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PE Mechanical: HVAC and Refrigeration

Psychrometrics and HVAC loads, air and hydronic distribution, refrigeration cycles, and equipment selection.

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Straight from the PE Mechanical: HVAC and Refrigeration bank — 1,400+ questions, every one with a full worked solution.

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A. Sensible & total energy recovery
At a site 5,000 ft5{,}000\,\text{ft} above sea level, a sensible recovery wheel preheats the outdoor air for an office air handler. The wheel handles 4,000 cfm4{,}000\,\text{cfm} of outdoor air entering at 20 °F20\,°\text{F} and an equal 4,000 cfm4{,}000\,\text{cfm} of exhaust air entering at 72 °F72\,°\text{F} (both airflows at site conditions), and its sensible effectiveness at this balanced flow is 70%70\%. The recovered sensible heat rate (Btu/h) is most nearly:
Air-to-air energy recovery: separate supply (OA→SA) and exhaust (RA→EA) airstreams through a recovery wheel4,000 cfm each · ε = 0.7OA 20°FSARA 72°FEA

Figure — drag or pinch to move around

  • 57,400 Btu/h
  • 134,000 Btu/h (correct answer)
  • 160,000 Btu/h
  • 185,000 Btu/h

Worked solution

With balanced flow the maximum sensible transfer uses the span between the two entering streams (§9.2.7, p. 483): t3−t1=72−20=52 °Ft_3-t_1=72-20=52\,°\text{F}. At 5,0005{,}000 ft the standard-air sensible factor is Cs=0.92C_s=0.92 (§9.1.7, p. 454; §9.1.8, p. 456), applied directly to the site airflow, so qs,max=Cs Q (t3−t1)=0.92(4,000)(52)=191,360q_{s,max}=C_s\,Q\,(t_3-t_1)=0.92(4{,}000)(52)=191{,}360 Btu/h and qs=εs qs,max=0.7×191,360=133,952q_s=\varepsilon_s\,q_{s,max}=0.7\times191{,}360=133{,}952 Btu/h. Distractors: used the sea-level sensible factor 1.101.10 at 5,0005{,}000 ft (160,000160{,}000); applied εs\varepsilon_s to the exhaust temperature alone, 0.7×72 °F0.7\times72\,°\text{F}, dropping the outdoor-air temperature from the span (185,000185{,}000); and applied 1−εs=0.31-\varepsilon_s=0.3, the share not recovered (57,40057{,}400).

Difficulty mix

How this bank splits by our own difficulty rating, from quick wins to multi-step problems.

  • Easy18%
  • Medium47%
  • Hard35%

Study handbook

66 concepts — worked theory, key equations, and common pitfalls for every topic.

Sample concept

Moist-Air Properties and the Psychrometric Chart

The six interlocking properties of moist air — dry-bulb, wet-bulb, dew point, humidity ratio, enthalpy, specific volume — and how to fix a state and read processes on the chart.

Almost every HVAC and refrigeration problem on this exam begins by fixing the state of moist air, and almost every wrong answer traces back to a state read incorrectly. Moist air is a two-component mixture — dry air plus a little water vapor — so it takes exactly two independent intensive properties…
W=0.62198 pwp−pwW = 0.62198\,\dfrac{p_w}{p - p_w}
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The PE Mechanical: HVAC and Refrigeration exam at a glance

Sourced from NCEES — the numbers, not the folklore.

Questions
80
scored and pretest, one sitting
Exam time
8h
in a 9h appointment · about 6 min per question
First-time pass rate
74%
55% for repeat takers · NCEES Squared 2025 (FY2024-25)
NCEES fee
$400
per attempt, paid to NCEES; your state board's fees are separate
Retakes
3 per 12 months
at most one attempt per testing window
Reference on screen
NCEES PE Mechanical Reference Handbook
closed book: no notes or references of your own

What NCEES says is on it

Every knowledge area in the official PE Mechanical: HVAC and Refrigeration specification, with the number of questions NCEES says each one gets. The three heaviest are about 89% of the exam. Share is our arithmetic, not an NCEES figure: each range's midpoint as a percentage of all the midpoints.

Knowledge areaQuestionsShare
HVAC Equipment and Components24–3634%
HVAC and Refrigeration Distribution and Systems20–3029%
HVAC Loads and Psychrometrics18–2726%
Supportive Knowledge (HVAC and Refrigeration)8–1211%

Sources: NCEES PE Mechanical: HVAC and Refrigeration exam specification (October 2025) · pass rate: NCEES Squared 2025 (FY2024-25) · fee and retake policy: ncees.org, read 2026-09-15. Your state board sets its own fees and deadlines.

