where do I find the Calorific Value
in Local MQTT
Hi,
the device I am using to display data does not have energy, but it does have volume (for watering plants). I was going to convert daily gas kwh from a SMETS1 meter to volume but I can't see a Calorific Value in my MQTT. Does the meter just assume a CV or not put it on MQTT. An alternative is to timestamp changes and calculate a power and use the electrical power capability to pretend gas is electricity.
thanks
Comments
It's always published on your gas bill for each billing period. I don't think anything gets it to MQTT. I had a look at my Glowmarkt MQTT output and couldn't see calorific value.
I've been looking into this myself, and believe that the meter uses a constant value for the CV, which will not be the same as the monthly average value used by your supplier for billing.
I have found the following page on the National Gas website which provides the CV data for a charging zone over a date period:
https://data.nationalgas.com/find-gas-data
I think downloading the data can probably be automated (I haven't tried yet myself) as the 'URL' button to the far right of 'View data' copies a URL for the request to the clipboard - it seems to include the requested date range and a list of the zones using ID numbers.
And you can find the distribution zone (DZ) for your area using the postcode checker here: https://www.energybrokers.co.uk/gas/gas-network
Hope this helps, although it's probably more information than you were asking for!
Your variable gas calorific value is always on your gas bill. Mine shows as 1.02264 on my last bill. It is NOT part of the Glowmarkt MQTT stream.
Indeed, I was interested in seeing how much the CV varied over the month, rather than just having the average value given on the bill.
And 1.02264 is a correction factor for temperature and pressure - the calorific value is in the range 37.5 to 43.0.
Sorry did I pick the wrong number off my bill.
58.7 × 1.02264 × 39.2† ÷ 3.6 = 653.6
That's for 58.7 units (M^3) consumed.
With 1.02264 volume correction.
And a CV of 39.2
The 3.6 is to convert from Joules.