gascounter-zigbee

Voraussetzung: Homeassistant mit Zigbee2mqtt Thanks to u/Andyrew

Zigbee Gascounter m³/kWh

The idea ...

With the possibility to display energy consumption in Homeassistant, I wanted to enable and display a long-held desire of counting gas quantities.

As always, the Internet helps

History

About 10 years ago I had already tried a solution from ELV with an optical eye. At that time, however, it failed to meaningful representation of the CSV data, which was quite tedious. A radio station with data collector, which one had to read out every week, made no joy. Whereby the optical number change certainly already worked well.

Internet search ultimately with success.

Admitted masses I have searched for this about 2-3 years ago on the Internet and found nothing clever. Maybe the search was not serious enough. Then I found the link in Reddit Tutorial: My gas monitoring solution with Home Assistant and Zigbee from "u/Andyrew". Perfect, some Homeassistant scripts and links to STL files are included.

The Idea

A good thought

While reading the Reddit entry and after looking at the STL models, an idea came to me very quickly.

Wait a minute, you still have some door/window contacts in the drawer, surely they have reed relays since they respond to magnets.

Beta Test

Quickly a door contact was dismantled and placed with double-sided tape in the trough of the gas meter.

To my surprise, it already worked perfectly, I could compare the ticks in the Homeassistant with the meter reading over an hour, fits.

Experience after months

Battery life

I started with it in November 2021. Until today, October 2022, it works without battery change.

Measurement precision

Every 1st of a month, I record the gas meter readings by hand. On 1/1/2022 I had the value of 54.430 m³, in the dashboard of the Homeassistant I entered the value 0 (zero). On October 1st 2022 the B-G4 value was 54.430 m³, the dashboard showed 1.354 m³.

Let´s calculate

Device	on 1.1.22	on 1.10.1022	Diff
BK-G4	54.430	55.764	1.334
Homeassistant	0	1.354	1.354

If I subtract the value 1.354 from the real BK-G4 value i get 54.410 m³. So the Homeassistant value is 20 m³ lower than the real value.

20 m³ are 20.000 tiks delta. We had 1.354.000 tiks.
1 m³ is about 10kWh. If i calculate 15 cent (take your values) per kWh ist is 20 x 10 x ,15 = 30 EUR.

The difference can be determined, but in my opinion it is negligible.

Some Codeing

Great thanks to u/Andyrew

Thanks again to "u/Andyrew" for the clear Reddit entry.

Running System

For the sake of completeness, here is the code I have running, stored in files in this git.

Screenshot Dashboard.

In the input fields displayed, one simply enters the gas price in cents and the average daily price of a basic charge.

With the Homeassistant energy dashboard, for example, you can display the hourly gas consumption from the Utility Meter gas_hourly.

Discussion about the formula price calculation.

In the Reddit entry, the formula refers to the British gas tariff, which does not quite fit here.

In Germany you just have the cent amount per kWh and a monthly base fee.

In addition, the m³ must be multiplied by a changing calorific value, which can only be estimated or read from the pricelists. From my experience, however, it changes in the second decimal place.

Also, it may be questionable to convert a monthly base amount to the day, the hour or even the quarter hour, Well ...

Formula example Look at the files in this git.

Code m³ add

service: input_number.set_value
data_template:
entity_id: input_number.gas_meter_m3
value: '{{ (states.input_number.gas_meter_m3.state | float ) + 0.010 }}'

Calculate calorific value code

gas_meter_kwh:
device_class: gas
unit_of_measurement: "kWh"
value_template: "{{ states.input_number.gas_meter_m3.state | float * 9.5 }}"

source code temporal calculation

gas_price_hour:
unit_of_measurement: "€"
value_template: "{{ (((states.sensor.gas_hourly.state | float * (states.input_number.energy_gas_unit.state | float /100) ) + (states.input_number.energy_gas_standing.state | float /24)) ) | round(2) }}"

Values Meaning

{{ (states.input_number.gas_meter_m3.state | float ) + 0.010 }} = One rotation of last counter disc is 0.01 m³
{{ states.input_number.gas_meter_m3.state| float * 9.5 }} = Convert counted m³ approx. to kWh
states.sensor.gas_hourly.state | float = Hourly value kWh
(states.input_number.energy_gas_unit.state | float /100) = Cent value normalized to EUR
(states.input_number.energy_gas_standing.state | float /24) = Daily base fee / 24h

3D Print for Doorcontact

Adapt the STL file.

Based on the link in u/Andyrew's Reddit entry, this just needed to be adjusted so that just the small door contact MCCGQ01LM fits exactly under the gas counter disk with the magnet.

Adapt door contact

You have to shorten the board a little bit on the side with the antenna until just before the antenna. Then it fits exactly into the 3D print and this to the gas meter. However, I have constructed this somewhat quickly in Tinkercad, here is certainly still potential for improvement.

The STL Files is in this git. The link to the STL file with reference to the original shape is here BK-G4 Gas Sensor Count with Door Sensor MCCGQ01LM

Nice and easy!

Value for money

For maybe 10-15 EUR you get a highly accurate gas meter.

harryinet/gascounter-zigbee