How to read power consumption from the heatpump

[daneedk]

Hi,

I've successfully setup an M5Stick C Plus 2 to read data from my Altherma 3 heatpump and able to receive information from it. I did all this to be able to read the power consumption, but unfortunately the Current measured by CT sensor of L1 returns 0, just as the ones for L2 and L3.
Searching around learned me that this is because this feature was never installed in my heatpump.

So, I've googled a lot and found out I can put a Smart Meter (Eastron SDM630 for example) in the power in feed an connect the pulse signals from it to X5M connector (pins 5 and 6) and after some configuration the heatpump should know about the power it uses.

So far so good, so here's my question: Would I also be able to read those values with ESPAltherma?

Why do I want them in ESPAltherma, why not just read the MQTT data from the Eastron SDM630?
Well, I use the Homey smart home platform and there's only an app that connects to the Daikin Onecta cloud platform that hardly returns any information, no power usage for example, and has a low limit on the number op API calls you can do.

That led me to ESPAltherma, only to find out I also can get no power readings.
I've already written an app for Homey to consume the data retrieved from the ESPAltherma and display it as a capability and insight (graph) and being able to show power usage I'd have to have the usage inside the app.

Anyway, I hope this makes sense and someone can answer the question: Would I also be able to read those values with ESPAltherma?

Cheers!

[divenal]

It ought to be easy to count pulses with a GPIO pin on an esp32 - it does the counting for you once you've configured it correctly. So you could connect the pulse output to both an input on the esp32 and on the altherma. Provided the voltages are compatible, of course.

[daneedk]

Thanks @divenal,

Never thought about feeding the pulse straight into the M5Stick, that may even be a better option as the documentation from Daikin isn't to clear on what connecting the pulse into the Altherma would actually achieve, so maybe it's better to just keep it out of the Altherma all together.
Also not sure what it would take to get it connected to the M5Stick, but I'm sure I'll be able to find a schematic, I'm pretty sure I won't be the first to try this ;)

[daneedk]

It's working! I've written the code and although I still need to order and install the Eastron SDM630, the ESPAltherma part is done!

The code can be found on my fork here: https://github.com/daneedk/ESPAltherma/tree/own

The Eastron S0 port is essentially a potential-free, momentary contact, so I simulated this by intermittently connecting the M5StickC Plus 2 GPIO 33 pin to GND.

When I've received the Smart Meter and have it installed I'll do the final testing and send in a Pull Request.

[smurphy917]

Curious (once you install the PM) what differences you see from the meter vs just doing a basic calculation using the INV primary current (A) value from the ESPAltherma. Particularly curious as this is the value used to determine COP for many of us.

[daneedk]

Yes, I'm also very curious of what I will find.
As I understand it, the INV primary current (A) value is from the DC side of the heat pump. I wasn't able to find out how to translate (or calculate) this into an Energy Consumption and or COP so I'm very interested in the calculation you use!