Refrigeration (C-38) · Lesson 7 of 8

Warehouse Evaporators: Specific Efficiency, Fan Control and Static Pressure (Energy Code 120.6(a)3)

"Warehouse Evaporators: Specific Efficiency, Fan Control and Static Pressure (Energy Code 120.6(a)3)" is lesson 7 of 8 in the Refrigeration (C-38) Learning Hub. It opens with "Which Evaporators Section 120.6(a)3 Covers" and works through 5 short steps, then a worked example you can check yourself against.

Open the free trialSee pricing

One-time purchase, no subscription. Law & Business included.

Steps in this lesson

  1. Which Evaporators Section 120.6(a)3 Covers
  2. Fan Motors
  3. Variable Speed and Off-Cycle Airflow
  4. Specific Efficiency: Table 120.6-A-2
  5. Static Pressure and the Quick-Chill Exception

The worked example in the course applies this lesson to a realistic job in 5 steps, moving through "Freezer evaporator input limit", "Cooler evaporator input limit", and "Time at reduced airflow".

What you'll be able to do

  • Explain the main idea of "Warehouse Evaporators: Specific Efficiency, Fan Control and Static Pressure (Energy Code 120.6(a)3)" in plain language you can use on the exam.
  • Apply this step with confidence: "Specific Efficiency: Table 120.6-A-2".
  • Apply this step with confidence: "Static Pressure and the Quick-Chill Exception".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Evaporator Fans: Efficiency and Off-Cycle AirflowFAN CONTROL, NO VARIABLE CAPACITY (3C)Compressor runningDesign airflow 20,000 cfmCompressor off12,000 cfm or lesscut 40% or moreOff-cycle: 16 h per day12 h reduced (75%)4 hReduced airflow for at least 75% of off time.EVAPORATOR EFFICIENCY (120.6-A-2)Max input (W) = Btuh / (Btuh per W)DX halocarbon freezer, 120,000 Btuh120,000 / 40 = 3,000 W maxAmmonia overfeed cooler, 250,000 Btuh250,000 / 50 = 5,000 W maxHalocarbon DX: cooler 45, freezer 40Ammonia or CO2 DX: cooler 35, freezer 25Overfeed: cooler 50, freezer 45Static pressure limit 0.5 in. water (3E)Measured 0.62 in.: FAILFan input 3,000 W and 5,000 W max; off-cycle 12,000 cfmReduce static pressure from 0.62 to 0.5 in. water or less on the freezer evaporatorALSO REQUIRED (120.6(a)3 AND 7)Multi-compressor group or variable capacity: variable-speed fans on temperature or humidity (3B)Quick chill is over 240 Btu/hr-ft² (2 tons per 100 sq ft); fan controls need an acceptance test (7B)Source: 2025 California Energy Code 120.6(a)3, 120.6(a)7, Table 120.6-A-2CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Which Evaporators Section 120.6(a)3 Covers

2025 Energy Code Section 120.6(a)3 applies to new fan-powered evaporators used in coolers and freezers of refrigerated warehouses of 3,000 square feet or more (the Section 120.6(a) scope). Smaller refrigerated spaces follow the Title 20 walk-in rules. The section sets motor, fan-control, efficiency and static-pressure requirements, and the fan controls are verified by an acceptance test before an occupancy permit is granted (Section 120.6(a)7B).

Step 2: Fan Motors

Section 120.6(a)3A requires single-phase evaporator fan motors of less than 1 hp and less than 460 volts, in newly installed evaporators, to be electronically commutated motors or to have a minimum motor efficiency of 70 percent when rated per NEMA Standard MG 1-2006 at full load rating conditions.

Step 3: Variable Speed and Off-Cycle Airflow

Evaporator fans served by a suction group with multiple compressors, or by a single compressor with variable capacity, must be variable speed, controlled by space temperature or humidity (Section 120.6(a)3B). Evaporator fans served by a single compressor without variable capacity must use controls that reduce airflow by at least 40 percent for at least 75 percent of the time the compressor is not running (Section 120.6(a)3C). Exceptions cover alterations of less than all evaporators in an existing space, controlled-atmosphere coolers certified by a licensed engineer for constant 100 percent airflow, and quick-chill areas.

The remaining 2 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

More lessons for this trade

Browse all lesson previews

Ready to practice for real?

Try the real classroom free, no sign-up, or get the full course for your trade.

Open the free trialSee pricing

Independent exam preparation. Contractors Classroom is not affiliated with the Contractors State License Board, and no course can guarantee a passing result.