Android app

Privacy Policy — HVAC 608 Prep

Last updated: October 4, 2026

This privacy policy applies to the HVAC 608 Prep Android app (com.gookkis.hvac608), developed and published by Heri Kiswanto ("we"). It explains what data is processed when you use the app, by whom, and what choices you have.

Quick summary

  • The app does not collect any personal data on our servers. We do not operate a server.
  • There is no account, sign-in, cloud sync or leaderboard.
  • Your answers, scores, exam history and saved questions are stored on your device only. The question bank ships inside the app, so studying never needs a connection.
  • The app shows ads through Google AdMob, which as a third party may collect certain data (see below).
  • An optional one-time purchase, Pro, opens every section and removes the ads. Payment is handled entirely by Google Play; we never see your payment details.
  • Beyond that, there is no analytics SDK, crash reporter, tracker, or other third-party service in the app.

Data we collect

None. We do not request, collect, store, transmit, or sell your personal data — including your name, email address, phone number, contacts, photos, location, or the list of apps installed on your device. The app has no backend, no database, and no usage reporting to us.

Your study progress is not an exception to that. Which questions you answered, whether you got them right, your mock exam scores and the questions you saved are all stored and calculated on the device. No path inside the app sends them to us or to anyone else.

The only network traffic the app makes is for loading ads and, if you choose to buy Pro, for Google Play's own purchase flow. Practice, mock exams, reviews and key facts all work without a connection.

Data stored on your device

To do its job, the app stores a small amount of data locally in your device's internal storage:

  • for each question you have answered: how many times you saw it, how many times you got it right, whether your last answer was right, and when you last saw it;
  • the questions you saved;
  • your last 50 mock exams: the date, how long you took, and the score for each section;
  • your preferences: the exam timer on or off, and light, dark or system theme;
  • a flag recording that you have been through the intro screens;
  • the expiry time of an ad-free break, if you watched a rewarded ad to get one;
  • whether Pro has been purchased, as reported by Google Play, so the app can open the sections and hide ads without asking Play on every start;
  • a simple counter that decides when the app offers to ask for a review.

Mastery percentages are not stored on their own: the app recalculates them from your answers every time a screen opens.

This data:

  • is never sent to us or to anyone else;
  • may be included in your account's Google backup (Android Backup) if app backup is enabled on your device — that backup is managed by Google and accessible only to your account;
  • is removed entirely when you clear the app's data or uninstall the app. Reset progress in the app's Settings clears your answers and exam history straight away.

Third-party advertising (Google AdMob)

The app is free and funded by ads served through Google AdMob, a service of Google LLC. To serve and measure ads, Google as a third-party provider may collect and process data from your device, including:

  • the Advertising ID (AAID) — an advertising identifier you can reset at any time;
  • the IP address and the coarse location derived from it;
  • device information such as model, operating system version, language and mobile carrier;
  • ad interactions such as which ads were shown, viewed or clicked.

That data is collected directly by Google, not by us, and is subject to the Google Privacy Policy. A more detailed explanation is available in How Google uses information from sites or apps that use our services. The ad SDK receives none of your answers, scores or saved questions. No ad is shown during a mock exam.

For users in the European Economic Area, the United Kingdom and Switzerland, the app shows Google's consent form (User Messaging Platform) before any ad loads. Your choice there decides whether Google may serve personalised ads, and you can change it again from the Settings screen inside the app.

The app also offers a rewarded ad: one row in Settings trades a single short ad for 30 minutes without ads. Watching is always your choice — no feature is locked behind it.

The Pro purchase (Google Play Billing)

Pro is a single one-time purchase. It opens every Type I, Type II and Type III question, the mock exams for those sections and the Universal exam, and removes all ads. There is no subscription. The Core section is free in full, and each type section offers a free sample. The purchase is made through Google Play, using the Google Play Billing library that ships inside the app.

  • Google Play handles the payment. We do not receive your card number, billing address or any other payment detail; Google's own privacy policy applies to the transaction.
  • What the app receives from Google Play is whether Pro is owned by the Google account on the device, together with a purchase token issued by Google. The app stores that state locally and never sends it to us — we have no server to send it to.
  • The purchase is tied to your Google account. Installing the app on another device with the same account restores it; the "Restore purchases" button in the app asks Google Play again.

App permissions

Permissions the app requests directly:

  • android.permission.INTERNET — loading ads and talking to Google Play for the Pro purchase.
  • com.google.android.gms.permission.AD_ID — access to the Advertising ID for advertising purposes.

The following permissions are added automatically by the libraries the app uses, and are used only by those libraries:

  • android.permission.ACCESS_NETWORK_STATE — checking that a connection exists before loading an ad.
  • android.permission.WAKE_LOCK and android.permission.FOREGROUND_SERVICE — used by the Google libraries that ship inside the app (the ads SDK and its supporting libraries) for their own background work.
  • android.permission.ACCESS_ADSERVICES_AD_ID, ACCESS_ADSERVICES_ATTRIBUTION, ACCESS_ADSERVICES_TOPICS — the Android Privacy Sandbox advertising APIs on Android 13 and above.
  • com.android.vending.BILLING — the Google Play Billing library, used only for the Pro purchase described above.

The app requests no storage, camera, microphone, location, contacts or notification permission, and no other sensitive permission. It sends no notifications.

Your choices

  • Turning off personalised ads. Open Settings › Google › Ads on your Android device and turn on "Opt out of Ads Personalisation" or delete the Advertising ID. Ads will still appear, but they will no longer be personalised. Users in Europe can also change their ad consent choice from the Settings screen inside the app.
  • Resetting the Advertising ID. From the same menu, you can reset the advertising identifier at any time.
  • Removing ads. Buy Pro once, or watch a rewarded ad for a 30-minute break. Both are optional.
  • Using the app without a connection. Every study feature works fully offline. With no connection, no ads are loaded.
  • Clearing your progress. Settings › Reset progress in the app removes your answers, mastery and exam history. Saved questions stay until you unsave them.
  • Deleting all your data. Since everything is stored locally, clearing the app's data (Settings › Apps › HVAC 608 Prep › Storage › Clear data) or uninstalling the app permanently removes every answer, score and setting. There is no copy left on our side, because we never received it. A Pro purchase is not affected: it belongs to your Google account and can be restored.

Children's privacy

The app is a study aid for HVAC and refrigeration technicians preparing for the EPA Section 608 certification exam, and is not directed at children under 13. We do not knowingly collect personal data from children. If you are a parent or guardian and believe your child has provided personal data to us, please contact us at the address below.

Security

All connections to the ad network and to Google Play use HTTPS. Because the app sends no answers, no scores and no personal data to any server, there is no copy of your data on our side that could leak. Your data lives in the app's private space, isolated from other apps by the Android operating system.

Changes to this policy

This privacy policy may be updated from time to time, for example when a feature or a third-party service changes. The latest version is always published on this page with a new update date.

Contact

Questions about this privacy policy can be sent to admin@gookkis.com.