HVAC vs FastXY
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
HVAC
This app provides quick and easy calculations for HVAC professionals and enthusiasts. It simplifies complex formulas for energy use, airflow, and duct dimensions, making them accessible on your iPhone or iPad.
- SFP calculations
- Heat recovery efficiency
- Air velocity in ducts
- Duct dimensioning
- Pressure drop calculations
- Equivalent diameters
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HVAC Calculator is an app that performs many calculations that are useful to have available for anyone working with or have interest in HVAC and energy use in buildings. The app performs many of the calculations that you never remember the formulas for when you need them for quick calculations, for example in a meeting or out on the construction site. Many of the calculations can also be a bit difficult to calculate with a normal calculator. Now you can perform these calculations easily on your iPhone/iPad. The app is universal, so you only have to buy it once to use it on both iPhone and iPad. The app helps you calculate all this and more: -SFP from measured/design fan power and airflow -SFP at reduced airflow for VAV ventilation -SFP at design conditions or maximum performance for VAV ventilation -Temperature efficiency of heat recovery -Temperature after heat recovery unit (HRU) in air handling unit (AHU) -Temperature of exhaust air from air handling unit after heat recovery -Actual temperature efficiency of heat recovery when the exhaust temperature is limited to minimum 5°C for reuse as frost free garage ventilation -Air velocity in ducts with known dimensions and airflow -Maximum airflow in a duct with dimensions and maximum air velocity as specified requirements -Dimensions of rectangular and circular spiral ducts for specified air flow and velocity requirements -Pressure drop in Pa/m for rectangular and circular spiral ducts -Equivalent diameters for rectangular ducts -Hydraulic diameter for rectangular ducts
FastXY
This app enables high-accuracy GNSS data collection for professional surveying and GIS applications. It supports various data types, stake-out functions, and offline use, with multiple export options for seamless integration with other software.
- High-accuracy GNSS data collection
- Point, line, and polygon data capture
- Submeter or centimeter (RTK) accuracy
- Stake-out feature
- Offline data collection
- Multiple export formats (CSV, shp, DXF/DWG)
- Feature/attribute/value pick lists
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FastXY is a high-accuracy GNSS data collection app designed for use with Eos GNSS receivers (www.eos-gnss.com). Collect point, line, polygon data with submeter or centimeter (RTK) survey-grade accuracy or use its stake-out feature to stake points to survey-grade accuracy. After data is collected, upload your data via CSV, shp, DXF/DWG to your favorite GIS/CAD. Key features: -Setup feature/attribute/value pick lists for easy field data entry. Collect ad hoc data in the field without setting up ahead of time. -Stakeout points loaded from DXF/DWG, CSV or shp files. -Collect raw data for post-processing and auto-submit to OPUS from your mobile device (https://www.ngs.noaa.gov/OPUS/) -World-wide 3D base map for visual reference in the field. -Doesn’t require an internet connection.
Screenshots
Verdict
The clearest difference is price: FastXY at Free against HVAC's $4.99. FastXY also leads on rating (5.0 vs 4.0) and update cadence (every 2 months vs every 5 months). On ads, in-app purchases, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
FastXY is free to download; HVAC costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
FastXY holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 1 and 3 respectively.
HVAC ships an update every 5 months, FastXY every 2 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.
| Parameter | HVAC | FastXY |
|---|---|---|
| Price | $4.99 | Free — better |
| Rating | 4.0 (1 ratings) | 5.0 (3 ratings) — better |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 | 3 — better |
| Update frequency | Every 5 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 16.0 | 15.5 — better |
| Further details — not scored | ||
| Size | 14 MB | 114 MB |
| Age rating | 4+ | 4+ |
| Developer | Trond Rossvoll | Discovery Management Group |
Customer experience
HVAC
FastXY
In-app purchases
HVAC
No in-app purchases
FastXY
No in-app purchases








