Simple, no soldering or programming gas meter interface

If you, like me, have dumb energy meters with no sign of your energy supplier changing these for smart meters anytime soon, how do you get you energy usage data into HA?

Below I show you what I have done to successfully get my gas usage from a dumb meter into HA for anyone else to copy for themselves if they so wish. I recommend using Frient energy interface meters but I have no association to them and make no gain from this. It is just my personal opinion. They are not cheap but a nice, self contained battery powered solution.

Well, firstly I bought a Frient Electricity Meter interface. It is battery powered, zigbee and comes with a magnetic optical sensor to just pop over the led on your electricity meter and hey presto, accurate electricity consumption data in HA. This worked brilliantly for me using Z2M and I wanted to find a similar solution for my gas meter.

I noted that the Frient has multiple modes for electric, gas and water meters but it seems Frient only supplies the optical sensor for electricity meters and you cannot buy the other sensors anywhere. However, this sensor just plugs into the main battery/circuit box, so I thought I could make something to replace this sensor for gas meters.

I had seen many people doing things on gas meters with reed switches (and this maybe will work for you on this Frient) but I thought that a hall effect sensor maybe the better way to go as they are more sensitive.

I didn’t want to go the esp32 route either as have limited time to mess with this to get it working and I wanted battery powered in a nice enclosure.

So below, is what I built and it has now been operating for a few weeks integrated to HA and the meter reading and my utility meter reading in HA are spot on aligned.

I tried a couple of different hall effect modules and the first one did not work very well and tended to detect more use than actual, due to a short pulse after each long one (no idea why!). Anyway, the module I recommend from Amazon (priced at about £3) works really well with this Frient device.

Shopping list:

Hall effect sensor module - https://amzn.eu/d/93KKLG8
Cable - Amazon.co.uk
Jumper wires - Amazon.co.uk (although you only need 3 if you already have them)

Connecting

Connect your hall effect sensor as per the below diagram and plug into the Frient sensor socket.

Setting up

You will need to modify the pulses per kWh setting on the Frient to 100 from the default 1000. If you have set this sensor up in Z2M, you can change this setting, along with changing to Gas mode in the exposes tab for the device.

It is also worth noting that the HA sensor created shows a reading in kWh due to the Z2M device description only using these units. However, what this sensor is measuring is m3. You will need to modify the sensor UOM or create a template sensor with the correct UOM. I also created a template sensor to convert this m3 into kWh using the details from my energy bill and used this in my energy dashboard.

- name: "Gas Meter kWh"
  state: >
    {% if is_number(states('sensor.gas_meter_energy')) %}
      {{ (states('sensor.gas_meter_energy')|float * 1.02264 * 39.4 / 3.6) | round(2) }}
    {% endif %}
  device_class: energy
  state_class: total_increasing
  unit_of_measurement: kWh
  unique_id: 9999000002

Positioning on the meter

I just used some blu-tack to stick this to the meter over the last digit dial. The hall sensor module has an led that will show the on/off pulses as the meter digit revolves which greatly helps setup. However, see note below on battery life.

image

Energy Dashboard Result

Accurate gas usage per hour!

Note on Battery Life

One minor issue of this module is that battery life is not so great, which is because of the leds for power and pulse. So whilst I said that this is a no soldering project, I would recommend removing the leds from the board once you have everything setup and working (or change the batteries every month or so!)

I hope this helps someone else find an easy to make dumb gas meter usage monitoring setup. Please feel free to ask any questions if you need help.

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UPDATE: Battery Life Issues
Well I am finding that, even with the leds removed, battery life was still very poor. After some research, I discovered that the SS49E hall sensor (like many hall sensors) uses about 5ma constantly and the whole board is using about 6ma. Removing the leds does make some difference but the hall sensor is the main power drain. Doing the maths:

6ma x 24 hours = 144mah per day

Standard AA battery = 2500mah

Therefore batteries will last 2500/144 = 17 days

This is rough maths and in reality it lasted about 20 days and the Frient itself also uses some power. But in any case, my point is that this is terrible.

So, I found an answer to this replacing the SS49E with a DRV5032FB (from DigiKey) which is a very low power switch hall sensor which uses a max of 1.8uA, which makes the total board use just under 1ma. So the new maths is like this.

1ma x 24 hours = 24mah per day
2500mah/24 = 104 days (approx 3 months).

Significantly better but still not as good as I would like. Next step is to try and get this hall sensor working in the original sensor board without the comparator chip on the sensor board I am currently using to reduce the current consumption by another mA.

Will let you know how this goes but maybe need to change the title of this to …

Simple, no soldering or programming gas meter interface as long as you use a power supply (which the Frient has a socket for btw!) or a bit of soldering if you want to use batteries

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Did you buy the Frient in US? Looks like it’s only available in Europe.

Bought in the UK.