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.
App Overview
HVAC Quick Load
The HVAC Quick Load is the one and only rule-of-thumb HVAC heating and cooling load application for the iPhone and iPad.
$6.99 · In-app purchases
PRICE
$6.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.3
3 ratings · Below Average
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.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included17 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
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.
Differentiate and validate
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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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for HVAC Quick Load: 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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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
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
Implement more robust validation and helpful error messages.
Assumption to check: Limited user feedback and error handling
Validate with people who use this workflow before building.
Hypothesis 2
Provide options for different HVAC systems and detailed calculations.
Assumption to check: Lack of advanced calculation options
Validate with people who use this workflow before building.
Hypothesis 3
Enhance the UI with more modern design patterns and intuitive navigation.
Assumption to check: Subpar UI design and usability
Validate with people who use this workflow before building.
Hypothesis 4
Add comprehensive help sections and tutorials for users.
Assumption to check: Limited support and help resources
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
The HVAC Quick Load is the one and only rule-of-thumb HVAC heating and cooling load application for the iPhone and iPad. This app now includes the HVAC Equipment Locator. Click here for details: http://bit.ly/1yTq539 This app performs rule-of-thumb HVAC cooling and heating load calculations for many types of commercial, industrial, institutional, and residential buildings. It allows you to quickly calculate the total required cooling and heating loads (in BTU/hr or Tonnage) and air flows (CFM or L/s) by inputting just the building type, total square area and number of people. You can email all of the inputs and results to any email address. In addition, the email includes an Excel spreadsheet attachment from which you can perform more extensive calculations. The basis of the calculations for this utility come from various authoritative HVAC texts that list average cooling and heating load values per square foot for many building types. All values can be displayed in English (IP) and Metric (SI) units. The following is a sample of some of the types of buildings that can be modeled: 1. Cocktail Lounges, Bars, Taverns, Clubhouses 2. Computer Rooms 3. Dining Halls, Lunch Rooms, Cafeterias, Luncheonettes 4. Hospital Patient Rooms, Nursing Home Patient Rooms 5. Jails 6. Kitchens 7. Libraries, Museums 8. Malls, Shopping Centers 9. Medical/Dental Centers, Clinics, and Offices 10. Nightclubs 11. Offices, Commercial 12. ..... and many more This app is great for use out in the field to quickly analyze the cooling and heating properties of a building. However, please note, that it is by no means a substitute for rigorous heating and cooling load calculations, and HVAC equipment and materials should not be selected based upon the results from this application. We also offer the following additional HVAC applications for the iPhone and iPad: 1. HVAC Duct Sizer 2. HVAC Pipe Sizer – Gas Low Pressure 3. HVAC Pipe Sizer - Gas High Pressure 4. HVAC Pipe Sizer – Liquid 5. HVAC Pipe Sizer – Steam 6. Steam Tables 7. Psychrometric Plus 8. Psychrometric LT 9. HVAC Pipe Sizer Plus 10. HVAC Pipe Sizer Gas Plus 11. HVAC Toolkit 12. HVAC Toolkit Ultimate 13. HVAC Residential Load Calcs 14. HVAC Load Plus 15. HVAC Equipment Locator 16. ASHRAE Duct Fitting Database 17. ASHRAE 62.1 Ventilation Load Calcs 18. HVAC Psych HD 19. HVAC ResLoad-J 20. HVAC Residential Load Calcs HD
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Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Supabase
Zustand
React Navigation
TypeScript
BUILD KIT DIFFICULTY
Starter
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.
