Mr Combi's Gas Rate Calculator will help you find gas rates (cubic metres per hour, cubic feet per hour and litres per second) and gross and net heat inputs in MJ/h, kW and BTUs per hour.

The app has the following features:

✔ Built-in let-by/tightness testing timers
✔ Built-in conversion calculator
✔ Built-in guide with full gas rate calculations and let-by/tightness testing procedure
✔ Works on all types of meter
✔ Metric and imperial calculators
✔ Supports natural gas, butane and propane
✔ Save manual calorific values for improved accuracy
✔ Select between a 1 and 2 minute timer for metric meters
✔ Selectable timer alert
✔ Supports ¼ft³, ½ ft³ 1ft³, 2ft³ and 5ft³ imperial test dials
✔ Built-in torch
✔ Email results to any destination or share to other apps such as DropBox and Drive
✔ Timers do not reset when the device is rotated
✔ Timers will continue to run if the home button is pressed (metric alert will function also)

The metric timer can be set to either 1 or 2 minutes. For U6 and G4 meters one minute is sufficient, for E6 meters two minutes is recommended for accuracy. The timer can be set to an audible alert, vibrate, both or neither.

A guide has been built into the app with 6 pages:
• Metric gas rate calculations
• Imperial gas rate calculations
• Heat input calculations
• Let-by test procedure
• Tightness test procedure
• Tightness test permissible pressure drops

An extra Quick Converter calculator is included in the app for simple conversions between gas rates and heat inputs. Simply select the type of gas, enter a value, select the units, press the 'Calculate' button and the calculator will show all gas rates (cubic metres per hour, cubic feet per hour and litres per second) and heat inputs (MJ/h, kW and BTUs per hour) based on the CV.

The Tightness Testing function allows you to quickly select between the let-by and tightness tests and has an easy to use timer. No longer do you need to fiddle about with your phone's timer!

Calorific values can be entered manually (and saved) for more accurate gas rate calculation results. The calorific value of natural gas in the UK varies from about 38.3 to 40.5 MJ per cubic metre; this can mean a difference in the gas rate calculation of more than 5%! With this calculator you can add the CV for your area in the settings page and avoid these inaccuracies. The default values set for butane and propane are both the same as supplied by Calor and BOC.

A torch function is included with this app if your device has an LED flash.

This app requires the CAMERA permission to use the LED flash as a torch.