# Stationary Engineer Prep — Boilers, chillers, code > Boilers, chillers, code (iPhone/iPad app by 德武 江.) - Source: https://appshunter.io/ios/app/stationary-engineer-prep/id6816498830 (this page in markdown: same URL + `.md`) - Developer: [德武 江](https://appshunter.io/developer/6809179858) - Category: Education, Reference - Price: Free with in-app purchases - Age rating: 4+ - Requires: iOS 15.0 · 8 MB - Languages: American English - Released: 2026-09-30 - Data updated: 2026-10-03 ## What is Stationary Engineer Prep? Practice for stationary engineer and boiler operator licensing with 3,197 questions, every single one carrying a written explanation of why the correct answer is correct and why the others are not. 13 banks, one subscription, covering the whole central plant. BOILER & STEAM - 1,176 questions - Steam Engineer III - 290 - combustion, feedwater, safety valves, turbines - Boiler Operator - 237 - draft, blowdown, refractory, water treatment - Boiler Licensing - 234 - horsepower, inspections, pH, scaling - Controls & Trim - 220 - burners, oxygen trim, water column, economizers - Plant Operation - 195 - drums, deaerators, traps, superheater valves REFRIGERATION & HVAC - 1,512 questions - EPA 608 - 365 - recovery, evacuation, cylinders, the handling rules - Commercial Refrigeration - 249 - walk-ins, cap tubes, oil, valve conversion - HVACR Fundamentals - 239 - air handlers, receivers, filter driers, motor testing - A/C Service - 233 - charge faults, driers, the oil safety switch - Refrigeration Cycle - 221 - superheat, subcooling, metering, diagnostics - Heat Pumps - 205 - reversing valves, defrost, coefficient of performance CODES & BUILDING SYSTEMS - 509 questions - Pressure Vessel Code - 300 - where a relief device goes, what sets the maximum allowable working pressure, why the hydrostatic test is set where it is - Building Systems - 209 - psychrometrics, economizers, zoning, indoor air quality ONE PLANT, ONE APP Boilers and chillers are usually sold as two subjects. They are not two jobs. A stationary engineer runs the fired side, the chilled side, the air handling and the piping that ties them together, and the licence exam asks about all of it in one sitting - so this app does too, and the subscription covers the lot. BUILT FOR WHERE YOU ACTUALLY STUDY Everything is in the app. No account, no sign-in, no server, and no signal required - it works in the boiler room, on the roof, or on a plane. Nothing you do is sent anywhere. HOW IT WORKS - Answer a question and the explanation opens straight away - Practise in order, draw at random, or redo only the ones you got wrong - Mock exams are timed and scored against a 70 per cent pass mark - Read-through lays out every question with its answer and explanation for revision - Progress, accuracy and streaks are tracked per bank - Search across a bank by keyword - Light and dark, three text sizes FREE AND PAID Your first day gives you 25 free questions, and after that it is ten a day. The allowance is shared across all 13 banks, so it is ten questions in the app rather than ten in each. One subscription removes the daily limit and opens mock exams and read-through in every bank - there is no per-bank purchase. ABOUT THE QUESTIONS These are practice questions written for this app. They follow the topics that stationary engineer, boiler operator and refrigerant handling examinations cover, but they are not actual exam questions and they are not an operating procedure. Stationary engineer licensing in the United States is mostly municipal, and eligibility, grade structure and local ordinances are set where you sit the exam, not here. This app is not affiliated with, endorsed by or sponsored by any certifying body, standards organisation, government agency, licensing board, testing organisation or training provider. SUBSCRIPTION TERMS Weekly - $6.99 for 1 week. Monthly - $13.99 for 1 month. Yearly - $79.99 for 1 year. All three unlock the same thing and renew automatically. Payment is charged to your Apple Account at confirmation. The subscription renews unless auto-renew is turned off at least 24 hours before the end of the current period; your account is charged for renewal within 24 hours before the period ends. Manage or cancel any time in Settings - Apple Account - Subscriptions. Terms of Use (EULA): https://jdw159828-glitch.github.io/privacy-policy/terms.html Privacy Policy: https://jdw159828-glitch.github.io/privacy-policy/privacy.html ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Yearly | $79.99 | per year | | Monthly | $13.99 | per month | | Weekly | $6.99 | per 7 days | ## Is Stationary Engineer Prep safe? Not enough ratings yet to assess Stationary Engineer Prep. ## Is Stationary Engineer Prep legit? Stationary Engineer Prep appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for Stationary Engineer Prep is 65 out of 100 points across 7 verification signals from App Store and developer data. ## Version history (last 1 release) ### 1.0 — 2026-09-30 No release notes. ## More apps by 德武 江 - [CNA Prep Lab](https://appshunter.io/ios/app/cna-prep-lab/id6810276833) - [Clipsmith Trim & Compress](https://appshunter.io/ios/app/clipsmith-trim-and-compress/id6811595371) - [Insurance Prep Lab](https://appshunter.io/ios/app/insurance-prep-lab/id6813704930) - [Realty Prep Lab](https://appshunter.io/ios/app/realty-prep-lab/id6813944262) - [Auto Tech Prep](https://appshunter.io/ios/app/auto-tech-prep/id6814610213) - [Water Operator Prep](https://appshunter.io/ios/app/water-operator-prep/id6814912126) All apps by 德武 江: https://appshunter.io/developer/6809179858 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-03.*