Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
The HVAC Toolkit app for the iPhone and iPad is the essential app for anyone in the HVAC industry
$23.99 · In-app purchases
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for HVAC Toolkit: map the core Productivity workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Assumption to check: Limited functionality for users who need advanced calculations.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: High price point may deter casual users.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: User interface can feel cluttered with too many options.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Lack of cloud sync for user data and favorites.
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
The HVAC Toolkit app for the iPhone and iPad is the essential app for anyone in the HVAC industry. It includes a combination of many of our stand-alone iOS applications. Individually, the apps cost a total of $70. By purchasing the Toolkit, you pay only $24: 1. HVAC Equipment Locator 2. HVAC PT Chart 3. HVAC Refrigerant Charge 4. HVAC Duct Sizer 5. HVAC Quick Load 6. Psychrometrics 7. Steam Tables 8. Pipe Sizer - Liquid 9. Pipe Sizer - Steam 10. Pipe Sizer - Gas High 11. Pipe Sizer - Gas Low This is a universal app that works on both the iPhone and iPad. The "HVAC Equipment Locator" module allows you to track, share, and customize your equipment nameplate and maintenance data. The version here includes the ability to customize your input screens. The "HVAC PT Chart" module allows you to easily view the pressure-temperature properties of 75 refrigerants. Think of this app as a digital version of the paper PT charts that you may have carried around with you in the past. The "HVAC Refrigerant Charge" module allows you to perform superheat and subcool refrigerant charge calculations on-the-fly. This app includes pressure-temperature data for over 75 common refrigerants. The "HVAC Duct Sizer" module allows you to quickly size one HVAC duct run and a range of duct sizes. You can specify the total airflow in CFM (or L/s), the aspect ratio and one of either the velocity of air or the friction loss per 100 feet (30 meters). The "HVAC Quick Load" module allows you to perform quick and simple HVAC cooling and heating load calculation analysis. You can specify the building type, total area, and # of people. The results include the total cooling and heating loads and airflows. The "Psychrometrics" module allows you to easily perform single-state and mixed-air HVAC psychrometric calculations for a wide range of barometric air pressures. The "Steam Tables" module allows you to calculate the properties of saturated or superheated steam by specifying 2 input properties. The "HVAC Pipe Sizer - Liquid" module allows you to size a pipe run with many different types of liquids (or fluids), pipe material and fitting types. The "HVAC Pipe Sizer - Steam" module allows you to size a steam pipe run, and it also includes a bonus steam table calculator. The "HVAC Pipe Sizer - Gas High/Low" module allows you to quickly size a simple low (less than or equal to 1.5 psi) and high (greater than 1.5 psi) pressure gas piping system by inputting a number of piping and gas properties. This application includes all of the great features of the individual HVAC iOS applications such as the use of slider controls that allow you to quickly increment or decrement the input values and immediately observe the calculated results. It also allows you to specify different types of liquids, gases, pipe material types, fitting quantities, min and max ranges, and step values. All of the above modules display units in English or Metric. Also, all of the above modules allow you to send emails with inputs and results. The "HVAC Toolkit" application was designed by Carmel Software Corporation, a leader in HVAC design software since 1995. In fact, Autodesk (the makers of AutoCAD) acquired our load calculation software and incorporated it into their leading 3D modeling software called Revit. In addition, Carmel has developed customized apps for organizations such as ASHRAE, Mitsubishi Electric, and Pacific Gas and Electric, amongst others. We also offer all of the above modules as individual apps for the iPhone/iPad: 1. HVAC ResLoad-J 2. HVAC Psych HD 3. HVAC Duct Sizer 4. HVAC Pipe Sizers 5. Steam Tables 6. Psychrometric Plus 7. Psychrometric LT 8. HVAC Pipe Sizer Plus 9. HVAC Pipe Sizer Gas Plus 10. HVAC Quick Load 11. HVAC Load Plus 12. HVAC Residential Load Calcs 13. HVAC Toolkit Ultimate 14. HVAC ASHRAE 62.1 15. HVAC ResVent 62.2 16. HVAC ASHRAE DFDB 17. HVAC ASHRAE Psych Chart
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Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.