Terms of Service

These terms govern your use of HVAC Duct Designer, the mobile application published by Sylvanity B.V., a private limited company based in the Netherlands ("Sylvanity", "we", "us"). By installing or using the app you agree to these terms. If you do not agree to these terms, do not install or use the app.

HVAC Duct Designer is a mobile application that helps HVAC professionals and students perform duct sizing, velocity, and pressure-loss calculations using established engineering correlations (Darcy–Weisbach, Colebrook–White, ASHRAE fitting-loss tables, etc.). The app is offered with a 7-day free trial of the full feature set; after the trial ends, an auto-renewing subscription, "HVAC Pro", is required to continue using the app. The app is distributed through the Apple App Store (iPhone, iPad) and Google Play (Android). The same terms apply on both platforms, supplemented by the relevant platform's standard end-user terms (see Section 14).

HVAC Duct Designer is intended for adults (HVAC technicians, designers, contractors, mechanical engineers, and engineering students). It is not directed at children and is not listed in the App Store Kids Category or Google Play's Families program. You confirm that you are at least 16 years of age (or the age of digital consent in your country, if higher) when you install or use the app.

Subject to these terms, Sylvanity grants you a personal, non-exclusive, non-transferable, revocable licence to install and use HVAC Duct Designer on any compatible device that you own or control, for personal or internal business use. This licence covers professional use of the calculation outputs, subject to the engineering disclaimer in Section 8.

This licence is also subject to the standard end-user terms of the application store from which you obtained the app. For Apple App Store downloads, this means Apple's Licensed Application End User License Agreement. For Google Play downloads, the Google Play Terms of Service apply.

You may not:

• Copy, modify, decompile, or reverse-engineer the app, except to the extent expressly permitted by applicable law (including, where applicable, EU Directive 2009/24/EC).
• Redistribute, sell, sublicense, rent, or lease the app or any part of it, including any subscription entitlement.
• Use the app or any output from it to construct a competing product, dataset, or library.
• Remove or alter any copyright, trademark, or other proprietary notices in the app.
• Use the app in a way that violates applicable law or that harms the device, network, or other users.

HVAC Duct Designer offers a free trial period of seven (7) days, beginning when the app is first launched on a device. During the trial you have access to the full HVAC Pro feature set. If you do not subscribe before the trial ends, the app's calculation features become unavailable until you start an HVAC Pro subscription; your saved projects and calculations remain on the device and are not deleted by the trial ending, and access is restored when you subscribe.

HVAC Pro is sold as an auto-renewing subscription with a monthly or annual term, billed through the Apple App Store or Google Play depending on where you obtained the app. Specifically:

• Price and term for the available subscription periods are shown to you on the in-app subscription screen and on the App Store / Google Play product page before you commit to purchase. Local taxes and currency conversion are applied by Apple or Google.
• Auto-renewal: the subscription renews automatically at the end of each billing period at the then-current price, unless you cancel at least 24 hours before the end of the current period. Renewal is processed by Apple or Google.
• How to cancel: you can cancel at any time from your device's subscription-management screen. On iOS: Settings → [your name] → Subscriptions. On Android: Google Play Store app → Profile → Payments & subscriptions → Subscriptions. Uninstalling the app does not cancel an active subscription.
• What happens after cancellation: your HVAC Pro access continues until the end of the current paid period; afterwards the app's calculation features become unavailable until you re-subscribe. Your saved projects and calculations remain on the device and are not deleted, and access is restored when you re-subscribe.
• Refunds are handled by Apple or Google under their respective refund policies, not by Sylvanity. Sylvanity has no ability to issue refunds for App Store or Google Play purchases.
• Price changes: if we change the subscription price, Apple or Google will notify you in accordance with their platform rules and you will need to confirm the new price before the next renewal can occur. If you do not confirm, the subscription will not renew.
• EU consumer right of withdrawal: EU consumers normally have a 14-day right of withdrawal for digital purchases. By starting to use the HVAC Pro feature set during the free trial or immediately after subscribing, you expressly consent to the immediate performance of the digital service and acknowledge that you lose your right of withdrawal once performance begins, in accordance with Article 16(m) of Directive 2011/83/EU as amended.

The trial is offered only once per device or per Apple ID / Google account, as enforced by the platform. Resetting the trial via debug controls (where available) is for development purposes only and is not a contractual right.

