Support

Frequently asked

A result disagrees with my ductulator. Which one is right?

Open the working: tap the ƒ(x) mark on the result card (or turn on Show working by default in Settings → Display). You will see the equation, your figures in it, and the source. The most common cause of a difference is air density: a printed ductulator assumes sea-level standard air at 70 °F, and Ductline uses the temperature and elevation you set under Job conditions. Set those to 70 °F and 0 ft and the two will agree to within the reading error of a slide rule. The second most common cause is material: Ductline uses each material's published roughness rather than a galvanised-steel chart with a correction factor.

How do I switch to metric?

Settings → Units → Metric. That changes how numbers are shown and accepted. The fabrication standard (SMACNA or EN) is a separate choice on the same screen, because what your supplier cuts is a different question from how you read numbers — Canadian work, for example, is metric on the drawing and SMACNA in the van.

Where did my projects go?

They are stored on the device, in the app's own folder, and are included in your device backup. They do not sync between devices. If you deleted the app, its projects went with it; restoring the device from a backup taken before the deletion brings them back.

Why is a new project empty?

Deliberately. A new job should not open pre-filled with somebody else's duct and then grade it. Tap Load an example system to see a finished supply-and-return job, or Add supply path to start your own.

What does "critical path" mean on the project screen?

The longest supply path and the longest return path — in total effective length, which is straight duct plus the equivalent length of every fitting. Together they set the design: their pressure drop is what the blower has to overcome, and per ACCA Manual D the design friction rate comes from the available static pressure divided by that combined length. Other paths are shorter, so they are balanced down to the critical ones with dampers; they do not add to the blower's work.

Why does the app say "supply only" and call my friction rate optimistic?

Because Manual D total effective length is the longest supply path plus the longest return path. With no return path entered, the length is too short and the friction rate you can afford looks higher than it really is. Add a return path.

I need to restore my purchase.

There is nothing to restore: Ductline is a one-time purchase with no in-app purchases. Re-download it from the App Store on any device signed in to the same Apple Account, at no charge, from the App Store's Purchased list.

Refunds

Purchases are made through Apple, so refunds are Apple's process: reportaproblem.apple.com. We cannot issue them ourselves.

Does it need a connection?

No. Every calculation runs on the device. The app makes one request to Apple on first launch (see the privacy policy) and none after.

Is this a certified engineering tool?

No. It is a design and verification tool for a competent professional. It does not perform load calculation and does not certify a design for permit. Verify against project documents, equipment data and the governing code.

Reporting a wrong number

This is the report we most want. Send the mode (Find size / Analyse duct / Find airflow), shape, material, application, every input value with its unit, the job conditions (temperature, elevation), the unit system and fabrication standard, and the number you expected with its source. The app is deterministic, so with those we can reproduce your result exactly and either fix it or show you the working.