One 'unit' on old cuft gas meter -cost?

[FurierTransform]

Hi,
I'm trying to work out exactly what our heating is costing us to run each day. I'm having a complete brain block with these old imperial units- can anyone knowledgeable help out?

I have a 30yr old meter that reads in cuft.
It has 4 white digits that I give to energy company, then a single red digit that increments 1-10 that I ignore when giving readings, then a Zero, then a red clock face dial that I can just about see moving with gas on, that goes from 0 to 0.5 to 1.

My reading went from 1050(1) to 1053(4) (bracketed digit is the single red digit - hope that makes sense) in 24hrs & I'm on the price cap.

I think that means I've used 300.3 cuft of gas? But am not sure.

Sorry, I mean i think ive used 330cuft, not 300.3

From your readings taken

1053.4 minus 1050.1 is 3.3 imperial units of gas used
(each whole, white meter imperial unit is actually 100 cu.ft - crazy, I know, but it is.)

converting that figure, 330cu.ft to m3 (multiply by 2.83)
= 9.34 m3

which, very roughly corresponds to ~ 105 kWh using an average calorific vaue for gas

which would cost £11.02 at standard variable cost of 10.5p per kWh for gas

that figure, MzMwcu.ft (don't know where that came from!)

should be

that figure,330 cu.ft

converting that figure, MzMwcu.ft to m3 (multiply by 2.83)

Confused myself! there, but 330 cu.ft does equate to 9.34 m3 and the calculations therafter are correct

Yes, 3.3 (hundreds of ) cubic feet.
Roughly, multiply by 32 to get in kWh, so 105kWh.
At 10.3p/kWh, pus VAT, about £11

For me 5 units calculations are here with imperial conversion calculations

this includes vat and shows the price of gas before and after the cap

I also have an old style imperial (ft3) meter. I worked out that every 1 unit increase (ignoring the red figure which Br Gas never ask for when I submit meter readings) is equivalent to 32.3 kWH of gas. At Br Gas SVR prices, that's approx. £3.50 (inc VAT) every time the meter goes up 1 unit (e.g 4530 to 4531). Plus approx. £0.30 standing charge per day (inc VAT). Hope that helps you OP

Same as mine. I just times the units by 32 to get khw then x 10p

Yes, this is how I do it and it matches what appears on the bill!

As far as reading and calculating costs from gas meters, AFAICT there are 3 kinds :

i) Metric. These are normally marked m3 (metres cubed) and are the easiest to read. You ignore the red numbers and read the rest. The calculation is :

Meter Reading Difference x 11.1 x tariff price (eg £0.10).

ii) Imperial A. I think these are the most common type of imperial meter. These are normally marked ft3 but are actually normally read in 100x ft3. You ignore the red numbers are read the rest. The calculation is :

Meter Reading difference x 32.3 x tariff price.

iii) Imperial B. These are the confusing ones. Although most advice on line tells you to ignore the red numbers to read the meters, on these you must include them. Once the red numbers are included the calculation is the same as Imperial A. There is an example in this forum somewhere of a person who has this meter type.

The question is, how do you know whether you have Imperial A or B and the only obvious way appears to be that if you get it wrong your bill either becomes ridiculously expensive (think thousands instead of hundreds of £s) if you include the numbers when you are not meant to or ridiculously cheap (think £s instead of hundreds of £s) if you omit the numbers and you are supposed to include them.

BTW if you know what a Fourier transform is you should have no issues converting between different unit types.