Below are Gas Rate Calculators for Imperial and Metric with Fuel Type of Natural Gas.

Additional notes: In ‘Imperial’ mode, you may currently have timing for upto 180 seconds using the slider. In ‘Metric’ mode you can adjust the timer between 1 and 120 seconds.

For full instructions on how to carry out the test, see below the calculators.

Heat Input Instructions for an Appliance – Imperial

  1. Ensure that all other gas burning appliances are turned off
  2. Turn on the applinace to be rated to its maximum setting – allow to run for 10 minutes
  3. Time in seconds how long it takes for test dial to complete 1 revolution (1ft3)

  • ft3 x 0.028 = m3

  1. Appliance Input (kW) = (3600/t) x 0.028 x (CV/3.6)
    • t – time in seconds per 1 revolution
    • 0.028 – to convert ft3into m3
    • CV – calorific value of natural gas 38.76MJ/m3 (1040 BTUs)
    • 3.6 – converts Mj into kW
  2. Appliance Input (kW) = (3600/t) x 1040/3412

Heat Input Instructions for an Appliance – Metric

  1. Ensure that all other gas burning appliances are turned off
  2. Turn on the applinace to be rated to its maximum setting – allow to run for 10 minutes
  3. Take the first reading from the meter R1
  4. At exactly 2 minutes take the second reading R2
  • Appliance Input (kW) = Gas Rate ((R2-R1) x 30min) x CV(kW)
    • R1 – first reading of the meter
    • R2 – second reading after 2min
    • CV – calorific value 10.77 kW

If you would like access to a full gas rating chart for metric gas meters upto 0.200 units then please go to Gas Rating Chart Metric

If you would like access to a full gas rating chart for imperial gas meters upto 200 seconds then please go to Gas Rating Chart Imperial

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