Help with gas pulse processing on emoncms


Sorry to ask yet another question about this topic, but I’m struggling to process the pulses coming through to emoncms into kwh figures and would appreciate some help.

I’ve searched through previous posts, tried fudging it myself and have also tried to follow the instructions here:

I’ve now got it set up as follows:

I’ve applied a scale factor of 111.92 based on data from my bill (each pulse is 0.01m^3 volume of gas x 39.4 calorific value x 1.02264 correction factor / 3.6 kWh then scaled by 1000 to produce Wh instead of kWh)

It looks like there’s something going wrong at the Wh Accumulator stage? Is there something obvious I’m missing?



Can you expand on “something going wrong” with some data or explanation of what is happening and why that’s not what you expected?

Is this an existing feed or a new setup?
Where is the gas_count originating from? Can it be reset to zero?

If you are not getting any value from the whaccumulater, there is an in-built 25kW max limit that you may be getting caught out by, but that’s just a wild guess based on the “feed last value 0.00” in your screenshot.

sorry - I was alluding to the missing data at the Wh Accumulator and the “feed last value 0.00” you correctly pointed out.

It was a new feed but I’d been pushing different bits of data into it while trying to figure things out and the source data is based on a pulsecount from my gas meter.

I think I was hitting the 25kW limit as you guessed because it sprung into life and started showing data when I changed the scaling factor to log as kWh instead… I’ve now got the following on my process list:

I’ve since also realised I’m logging two pulses per rotation and that it’s better to use the pulse increment processor based on one of your old posts here

I’ve only corrected it today, so have kept the old process logging for now too, the numbers seem to look more sensible, but will observe for a bit. The gas_power feed (kWh to Power at line 10) is producing some numbers I don’t understand at the moment though - the graph looks like this:

I guess the best way to visualise it would be to bar chart the data by summing values in a given time period? but I don’t get why the numbers are so high? This is what the source data is doing over the same period:

I’ll have a look at the source code and see if it clarifies things too

The total pulse count to pulse increment process will determine the actual “increment this interval” so you cannot use a whaccumulator on the value passed, you must use a standard accumulator to just sum the latest increment to the existing total.

thanks, I’ve made that change now

Every day is a learning day. The Calorific Value applied to your gas consumption, by your supplier, is not necessarily constant!

I’ve taken a bit of a different tack on this now, currently pushing the “Total pulse count to pulse increment” number to an influxDB instance via MQTT to node-red and on to the database, where I’m logging data from my central heating system.

I’m applying a scale factor on the volume of gas logged over 10min intervals to get values for cost or kWh in Grafana for some nice looking graphs…


Lovely looking graph. One question, which device are you capturing pusles with? emontx/emonpi?? I’m just looking into using an emonth v2’s irq pin off my gas meters rj11 port? Any words of wisdom would be appreciated.

Hi Chris

I’m using an emonpi, also using the pins from the rj45 port, here’s a post describing my setup… Measuring Gas Consumption - #2 by mozster

Happy to answer any questions.