Easy Gas Engineer

Build 2026-08-12

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Gas Rate & Heat Input Calculator

Easy Gas Engineer — Build 2026-08-12

Smart Meters Help Guide References
AGas Rate Calculator▾
Determines calorific value used in calculations
MJ/m³ — editable if local CV is known
Default CV: Natural Gas = 38.5 MJ/m³. Adjust if your local CV differs — check your gas bill or contact your supplier.
Choose the method that matches your meter type
Record from meter index at start of test
Record from meter index at end of 2 minutes
Method: Record the meter index, start the 2-minute timer, then record again at the end. Gas used = end − start. Gas rate = difference × 30 to convert to m³/h.
⏱ Test Timer
2:00
Tip: The timer auto-sets to 2 minutes for metric, or 1 minute for the alternative method. A sound and vibration alert when complete.
Appliance comparison (optional)

Enter the manufacturer's rated value to check if your measured result is within tolerance.

From the appliance data badge
BSmart Meter Guide (TB 112)▾

Tap a meter to see the gas rating procedure. Based on Gas Safe Technical Bulletin 112.

Landis+Gyr
Landis+Gyr
Libra series
Secure Liberty
Secure Liberty
EG4v 10
Elster
Elster
BK G4E
Flonidan
Flonidan
G4SZV
Itron
Itron
RF1 sV ZB
EDMI G6000
EDMI G6000
Helios
EDMI 60A/60B
EDMI 60A/60B
SMETS2 Ultrasonic

Landis+Gyr — Libra Series (TB 112, Appendix 1)

When inactive the meter display will be blank. See Note 1.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. At the same time as starting a two-minute timer, press button 'A' on the meter to wake up the display. 'Please Wait' is displayed on the screen (there will be a delay on the screen display, but the reading is taken from the time of the first press of button 'A'). See Note 2.
  3. Make a note of the initial meter index reading when displayed.
  4. After a short delay the meter display will go blank.
  5. At exactly two minutes, press the 'A' button again to reawaken the display and show the final reading in m³ (press the 'A' button the same number of times as before to display the meter index reading).
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.
Note 1: If a screen displays the word 'OFF' either the meter credit has expired or the anti-tamper device has been triggered. If 'OFF' is displayed no gas will flow unless the consumer provides emergency credit, or a tamper is reset by the gas supplier.
Note 2: On some models it will be necessary to press the 'A' button again after the 'Please Wait' screen is displayed. Press the 'A' button one or more times to pass the credit or debit display screen until the meter index is shown in m³.

Secure Meters (UK) — Liberty EG4v 10 (TB 112, Appendix 2)

When inactive the meter display will be blank. If the screen displays 'Low Credit', the meter will alternatively display 'A'- ACCEPT and 'B'- IGNORE. In this case the gas user will need to press button 'A' on the meter to accept emergency credit. If the screen includes the word 'OFF' rather than 'ON', this indicates that the meter has either run out of credit or the anti-tamper device has been triggered.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. At the same time as starting a two-minute timer press button '9' on the meter keypad to wake the display. Then immediately press the '9' button two further times (three times in total). The display will show 'VOLUME TST' for two seconds before displaying the meter index in m³ for a further two seconds. Make a note of the meter index reading. Note: Although there is a delay in the meter reading display, the readings displayed are measured at the time of the first press of the '9' button.
  3. After a short delay the meter display will go blank again.
  4. At exactly two minutes, press the '9' button three more times to wake the display and note the final meter reading in m³.
  5. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.

Elster — BK G4E (TB 112, Appendix 3)

The meter uses a traditional G4 meter base with a smart module in place of the mechanical index. The meter can operate in both credit and prepayment modes.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. Press any of the navigation buttons to wake up the display. The meter updates the reading on the first screen in real-time. Within 30 seconds of pressing the button start the two-minute test period timer.
  3. Make a note of the initial meter reading index at the start of the test.
  4. After a short delay the meter display will go blank.
  5. Within 30 seconds of the end of the two-minute test, press any of the navigation buttons to re-awaken the display. This will show the updated meter index. When the two minutes is complete make a note of the final meter reading.
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.

