Legal · HVAC Calculator & Ductulator (iOS)

Privacy Policy

Last updated: August 25, 2026

1. Summary

HVAC Calculator & Ductulator ("the app") is an offline field calculator for HVAC/R technicians. There are no accounts and no logins. Every calculation, saved job, and PDF report is created and stored on your device only — we cannot see any of it. The only data that leaves your phone is anonymous usage analytics and the purchase information Apple processes when you buy Pro.

2. Who we are

The app is published by Pairmind Limited, 7/F, MW Tower, 111 Bonham Strand, Sheung Wan, Hong Kong. You can reach us at hello@pairmind.dev. Pairmind Limited is the data controller for the limited information described in this policy.

3. Your calculations stay on your phone

All calculators run entirely on your device — the app works in airplane mode. Inputs, results, saved jobs, your name and company on PDF reports, and the reports themselves are stored locally on your device and are never transmitted to us. If you delete the app, that data is deleted with it.

4. What the app does collect

The app collects a small amount of information, none of which is linked to your identity:

  • Usage analytics — anonymous events such as "a duct calculation was run" or "a paywall was shown", together with a random device-scoped identifier, device model, iOS version, and app version. See section 6.
  • Purchase records — when you buy a subscription or the lifetime unlock, Apple and our purchase-management provider process the App Store receipt so your purchase can be validated and restored. See section 5.

5. Purchases

All payments are handled by Apple through the App Store; we never see your payment details. To validate and restore purchases across reinstalls, the app uses RevenueCat, which processes your App Store receipt and a random app-scoped identifier on our behalf. RevenueCat's privacy policy is available at revenuecat.com/privacy.

6. Analytics

We use PostHog to understand how the app is used in aggregate — which calculators people open, whether features work, and where the app can improve. Events are tied to a random identifier generated on your device, not to your name, email, or any account (the app has none). We do not use analytics to track you across other companies' apps or websites, and we do not sell this data. PostHog's privacy policy is available at posthog.com/privacy.

7. Ad attribution

If you installed the app after tapping an Apple Search Ads ad, the app may pass Apple's anonymous attribution token to RevenueCat so we can tell which ads lead to installs. This token comes from Apple's AdServices framework, contains no personal information, and does not identify you.

8. What we never collect

  • No name, email address, or phone number — the app has no accounts.
  • No location data.
  • No contacts, photos, or files.
  • No calculation inputs, results, saved jobs, or PDF reports.
  • No cross-app or cross-site tracking, and no advertising profiles.
  • Nothing is ever sold to anyone.

9. Data retention

Anonymous analytics events are retained only as long as needed to analyze usage trends, after which they are deleted or aggregated. Purchase records are retained for as long as needed to honor your purchase (including restoring it on a new device) and to meet our legal and accounting obligations.

10. Your rights

Depending on where you live, you may have rights to access, correct, or delete personal information, to object to or restrict certain processing, and to withdraw consent. Because the data we hold is not linked to your identity, we may need you to provide the random device identifier from your device to locate it. To exercise any right, email hello@pairmind.dev. We will respond within the timeframe required by applicable law.

11. Children's privacy

The app is a professional reference tool intended for trained technicians. We do not knowingly collect personal information from children under 16.

12. Changes to this policy

We may update this policy from time to time; the "Last updated" date above will change when we do. Material changes will be reflected on this page.

13. Contact

Questions about this policy or your data: hello@pairmind.dev, or by mail to:

Pairmind Limited
7/F, MW Tower, 111 Bonham Strand,
Sheung Wan, Hong Kong