The HVAC Duct Designer app, including its source code, calculation engine, artwork, sounds, branding, copy, and content, is owned by Sylvanity and protected by copyright, trademark, and other intellectual-property laws. The app uses the RevenueCat SDK and platform-provided in-app purchase libraries under their respective licences. Nothing in these terms transfers ownership of any part of the app to you.

HVAC Duct Designer is a calculation aid. The values it produces are estimates based on published engineering correlations and material data, applied to the inputs you provide. The accuracy of any output depends on the accuracy of those inputs and on the appropriateness of the chosen calculation method for your specific situation.

You are solely responsible for verifying the suitability of any calculation output for your project, including against:

• Applicable national and local building, mechanical, fire, and energy codes;
• Applicable industry standards (ASHRAE, SMACNA, EN, ISO, NEN, and any others that govern your project);
• The manufacturer's data sheets for the specific equipment you intend to install;
• Project-specific safety, acoustic, and indoor-air-quality requirements.

The app is not a substitute for the judgement of a qualified mechanical engineer or licensed HVAC professional. Sylvanity is not responsible for any design decision made on the basis of the app's output, nor for any direct or indirect consequences of installing a system designed using the app.

HVAC Duct Designer is provided "as is" and "as available". To the fullest extent permitted by applicable law, Sylvanity makes no warranties, express or implied, regarding the app, including any implied warranty of merchantability, fitness for a particular purpose, accuracy, or non-infringement. We do not warrant that the app will be uninterrupted or error-free, that defects will be corrected, or that the app will be compatible with any future operating-system version.

To the fullest extent permitted by Dutch law and applicable EU consumer-protection law, Sylvanity is not liable for any indirect, incidental, special, consequential, or punitive damages, or for any loss of profit, revenue, data, or goodwill, arising from your use of (or inability to use) the app or from any reliance on its output, even if we have been advised of the possibility of such damages. Sylvanity's total cumulative liability arising from or related to the app, on any theory of liability, is limited to the greater of (a) the total amount you have paid to Apple or Google for HVAC Pro in the twelve months preceding the event giving rise to the claim, or (b) ten euros (€10).

Nothing in these terms limits or excludes any liability that cannot be limited or excluded under applicable law, including liability for gross negligence, intentional misconduct, death or personal injury caused by negligence, or your statutory rights as a consumer.

The app processes only the limited data needed to operate subscriptions; everything else stays on your device. See the Privacy Policy for full details.

Sylvanity may update the app from time to time and may update these terms when the app's behaviour, the subscription model, or applicable law changes. Updated terms will be posted on this page with a new "Last updated" date. Material changes will also be noted in the App Store and Google Play release notes for the relevant version. Continued use of the app after a change takes effect means you accept the updated terms. If you do not accept the updated terms, you should cancel any active subscription and uninstall the app.

You may stop using the app at any time by uninstalling it; if you have an active subscription you should also cancel it from your device's subscription-management screen as described in Section 6. Sylvanity may discontinue the app, or any version of it, at any time. If the app is removed from the App Store or Google Play or is no longer maintained, an existing installed copy will continue to work for as long as the device's operating system supports it; an active subscription will continue to be billed by Apple or Google until you cancel it.

These terms are governed by the laws of the Netherlands, without regard to conflict-of-law principles. Any dispute arising from these terms or your use of the app will be brought before the competent courts of the Netherlands. This is without prejudice to any mandatory rights you have as a consumer under the laws of your country of residence, including the right to bring proceedings in the courts of that country.

The end-user terms of the application store from which you obtained the app apply in addition to these terms. If there is a conflict between these terms and the application-store terms, the application-store terms prevail to the extent of the conflict and only with respect to the matters they cover (for example, the refund policy and the in-app purchase mechanics).

For users who downloaded the app from the Apple App Store, you acknowledge that these terms are between you and Sylvanity, not Apple. Apple is not responsible for the app, its content, or any failure to conform to any warranty. Apple is, however, a third-party beneficiary of these terms and may enforce them against you.

For users who downloaded the app from Google Play, the Google Play Terms of Service and Google Play's subscription rules apply to your purchase, and Google is responsible for the billing and refund elements of the transaction.

If any provision of these terms is held to be invalid or unenforceable, the remaining provisions remain in full effect. These terms, together with the Privacy Policy and the applicable application-store terms, are the entire agreement between you and Sylvanity regarding the app, and replace any prior agreements on the same subject.

Questions about these Terms of Service? Contact us:

Sylvanity B.V.
Treubstraat 21 U314
2288 EH Rijswijk
The Netherlands

KvK: 96488646
BTW: NL867632860B01

Email: info@sylvanity.eu