Flonidan — G4SZV (TB 112, Appendix 4)

The meter is badged as GE, the base is manufactured by Metrix and the smart module by Flonidan.

Valve position: This meter displays a symbol in the top left-hand corner of the display that indicates the valve position. Before commencing with a gas rate, the valve must be in the open position. If the valve is in the closed position, then the customer will either need to add a credit payment or contact their gas supplier for advice.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. Press any of the navigation buttons to wake up the display. The index is updated when one of the three buttons is pressed. The meter will display the reading on the first screen and is updated every ten seconds.
  3. Make a note of the initial meter reading index at the start of the test.
  4. Allow the display to go to sleep. This will happen after approximately 30 seconds.
  5. When the timer reaches two minutes (120 seconds) press any button to wake the display. This will show the updated meter index. Make a note of the final meter reading.
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.

Itron — RF1 sV ZB (TB 112, Appendix 5)

The Itron RF1 Smart meter uses the standard Itron RF1 meter and Itron Smart index.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. Press either of the two buttons on the front of the meter — orange or blue. The meter will wake up and start to show the gas flow reading on screen "A0". If screen "A0" does not display, scroll to it by a short press on the orange button.
  3. Within 30 seconds of waking the meter start the two-minute timer and note the meter reading index at the start of the test.
  4. After 30 seconds the index will go blank.
  5. Within 30 seconds of the end of the two minutes (120 seconds) test, press either of the two buttons (orange or blue) to wake the display. This will show the updated meter index. When the two minutes is up, make a note of the final meter reading.
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.

EDMI G6000 — Helios (TB 112, Appendix 6)

For industry flows use the MUE6 model.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. Press and hold the OK button for 3 seconds to wake the meter.
  3. The display index will show the meter reading in real-time. Within 30 seconds start the two-minute timer test period. Make a note of the initial meter reading index at the start of the test.
  4. After a short delay the meter display will go blank.
  5. Within 30 seconds of the end of the two-minute test period, press the OK button for three seconds to wake the display. When the two minutes is complete make a note of the final meter reading.
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.

EDMI 60A/60B — SMETS2 Ultrasonic (TB 112, Appendix 7)

This meter has an IP rating of 67 which makes it suitable for semi-concealed installations where it is liable to get wet.

Gas rating an appliance

  1. Start by running the appliance under test at full rate.
  2. Press and hold the OK button to wake the meter.
  3. Use the navigation buttons to scroll to the m³ screen. Within 30 seconds start the two-minute test period and make a note of the initial meter reading index at the start of the test.
  4. After a short delay the meter display will return to the default screen.
  5. Within 30 seconds of the end of the two-minute test period, press the OK button for 1 second to wake the display. When the two minutes is complete make a note of the final meter reading.
  6. Calculate the gas rate over the two-minute period by subtracting the initial reading from the final reading and then calculate the hourly gas rate of the appliance using the normal method.
Help Guide Formulas CV Table References
Disclaimer: This tool is provided as a calculation aid for competent Gas Safe registered engineers. It does not replace professional engineering judgement. Users are solely responsible for verifying readings, selecting the correct calorific value, and confirming results against the appliance manufacturer's data. Always allow the appliance to run for at least 10 minutes before testing. To the fullest extent permitted by law, the author accepts no liability for any error, omission, or any direct or indirect loss or damage arising from use of this tool or reliance on its output.
© 2026 Stephen J. Denney (app design and original content). Incorporates material from Gas Installation Technology, 3rd Edition (Burcham, Denney, Treloar), © John Wiley & Sons, Ltd. For use by Gas Safe registered engineers. Not for public distribution.
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Help & Reference Guide