PE Mechanical HVAC and Refrigeration Exam Prep Free practice test →

Free PE Mechanical HVAC and Refrigeration Practice Questions

10 free, exam-style Professional Engineer Mechanical HVAC and Refrigeration (PE Mechanical HVAC and Refrigeration) practice questions with answers and explanations. No signup required. Work through them below, then take the full free PE Mechanical HVAC and Refrigeration practice test to study every exam domain.

Question 1

An air handling unit mixes 4,000 CFM of outdoor air at 95°F dry-bulb with 6,000 CFM of return air at 75°F dry-bulb. What is the mixed-air dry-bulb temperature?

  1. 85°F under applicable rules
  2. 87°F for this purpose
  3. 83°F as commonly understood
  4. 80°F for this purpose
Show answer & explanation

Correct answer: C - 83°F as commonly understood

Question 2

A 15-hp motor with 88% efficiency drives a supply fan. Both the motor and the fan are located inside the conditioned space. What is the total heat gain to the space from this assembly?

  1. 33,600 Btu/h as ordinarily interpreted
  2. 38,200 Btu/h under standard market practice
  3. 5,200 Btu/h under standard market practice
  4. 43,400 Btu/h when applied properly
Show answer & explanation

Correct answer: D - 43,400 Btu/h when applied properly

Question 3

An air handling unit supplies 8,000 CFM of standard air at sea level. The mixed air entering the cooling coil is at 82°F dry-bulb, and the supply air leaving the coil is at 55°F dry-bulb. No dehumidification occurs. What is the sensible cooling capacity of the coil?

  1. 146,900 Btu/h in the typical case
  2. 233,300 Btu/h in the standard framework
  3. 216,000 Btu/h under applicable rules
  4. 259,200 Btu/h in the standard framework
Show answer & explanation

Correct answer: B - 233,300 Btu/h in the standard framework

Question 4

A centrifugal fan delivers 20,000 CFM at 6.0 in. w.g. total static pressure and requires 25 BHP at 1,200 rpm. If the fan speed is reduced to 900 rpm using a variable frequency drive, what is the new brake horsepower?

  1. 10.5 BHP under accepted convention
  2. 7.9 BHP for this purpose
  3. 14.1 BHP in the typical case
  4. 18.8 BHP under standard market practice
Show answer & explanation

Correct answer: A - 10.5 BHP under accepted convention

Question 5

Hot water enters a counterflow heat exchanger at 200°F and leaves at 140°F. Cold water enters at 80°F and leaves at 120°F. What is the log mean temperature difference (LMTD)?

  1. 56°F in the typical case
  2. 80°F under standard market practice
  3. 69.5°F as commonly understood
  4. 70°F under accepted convention
Show answer & explanation

Correct answer: C - 69.5°F as commonly understood

Question 6

A cooling tower receives condenser water at 95°F and cools it to 85°F. The design outdoor wet-bulb temperature is 78°F. What is the cooling tower approach?

  1. 7°F in the typical case
  2. 10°F in the standard framework
  3. 17°F in the standard framework
  4. 3°F under accepted convention
Show answer & explanation

Correct answer: A - 7°F in the typical case

Question 7

A hot-water heating coil is installed in an air handling unit that serves a hospital in a cold climate. The design engineer must select the failure position of the two-way control valve on loss of control signal. What is the correct fail-safe position?

  1. Normally closed, to prevent energy waste under accepted convention
  2. Fail-in-last-position, to maintain the previous setpoint
  3. Normally closed, to prevent space overheating
  4. Normally open, to prevent coil freezing in the typical case
Show answer & explanation

Correct answer: D - Normally open, to prevent coil freezing in the typical case

Question 8

A vapor-compression refrigeration system operates with the following state points: evaporator outlet enthalpy h₁ = 108 Btu/lb, compressor discharge enthalpy h₂ = 126 Btu/lb, condenser outlet enthalpy h₃ = 48 Btu/lb. The expansion is isenthalpic. What is the coefficient of performance (COP) for cooling?

  1. 2.50 in the standard framework
  2. 3.33 under applicable rules
  3. 4.33 in the standard framework
  4. 5.00 under standard market practice
Show answer & explanation

Correct answer: B - 3.33 under applicable rules

Question 9

Air flows through a supply duct at a velocity of 2,400 fpm under standard conditions. What is the velocity pressure in the duct?

  1. 0.60 in. w.g as ordinarily interpreted
  2. 1.44 in. w.g in the typical case
  3. 0.36 in. w.g under accepted convention
  4. 0.72 in. w.g in this context
Show answer & explanation

Correct answer: C - 0.36 in. w.g under accepted convention

Question 10

An open-plan office has a floor area of 1,000 ft² and a design occupancy of 10 people. Using the ASHRAE 62.1 Ventilation Rate Procedure with Rp = 5 CFM/person and Ra = 0.06 CFM/ft², what is the breathing-zone outdoor airflow rate (Vbz)?

  1. 50 CFM in the typical case
  2. 60 CFM in the typical case
  3. 150 CFM for this purpose
  4. 110 CFM in the standard framework
Show answer & explanation

Correct answer: D - 110 CFM in the standard framework

Ready for the real thing?

Practice hundreds more PE Mechanical HVAC and Refrigeration questions with instant scoring, weak-area drills, and full exam simulations.

Start the free practice test See pricing