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Key Facts: RSES CMS Commercial Refrigeration Exam

100

Practice Questions

OpenExamPrep

80%

Passing Score

RSES

CM required

Prerequisite

RSES

Specialist

CMS Credential

RSES

8

CMS Specialty Categories

RSES

Multiple choice

Exam Format

RSES

The RSES CMS - Commercial Refrigeration exam is one of the Refrigeration Service Engineers Society's Certificate Member Specialist (CMS) examinations. It is a proctored, multiple-choice exam requiring 80% to pass, and candidates must already hold Certificate Member (CM) status before sitting any specialist exam. Content focuses on commercial refrigeration - high/medium/low-temperature systems and loads, multiplexed parallel compressor racks, refrigerant management and oil-return piping, compressors and condensers, evaporators and defrost methods, EPR and CPR valves, and system charging, superheat/subcooling and troubleshooting. RSES sets the exact question count and exam fee, which varies by member status. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample RSES CMS Commercial Refrigeration Practice Questions

Try these sample questions to review concepts for the RSES CMS Commercial Refrigeration exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In commercial refrigeration, a system is generally classified as 'low-temperature' when the refrigerated box is held at approximately which temperature range?
A.35 F to 45 F
B.28 F to 34 F
C.-10 F to 0 F
D.50 F to 60 F
Explanation: Low-temperature commercial refrigeration covers frozen-food and ice-cream storage with box temperatures near -10 F to 0 F, requiring saturated suction temperatures well below 0 F. Medium-temperature systems hold roughly 28 F to 45 F for fresh meat, produce, and dairy.
2A walk-in cooler holding fresh produce at 35 F uses an evaporator with a 10 F TD. What is the approximate saturated suction (evaporating) temperature?
A.45 F
B.25 F
C.35 F
D.10 F
Explanation: Evaporator TD is the difference between box air temperature and the refrigerant's saturated evaporating temperature. With a 35 F box and a 10 F TD, the coil evaporates at 35 - 10 = 25 F. A 10 F TD is typical for medium-temp coils to maintain higher relative humidity.
3A high evaporator TD (for example 20 F or more) on a cooler coil most directly causes which undesirable effect on the stored product?
A.Excessive humidity and condensation on product
B.Low coil capacity and short cycling
C.Product dehydration from low box humidity
D.Higher suction pressure than design
Explanation: A large TD means a very cold coil relative to the box, which condenses and freezes more moisture out of the air, lowering relative humidity and drying out unpackaged product. Medium-temp coolers for produce use a low TD (8-12 F) to keep humidity high; freezers tolerate higher TDs.
4When sizing a condensing unit, the refrigeration 'product load' refers primarily to the heat removed to:
A.Operate the evaporator fan motors
B.Cool and freeze the product to storage temperature
C.Overcome heat gain through the walls
D.Defrost the evaporator coil
Explanation: Product load is the sensible and (for freezers) latent heat removed to bring incoming product down to and hold it at storage temperature, including pull-down. Total box load also includes transmission (wall) load, infiltration, and internal loads such as fans, lights, and people.
5Most commercial refrigeration condensing units are sized to run for what approximate maximum percentage of a 24-hour day to allow for defrost and load swings?
A.50%
B.100%
C.Up to about 16 to 18 hours (roughly 70%)
D.Less than 4 hours
Explanation: Equipment is commonly sized for an 18-hour (or about 16-hour for low-temp) running time per day so that the unit has reserve capacity and idle time for defrost and to recover from door openings or product loading. Loads are often divided by a running-time factor (e.g., 18/24) to find required hourly capacity.
6A self-contained reach-in refrigerator differs from a remote (split) commercial system in that the self-contained unit:
A.Has the condensing unit mounted on or in the cabinet
B.Always uses a flooded evaporator
C.Cannot use a TXV
D.Requires a separate machine room
Explanation: A self-contained unit packages the compressor, condenser, and evaporator together in or on the cabinet, with no field refrigerant piping. Remote systems locate the condensing unit away from the fixture (rooftop or machine room) and connect with field-run refrigerant lines.
7In a typical supermarket, medium-temperature display cases (meat, dairy, produce) are most commonly served by which arrangement?
A.Individual self-contained condensing units at each case
B.A parallel (multiplexed) compressor rack in a machine room
C.A single residential split system
D.Absorption chillers
Explanation: Supermarkets group many cases of similar temperature onto a parallel compressor rack in a machine room, sharing a common suction manifold and remote condenser. This centralizes maintenance, improves efficiency through staging, and uses a single large charge with distributed evaporators.
8The transmission (wall) load for a walk-in box is calculated primarily from the wall area, the temperature difference across the wall, and the:
A.Refrigerant type
B.Insulation U-factor (or R-value)
C.Compressor displacement
D.Evaporator fan horsepower
Explanation: Transmission load = U x A x TD, where U is the overall heat-transfer coefficient of the panel (reciprocal of R-value), A is the surface area, and TD is the inside-to-outside temperature difference. Better insulation (higher R, lower U) reduces this conductive heat gain.
9An air curtain (air screen) across a walk-in cooler or open display case door primarily reduces which component of the box load?
A.Product load
B.Transmission load
C.Infiltration load
D.Defrost load
Explanation: An air curtain creates a moving air barrier that limits the exchange of warm, humid room air with the cold box, directly reducing the infiltration load from door openings or the open face of a display case. This also reduces coil frosting and humidity gain.
10Which internal load is typically ADDED to a freezer box calculation but is essentially absent in a cooler?
A.Evaporator fan heat
B.Door-heater and frost-control heat
C.Lighting heat
D.Occupant heat
Explanation: Freezers require door frame, gasket, and frost-control (anti-sweat) heaters and electric defrost that add heat the system must later remove, a load largely absent in above-freezing coolers. Fan, lighting, and occupant loads apply to both box types.