How to prepare for PE Mech — HVAC

Four steps, in the order that pays off — each one built from this exam's own blueprint.

  1. 1

    Study to the blueprint, not the textbook

    HVAC Equipment and Components, HVAC and Refrigeration Distribution and Systems, and HVAC Loads and Psychrometrics are about 89% of the exam. Give them that share of your hours — Supportive Knowledge (HVAC and Refrigeration) is only 8–12 questions.

    See every area's question range
  2. 2

    Practice one area at a time, then mix

    Work a knowledge area until its worked solutions stop surprising you, then switch to mixed sets so recognizing the problem type becomes the skill.

    Practice PE Mech — HVAC questions
  3. 3

    Sit timed mock exams at the real pace

    The real exam gives you about 6 minutes per question. Full-length timed mocks are the only way to find out whether you can hold that pace for 8h.

    Take a mock exam (with a pass)
  4. 4

    Read what the exam actually asks

    A twelve-week plan built on what NCEES publishes: the question range behind each knowledge area, the one on-screen handbook, and six minutes a question.

    How to prepare for the PE Mechanical HVAC exam

Questions, answered

How hard is the PE Mechanical: HVAC and Refrigeration exam?

NCEES reports a 74% pass rate for first-time takers of PE Mechanical: HVAC and Refrigeration and 55% for repeat takers in NCEES Squared 2025 (FY2024-25). It is 80 questions in 8h, about 6 minutes per question, so pacing matters as much as knowledge. The heaviest areas are HVAC Equipment and Components, HVAC and Refrigeration Distribution and Systems, and HVAC Loads and Psychrometrics.

What topics are on the PE Mechanical: HVAC and Refrigeration exam?

NCEES's PE Mechanical: HVAC and Refrigeration specification lists 4 knowledge areas with a question range for each. The heaviest are HVAC Equipment and Components (24–36 questions), HVAC and Refrigeration Distribution and Systems (20–30 questions), and HVAC Loads and Psychrometrics (18–27 questions) — together about 89% of the exam. The full list is in the exam-at-a-glance table on this page.

How long is the PE Mechanical: HVAC and Refrigeration exam?

The PE Mechanical: HVAC and Refrigeration exam is 80 questions in 8h of exam time, inside a 9h appointment that also covers the nondisclosure agreement, the tutorial and a scheduled break. It is a closed-book, computer-based test offered year-round at Pearson VUE test centers.

What reference material do you get on PE Mechanical: HVAC and Refrigeration exam day?

The PE Mechanical: HVAC and Refrigeration exam is closed book. NCEES provides an electronic reference on screen (NCEES PE Mechanical Reference Handbook). No notes, books or references of your own come into the room; you may bring one NCEES-approved calculator, and an on-screen TI-30XS calculator is also available during the exam. Practicing with that same reference in front of you, so you already know where each method lives, is half the preparation.

How much does the PE Mechanical: HVAC and Refrigeration exam cost, and can you retake it?

The NCEES fee for the PE Mechanical: HVAC and Refrigeration exam is $400, paid per attempt when you register through your MyNCEES account; some state licensing boards also charge their own application fee. NCEES allows one attempt per testing window and no more than three attempts in a 12-month period.

What do I get with PE Mechanical: HVAC and Refrigeration on FE → PE Prep?

1,400+ PE Mechanical: HVAC and Refrigeration practice questions, every one with a step-by-step worked solution; unlimited full-length timed mock exams weighted to the NCEES blueprint; a 66-concept study handbook, 600+ flashcards, and an AI tutor. Access is a one-time pass for 1, 3, 6 or 12 months — no subscription, no auto-renew — and the free sample questions need no account. Within 7 days, with little or no paid content used, you can ask for a refund, which we consider under the Refund Policy.

Can you help with the PE experience requirement?

Yes — a built-in PE Experience Tracker helps you record and organize the qualifying engineering experience and references your state board needs for licensure, right alongside your exam prep.

Free reading for PE Mech — HVAC

No account needed — pass rates, worked problems, and what the exam actually asks.

Free PE Mech — HVAC practice problemsReal questions from the bank, with the figures and full worked solutions.Free PE Mech — HVAC formula sheet135 key equations by exam topic, each with what it is for and its handbook reference.How to prepare for the PE Mechanical HVAC examA twelve-week plan built on what NCEES publishes: the question range behind each knowledge area, the one on-screen handbook, and six minutes a question.PE HVAC exam: what the problems actually look likeThree PE HVAC practice problems, fully worked, and why every wrong answer on this exam is an engineered mistake rather than a random number.How hard is the PE Mechanical HVAC exam?One of the friendlier PE depths at 74% first time. Its topic weighting, straight from the NCEES specification: equipment, not psychrometrics, is the biggest block.

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