Free tools for gas engineers

Gas rate calculator

Work out the gas rate and heat input from a test-dial reading. Turn every other appliance off first.

Meter and test dial Time for the test dial, in seconds Calorific value, MJ/m³ (use the figure on the gas bill) Appliance rated input, kW (optional, from the data plate) The rated figure is

Enter the time to see the result.

Gross kW = m³/h × calorific value ÷ 3.6. Net kW = gross ÷ 1.11 for natural gas. This is a calculating aid. Always check the result against the manufacturer's data and follow their instructions and the current regulations.

Internal pipe volume

Add up the internal volume of a gas installation from the pipe sizes and lengths. Useful for tightness and purge calculations.

Meter volume, m³ (optional, from the meter plate or the standard) Other volume, m³ (optional, regulator, appliance, fittings)

Enter a pipe length to see the volume.

Use this volume in the tightness helper

Volume = π ÷ 4 × internal diameter² × length. Sizes are typical internal diameters for copper tube to BS EN 1057 and medium steel tube to BS EN 10255. Check them against the pipe you are using. For polyethylene or flexible pipe choose Custom and enter the internal diameter.

Tightness test helper

Turn a pressure drop into an estimated leak rate. The test period and the permitted pressure drop come from the current standard, so enter the figure from your copy and the helper compares your reading with it.

Installation volume, m³ (from the pipe volume tool above) Pressure at the start, mbar Pressure at the end, mbar Test duration, minutes Permitted pressure drop, mbar (optional, from the standard)

Enter the volume, both pressures and the duration.

Estimated leak = volume × pressure drop ÷ atmospheric pressure (1013 mbar). This is an indication only. It does not replace the tightness test procedure and limits in the current IGEM standard for the installation, and the manufacturer's instructions for the gauge you use. Allow for stabilisation before you start timing.

Water PPM and inhibitor dosing

Estimate the system volume, work out how much inhibitor to add, and top up when a test shows the level has dropped. Use the dose rate and target on the product label.

1. System volume estimate

Number of radiators Average water per radiator, litres (edit to suit) Boiler and cylinder coil, litres 15 mm copper pipework, metres 22 mm copper pipework, metres 28 mm copper pipework, metres

Enter the radiators and pipework.

Radiator and boiler figures are typical averages, so treat the result as an estimate. If you know the real volume, type it into the boxes below instead.

2. How much inhibitor to add

System volume, litres Dose rate, % of the system volume (from the product label)

Enter the system volume.

3. Top up after a test

Concentration found by the test Test result is in Target concentration, % (from the product label)

Enter the system volume above and the test result.

1% by volume = 10,000 ppm. Product to add = system volume × (target − current) ÷ 100, ignoring the small volume the product itself adds. Test kits differ: check what yours reports and the minimum level the manufacturer requires for the warranty.

Boiler manual finder

Pick the manufacturer, type the model and open a search of that manufacturer's own website for the manual. We don't copy manuals: they belong to the manufacturers, and their site always has the latest version.

Manufacturer Model (for example Greenstar 30i) Document

The search opens in a new tab, limited to the manufacturer's own website when you pick one.

Stuck on a fault, not a document? Breakdown AI takes the make, model and fault code and gives you the likely causes, checks and parts. Try it free.

More tools are on the way. Tell us which one would save you the most time: get in touch.

The gas rate calculator is also built into the GASpilot app, free on every plan, with certificates, invoices and reminders.