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OH-HYD practice questions - frequently asked questions

Plain answers about how OH-HYD Exam Prep works: the exam, the questions, pricing, the free trial, and what you actually get.

No - and you should be wary of any site claiming otherwise. Every question here is original, written to mirror the style, difficulty, and judgment the real OH-HYD exam tests. Each one comes with a plain-language explanation of why the right answer is right and the others aren't.

The OH-HYD exam spans 7 domains: General Knowledge (32% of the exam); Heating Equipment (20% of the exam); Piping, Pumps, Valves (20% of the exam); Fuel Gas and Oil (2% of the exam); Venting (10% of the exam); Controls (10% of the exam); Tests and Inspections (6% of the exam). Every practice question on this site is tagged to one of these domains.

The domains are not weighted equally on the exam. By share of the marks: General Knowledge 32%; Heating Equipment 20%; Piping, Pumps, Valves 20%; Venting 10%; Controls 10%; Tests and Inspections 6%; Fuel Gas and Oil 2%.

The OH-HYD exam has 52 questions and is completed in 2 hours 30 minutes. Our timed practice mirrors that length and pacing, so exam day feels familiar.

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