed a specific button on the device in the basement, it restarted).
If the temperature sensor was below a certain value for some time, a home assistant automation activated my physical button-presser. This prevented the building from going cold for several weeks.

Seems like they have found a company than can fix this heating now. But since the complete heating of the community center is a frankenstein-monster, partly enhanced or modernized in differnt decades, with the parts not seeming to be fitted very well to one another, it still might be interesting to see the pattern, how different pumps are activated during the day.

Of course, energy monitoring would be interesting in other aspects as well. I plan on installing some small photovoltaics, too. Since I would have to try to use the solar energy, instead of feeding it into the grid, it would be good, if the big freezer in the basement as well as the water heater could mainly use the electricity during the day and avoid the night as far as possible.
Monitoring the complete house might also make it easier to evaluate the amount of engergy that devices on standby or all those power supplies are wasting.

10

Yes, cheap (around $10) and still (very) precise are the pzem004t v3. (max 100A :warning:) :point_down:

You can wire multiple of these to one esp and they offer a housed version of the pzem004t v3 too :ok_hand:

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11

Do you know if the emonVs (voltage meter for the emonTx V4) can read the voltage for multiple lines (2 in my case for 1-phase service), or only one line?

12

Hi @Odwide, I don’t have one of those (my system pre-dates their availability). But my guess would be no, it looks like it’s just supposed to plug into a normal, single socket. You are wanting to measure a US split phase setup?
You might be able to plug it into a US 240V socket & halve it; you’d be measuring the average of the 2 phases - maybe better?

13

Thanks, @blaal02. Yes, for US split phase. I reached to the OpenEnergyMonitor folks and they said that the 3-phase emonVs can be used to monitor each line. In that case I’d power the emonVs from the panel instead of plugging it to an outlet and on the sketch assign each line to its respective CT.