About the RSES CMS Commercial Refrigeration Exam

The RSES CMS - Commercial Refrigeration exam is a Certificate Member Specialist examination from the Refrigeration Service Engineers Society. It tests advanced commercial refrigeration knowledge - rack/multiplexed systems, refrigerant management and piping, compressors and condensers, evaporators and defrost, EPR/CPR valves, and charging and troubleshooting - and requires a 80% passing score. Candidates must already hold RSES Certificate Member (CM) status.

Exam sponsor: Refrigeration Service Engineers Society (RSES). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Proctored multiple-choice specialist examination requiring 80% to pass; candidates must already hold RSES Certificate Member (CM) status. This practice bank is 100 selected-response items.

Time Limit

Timed and proctored (duration set by RSES)

Passing Score

80%

Exam / Certification Fees

Set by RSES; varies by member status (contact the RSES Educational Branch)

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

18%

Commercial Refrigeration Systems & Loads

Temperature classification, walk-in coolers/freezers, self-contained vs remote, evaporator TD and humidity, product/transmission/infiltration/internal loads, and running-time sizing

17%

Multiplexed / Rack & Parallel Systems

Parallel racks, shared suction/discharge manifolds, compressor staging, satellite compressors, oil management, EPR temperature control, mechanical subcooling, and floating suction/head pressure

17%

Refrigerant Management & Piping

Oil-return velocities, double risers and P-traps, flash gas, filter-driers, R-448A/R-449A blends, zeotropic glide and liquid charging, POE oil, EPA 608, evacuation, and brazing with nitrogen

17%

Compressors & Condensers

Positive-displacement compressors, unloaders and hot-gas bypass, compression ratio, two-stage/cascade, condenser types, heat of rejection, head-pressure control, receivers, and safety controls

17%

Evaporators, Defrost & EPR/CPR Valves

DX evaporators and distributors, TXV/EEV superheat control, EPR (hold-back) and CPR valves, off-cycle/electric/hot-gas/demand defrost, termination and fan delay, drain heaters, and pump-down

14%

System Charging, Superheat/Subcooling & Troubleshooting

Measuring superheat/subcooling, weighing in charge, diagnosing undercharge/overcharge/restrictions, high-head and floodback symptoms, burnout cleanup, leak detection, and case-level fault isolation

Preparing for the RSES CMS Commercial Refrigeration Exam

What You Need to Know

  • Passing score: 80%
  • Assessment: Proctored multiple-choice specialist examination requiring 80% to pass; candidates must already hold RSES Certificate Member (CM) status. This practice bank is 100 selected-response items.
  • Time limit: Timed and proctored (duration set by RSES)
  • Exam / certification fees: Set by RSES; varies by member status (contact the RSES Educational Branch) Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

RSES CMS Commercial Refrigeration: Suggested Study Strategy

1Know the EPR vs CPR distinction cold: an EPR holds an evaporator's pressure up (closes on a drop of inlet pressure); a CPR protects the compressor by limiting suction pressure (closes on a rise of outlet pressure)
2Master oil-return piping rules: roughly 700 fpm minimum in horizontal suction runs and 1,500 fpm in vertical risers, with P-traps at riser bases and double risers for capacity-controlled systems
3Practice TD math: saturated suction temperature equals box temperature minus evaporator TD, and remember low TD keeps humidity high while high TD dries the box
4Understand parallel-rack concepts: shared suction/discharge manifolds, compressor staging on suction pressure, satellite compressors, oil management, and floating suction/head pressure for energy savings
5Study defrost selection: off-cycle for medium-temp only, electric or hot-gas for freezers, plus defrost termination, fan delay, and drain heaters
6Complete all 100 practice questions and review every miss with the AI tutor, focusing on charging by subcooling and on diagnosing undercharge, overcharge, restrictions, and floodback

Frequently Asked Questions

What is the RSES CMS Commercial Refrigeration exam and who administers it?

It is one of the Certificate Member Specialist (CMS) examinations from the Refrigeration Service Engineers Society (RSES). It validates advanced commercial refrigeration expertise and is a multiple-choice exam requiring 80% to pass.

Do I need to pass another exam before the Commercial Refrigeration specialist exam?

Yes. CMS status is earned only after you hold Certificate Member (CM) status, which requires passing the RSES CM HVACR examination first. You must also be an RSES member to sit a specialist exam.

What score do I need to pass the RSES CMS Commercial Refrigeration exam?

You need 80% or better, the standard RSES passing score for the CM exam and the CMS specialist exams. Because the specialty is focused, balanced study across rack systems, piping, defrost, and troubleshooting is essential.

What topics does the Commercial Refrigeration specialty cover?

It covers commercial refrigeration systems and loads, multiplexed/parallel rack systems, refrigerant management and piping, compressors and condensers, evaporators and defrost, EPR/CPR valves, and system charging, superheat/subcooling, and troubleshooting.

How many questions are on the RSES CMS Commercial Refrigeration exam?

RSES sets the exact item count for each specialist exam and does not publish a fixed number publicly; the exams are multiple-choice and graded to a 80% pass mark. This free practice bank provides 100 questions with explanations.

Is this free RSES Commercial Refrigeration practice as good as paid prep?

Our 100 practice questions cover the full commercial refrigeration specialty - rack systems, EPR/CPR, defrost, piping, and charging - with a teaching explanation for every answer plus a free AI tutor. All content is free forever and updated for 2026.