HVAC Load Plus vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
HVAC Load Plus
Perform detailed heating and cooling load calculations for buildings in the field using your iPhone. Access a vast weather database and construction data to generate comprehensive reports that can be emailed or exported to spreadsheets.
- Detailed heating and cooling load calculations
- 1000+ city weather database
- Extensive construction type data
- Unlimited project creation and storage
- Comprehensive load breakdown reports
- Emailable HTML reports with spreadsheet attachments
- Company information display on reports
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The HVAC Load+ iPhone app allows you to perform detailed heating and cooling block loads for small commercial and residential buildings out in the field by taking advantage of the simplicity and power of the iPhone. It performs heating and cooling block load calculations based upon industry standard calculation methods. The following is just a small sample of the features included in this app: 1. Includes a 1000+ world-wide city weather database 2. Includes data for 100s of construction types for walls, roofs, floors, doors, windows, skylights, ceilings, and more 3. Allows you to create and store an unlimited number of projects. You can also copy existing projects to new projects for easy reuse of data 4. Allows you to specify an unlimited # of opaque types (ie – doors, walls, roofs, floors, ceilings), window types, and skylight types for each building 5. Allows you to view comprehensive cooling and heating load breakdown reports including breakdown by opaque load, window load, skylight load, infiltration load, ventilation load and internal load contributions 6. Opaque inputs include opaque type, opaque construction number, dimensions, and opening areas 7. Window inputs include window type, internal and external shading type, overhang dimensions, window area, and more.. 8. Skylight inputs include skylight type, dimensions, orientation, and more.. 9. Additional input types include # of people, # of bedrooms, ventilation airflow, and more.. 10. Includes the ability to display a comprehensive HTML report that you can email to yourself or others, and it also includes a spreadsheet attachment that you can open in Excel to further massage data on your desktop 11. Includes ability to input your company information to display on the emailed report 12. Includes ability to display units in either English (IP) or Metric (SI). 13. Equipment location services It also includes 2 bonus modules: 1. The "HVAC Equipment Locator" has the same functionality as our stand-alone Locator app. It allows you to input information about all of your HVAC equipment, upload it to a remote web server (at www.carmelsoft.com/EL), and SAFELY share information about it with other technicians within your company. The equipment's GPS coordinates become its globally unique identifier, allowing you to input and retrieve information about it just by standing next to it. 2. The “HVAC Quick Load” module allows you to quickly perform rule-of-thumb heating and cooling load calcs based upon just inputting the building type, square area, and # of people. Please see the description located under the stand-alone "HVAC Quick Load" app for more details about it. The benefits of using this app are: 1. Great for use out in the field. Quickly size heating and cooling equipment, show the client, then email the results back to your office for further analysis. 2. Show off your advanced on-screen reports to clients convincing them you are using cutting-edge technology 3. Save time by inputting information in the field and then returning to your office to perform more in-depth analysis This app was designed by Carmel Software Corporation, a 20-year old software design firm specializing in engineering analysis software applications geared toward engineers, architects, technicians, and home owners. In fact, our software powers the analysis capabilities of major Autodesk software tools such as Revit (The makers of AutoCAD). We will continue to update this app based upon user feedback. Please email us at info@carmelsoft.com for any comments. We also offer training and tutorial videos at: www.carmelsoft.com/HVACLoadPlus.
RPN
This app simulates a legendary scientific calculator, offering photo-realistic visuals and advanced functions like integration and root finding. It includes built-in programs and extensions for enhanced usability, making it a powerful tool for complex calculations.
- Photo-realistic look-and-feel
- Programmable with 999 steps
- Integration and root solving
- Built-in application programs
- Live register view
- Program library and backup
- Sharing via email, AirDrop, Dropbox
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RPN-34 CE is the first photo-realistic simulation of Hewlett-Packard's popular mid-range scientific calculator HP-34C for the iPhone. Produced from 1979 through 1983, it was the "Basil" member of the third-generation HP calculators known as the "Spice" series. It was the first pocket-calculator ever capable of doing integration and root finding. While the simulator works like the original calculator, a number of carefully designed extensions, along with the tremendously improved speed, make it joy to use even today. RPN-34 CE comes with the programs of HP's "Applications", "Mathematics", "Surveying", "Student Engineering", and "Statistics" application books built-in! Handbooks may be downloaded from CuVee Software's website. Features: • Photo-realistic look-and-feel • Programmable (999 steps), subroutines, 12 labels, 10 flags • 100 registers, "continuous", with full store/recall arithmetic • "Live" register view • Program listing view with intelligent navigation • Program library, easily backed-up via iTunes • Store and retrieve any number of programs • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • 62 programs pre-installed (53 original HP) Calculator functions: • Integration, root solving • Statistics (mean, standard deviation, linear regression, normal distribution) • Factorial of any number (normal and logarithmic) • Trigonometric and hyperbolic functions (degrees, radians, grads) • Polar/rectangular conversions • Inverse, square root, logarithm, exponential, pi • Storage arithmetic (both store and recall) • Statistics (average, standard deviation, y-estimate, linear regression) • Unit and hours conversions • 31 additional functions not found on the HP-34C, like time and sound Details: cuveesoft.ch/rpn34
Screenshots
Verdict
The clearest difference is price: RPN at $1.99 against HVAC Load Plus's $24.99. RPN also leads on rating (5.0 vs 2.8) and review sentiment (100% vs 60%). On ratings volume, ads, monetization model and chart position 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
HVAC Load Plus costs $24.99 and RPN $1.99 up front. HVAC Load Plus sells 1 one-off in-app purchase. RPN asks for nothing beyond the download.
RPN holds the better App Store score, 5.0 against 2.8. Both are backed by a comparable volume of ratings — 5 and 14 respectively. Written reviews point the same way: 60% of HVAC Load Plus's written reviews are positive against 100% of RPN's.
HVAC Load Plus ships an update every 9 months, RPN every 3 months. The most recent releases landed on September 9, 2026 and September 11, 2026 respectively.
| Parameter | HVAC Load Plus | RPN |
|---|---|---|
| Price | $24.99 | $1.99 — better |
| Rating | 2.8 (5 ratings) | 5.0 (14 ratings) — better |
| Positive reviews | 60.0% of reviews | 100.0% of reviews — better |
| Number of ratings | 5 | 14 — better |
| Update frequency | Every 9 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Paid | Paid |
| Best chart rank | #199 — better | #200 |
| Devices | iPhone, iPod | iPhone, iPod |
| Requires iOS | 13.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 18 MB | 16 MB |
| Age rating | 4+ | 4+ |
| Developer | Carmel Software Corporation | CuVee Software |
Customer experience
HVAC Load Plus
RPN
In-app purchases
HVAC Load Plus
- HVAC Equipment Locator$9.99
RPN
No in-app purchases









