Boiler and Steam Fitting (C-4) · Lesson 4 of 7

Hydronic Test Pressure and Relief Valve Discharge (CMC 1205.2, 1206.2)

"Hydronic Test Pressure and Relief Valve Discharge (CMC 1205.2, 1206.2)" is lesson 4 of 7 in the Boiler and Steam Fitting (C-4) Learning Hub. It opens with "The Pressure Test Rule" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. The Pressure Test Rule
  2. Apply the Larger-Of Rule
  3. Expansion Tank Test Rating Is Different
  4. Relief Valves: Number, Location, Listing
  5. Discharge Piping Rules

The worked example in the course applies this lesson to a realistic job in 5 steps, from "Piping test pressure" through "Check the proposed relief discharge".

What you'll be able to do

  • Explain the main idea of "Hydronic Test Pressure and Relief Valve Discharge (CMC 1205.2, 1206.2)" in plain language you can use on the exam.
  • Apply this step with confidence: "Expansion Tank Test Rating Is Different".
  • Apply this step with confidence: "Relief Valves: Number, Location, Listing".
  • Apply this step with confidence: "Discharge Piping Rules".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Test Pressure and Relief Valve DischargeRELIEF VALVE DISCHARGEBOILER60 psi loopRNo valve,no trap,not threadedGRADE12 in abovegradeAllowed: 6 in to 2 ftPIPING TEST (CMC 1205.2)Test = larger of 1.5 x operating or 100 psi60 psi: 1.5 x 60 = 90, floor governs = 100 psi85 psi: 1.5 x 85 = 127.5 psiHold 30 min, no perceptible dropCLOSED EXPANSION TANK (1004.3)Hydrostatic test design = 2.5 x working2.5 x 60 = 150 psiOver 30 psi: ASME BPVC Section VIII.1Drain tank without emptying the systemRELIEF DISCHARGE CHECKLIST (1206.2, 1005.3)Full size of valve outlet, pointing down; gravity flow through an air gap into drainage, or outsideOutside end 6 in to 2 ft above ground; visible; not into a water heater pan; no isolation of any kindAbove 212 F operating temperature: splash shield or centrifugal separatorTest at 100 psi for 30 min; tank rated 150 psi; discharge ends 12 in above gradeSource: 2025 California Mechanical Code 1205.2, 1004.3, 1209.3, 1206.1, 1206.2, 1005.3CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: The Pressure Test Rule

2025 CMC §1205.2 requires hydronic system piping and components to be tested at not less than one and one-half times the operating pressure, but not less than 100 psi. The test may use water or air, except that plastic pipe may not be tested with air, and the pressure must be held for not less than 30 minutes with no perceptible drop. The tests are made in the presence of the Authority Having Jurisdiction. Two exceptions: PEX, PP-R, PP-RCT, PEX-AL-PEX, PE-RT and PE-AL-PE piping may be air tested where the manufacturer's instructions authorize it and no other law prohibits it, and copper tubing shall be tested at not less than 80 psi.

Step 2: Apply the Larger-Of Rule

Compute 1.5 times the operating pressure and compare it with the 100 psi floor; the larger number is the minimum test pressure. A 60 psi loop gives 1.5 x 60 = 90 psi, so the 100 psi floor governs; an 85 psi loop gives 127.5 psi, so the multiplier governs. Flush the heating and cooling sources, piping and tubing after installation with water or a cleaning solution (§1205.3), and give the owner operating and maintenance information (§1205.1).

The remaining 3 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.

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