Water Heaters in Mercer Island, Wa

Home | Service Areas | Washington Water Heater Service | Mercer Island, WA

Compliance with Local Codes and Regulations

Safety-First Approach

We prioritize safety, adhering to codes and regulations. Our technicians will walk you through the necessary safety checks before starting work.

Key Codes Enforced in Mercer Island

Mercer Island enforces the 2021 Uniform Plumbing Code (UPC), International Fuel Gas Code (IFGC), and International Residential Code (IRC) with Washington State amendments. These ensure safe, efficient water heater installations. Below are key requirements for residential installations—always consult the Mercer Island Community Planning & Development Department for permits and inspections.

Expansion Tanks

• Required for closed plumbing systems (no expansion tank or similar device) to prevent excessive pressure on the water heater and pipes from thermal expansion.

Approved Location

• Gas water heaters cannot be installed in bedrooms, bathrooms, or small, frequently used spaces (e.g., closets) due to carbon monoxide risks, unless they are direct-vent models or installed in a dedicated mechanical room with self-closing doors and proper combustion air.
• Units must be in conditioned space unless rated at 2.0 UEF or higher efficiency. In garages, elevate ignition sources 18 inches above the floor (or use FVIR-listed units) and protect from vehicle impact with a steel bollard if in traffic paths. Provide 24 inches of access clearance.

Earthquake Straps

• Mandatory seismic bracing in Seismic Design Categories C, D0, D1, and D2 (applicable to Mercer Island): Install two ¾-inch x 22-gauge metal straps—one in the upper third and one in the lower third of the tank height (4 inches minimum above controls). Secure to wall framing with ¼-inch lag screws (4–12 inches from tank edge); use a 2×4 cross brace if studs are misaligned. Plumber’s tape is not acceptable.

Venting

• Gas water heaters require Type B double-wall vent piping with 1-inch clearance to combustibles (6 inches at draft hood), secured with three screws per joint. Vents must terminate with a listed cap or roof assembly and include a roof jack or flashing. Direct-vent models have specific termination clearances; all systems must prevent carbon monoxide buildup per IFGC Chapter 5.

Pressure Regulating Valves

• Install a pressure-reducing valve on the main water supply if system pressure exceeds 80 PSI to protect the heater and plumbing from damage. Additionally, every water heater needs a ¾-inch temperature and pressure relief (T&P) valve, piped to discharge 6–24 inches above grade (or to an approved drain; exterior discharge optional for replacements).

Greasepack Gas Valve Replacement

• Obsolete greasepack (packed) valves are not compliant with the 2021 UPC and must be replaced with ball or lever-handle valves for reliable shutoff and inspection approval.

Pans and Drains

• A drain pan with a connected drain line to an approved location (e.g., exterior or floor drain) is required under all water heaters installed indoors, in attics, or over finished spaces to catch leaks and prevent water damage.

Bonding

• Gas and water piping must be electrically bonded and grounded (using #6 AWG copper wire) to prevent corrosion from stray currents and ensure safety per UPC Section 604.8.

Sediment Traps

• A drip leg (sediment trap) is required upstream of the gas control valve on all gas water heaters to capture debris and moisture, protecting the combustion chamber (6-inch minimum length, teed from the supply line).

Dedicated Water Shutoff

• A dedicated full-port shutoff valve (ball or gate type) must be installed on the cold-water inlet line to the water heater, allowing isolation without shutting off household water.

Pipe Insulation

• Insulate hot and cold water pipes with minimum R-3 insulation in unconditioned spaces (e.g., attics, crawl spaces) to reduce heat loss and meet energy code requirements. Under electric water heaters on concrete floors or in unconditioned areas, use R-10 insulation.