Trade Exam · Module 4

Water Heaters: Strapping, Relief Valves and Safe Installation

Lesson 2 of 9~20 minFree previewCurrent as of September 2026Leer en español

How the 2025 California Plumbing Code wants a water heater installed: a permit for every install or replacement, earthquake straps in the upper and lower thirds with the lower strap at least 4 inches above the controls, ignition sources 18 inches above a residential garage floor unless the heater is FVIR listed, a watertight pan where a leak would do damage, a relief valve set no higher than 150 psi with full-size discharge piping that ends 6 to 24 inches above the ground, and an expansion tank wherever a check valve, backflow preventer or regulator closes the system.

Key Takeaways

CPC 502.1: installing, removing or replacing a water heater without a permit is unlawful.
CPC 507.2: strap within the upper one-third and lower one-third of the heater's height, with the lower strap at least 4 inches above the controls. Health and Safety Code 19211 requires bracing for new, replacement and existing residential water heaters.
CPC 507.13: in a residential garage, burners, switches and ignition devices are at least 18 inches above the floor unless the heater is a listed flammable vapor ignition resistant (FVIR) appliance.
CPC 507.5: where a leak would cause damage, use a corrosion-resistant pan at least 1-1/2 inches deep with at least a 3/4 inch drain. A relief valve may not discharge into the pan.
CPC 504.4 and 608.4: relief valves are set above the water service pressure and never above 150 psi, with no shutoff valve between the valve and the heater.
CPC 608.5: discharge piping is full size, has no valves, drains by gravity, and ends through an air gap or outdoors 6 to 24 inches above the ground, pointing down, not threaded.
CPC 608.3: a check valve, backflow preventer or other normally closed device requires a listed, adequately sized expansion tank on the building side.
CPC 606.2: a fullway valve goes on the cold water supply at or near each water heater.

Why This Matters

A water heater combines everything the C-36 exam likes: pressure, heat, fuel gas, venting and earthquake safety. Most of the rules live in CPC Chapter 5 (water heaters) and Section 608 (pressure and relief valves). The good news is that the key numbers are few and specific. Learn them exactly as the code states them.

Start with two general rules. CPC 501.1 says water heaters are installed in accordance with the manufacturer's installation instructions, and the final installation is approved by the Authority Having Jurisdiction. CPC 502.1 says it is unlawful to install, remove, or replace a water heater without first getting a permit. A like-for-like swap in a garage still needs a permit.

Location Rules

Bedrooms and bathrooms (504.1): a water heater there must be a direct-vent type, or a fuel-burning heater may sit in a closet in that room if the closet has a listed gasketed door assembly with a listed self-closing device, a threshold and bottom seal, combustion air from outdoors, and is used only for the water heater.
Close to the vent (504.2): heaters other than direct-vent are located as close as practical to the chimney or gas vent.
Clearances (504.3): a listed heater follows its listing and the manufacturer's instructions. An unlisted heater needs approval first and not less than 12 inches of clearance on all sides.
Residential garages (507.13): heating elements, switches, burners and burner-ignition devices are not less than 18 inches above the floor. The exception is a listed flammable vapor ignition resistant (FVIR) appliance. Heaters in garages are also protected from vehicle damage by barriers, elevation, or location out of the vehicle path (507.13.1).
On the ground (507.4): a heater supported from the earth rests on level concrete or another approved base at least 3 inches above the adjoining ground.
Service access (507.25): unless otherwise specified, keep working space of not less than 30 inches in depth, width and height.

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