How do smart gas meters work?

facade

Specifically, how do they measure instantaneous consumption?
As far as I can tell, they use doppler shift to measure gas velocity through a metering tube, but as the battery is good for 10 years, that isn't going to be measured very often;)
(Hot wire is out as there just wouldn't be enough battery power)


So how often are the samples?


Say it samples co-incidentally every time my boiler just happens to be running full chat, only for it to drop back to pilot seconds later for most of the rest of the dead time, won't the readings be astronomically high- and wrong?:(


On the other hand, if my boiler knew when the sample is measured, it could drop to pilot a couple of minutes before each sample, and run full chat the rest of the time........;)

System

Look it another way. I get 15 minute consumption updates from my existing 'old fashioned' digital meter with nothing more than an optical reader that records the number of times that a silver dot in the No 6 goes around in the given period. What makes you think that smart meters are using 'doppler shift' when existing meters are not?

I appreciate that this site is about money saving but your suggestion does sound a bit like one that was going around flight crews many years ago. A flight engineer had worked out that he could watch Pay as You View !!!!!! channels in most hotel bedrooms in America for free by switching away from the selected channel for 10 secs every 1min 50 secs.

facade

It was the best answer I could get from a lot of searching on the interweb.


My proper olden days meter uses the emptying and filling of bellows to measure the actual volume of gas passed through (this means they have to correct for gas temperature in the billing), via nice reliable mechanical linkages and gears.



Smart meters are supposed to use the "better" "more accurate" flow measurement techniques, like ultrasonic doppler shift and hot wire.


Forget the red herring about "winning" by cutting back the gas when it is actually being sampled, as you say, that isn't going to happen.


I'm more concerned about being overcharged if I happen to be using a lot of gas as it is sampled, and then drop back to a much smaller usage for the rest of the time until the next sample.

thorganby

facade wrote: »

I'm more concerned about being overcharged if I happen to be using a lot of gas as it is sampled, and then drop back to a much smaller usage for the rest of the time until the next sample.

You have incorrectly assumed that the volume of gas is not measured very often i.e. a period of several minutes between measurements.

Gas volume is continuously measured and registered in memory, regardless of the flow rate, high or low.

The ultrasonic sensor and associated electronics commonly used in modern meters both smart and the previous generation dumb meters obviously draws very little current.

If your theory was true, how could these meters possibly be certified to meet the required internationally agreed accuracy standards?

The battery life of gas smart meters is extended simply by only transmitting the recorded data every 30 minutes, which is more than enough for all.

facade

thorganby wrote: »

If your theory was true, how could these meters possibly be certified to meet the required internationally agreed accuracy standards?

In house testing?


Test them with constant flow, rather than real world variances?
(Seems to work for car emission and fuel consumption tests )



Be nice to think that they do measure continuously.


I found data on an industrial meter with a 10 year battery, that reckons on 4second samples, which I suppose would be good enough.

System

https://www.ofgem.gov.uk/ofgem-publications/42360/5876-meterapprovalverification-pdf