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    Water HeatersAdvanced

    Install Tankless Water Heater

    Time
    360–600 min
    Steps
    7
    Pre-check
    5 items
    Skill
    Advanced

    Scope

    Mount, plumb, vent, and commission a gas or electric tankless water heater for endless on-demand hot water, with correct gas, water, and venting hookups.

    Safety

    Read before starting

    Permits and code may be required; verify gas/electrical capacity and venting; follow manufacturer precisely.

    Pre-Check

    5 items · complete before you start
    0 / 26 complete

    Steps

    01

    Layout & Mount

    • Mark mounting points at required clearances
    • Install mounting bracket/anchors per manual
    • Hang unit and verify plumb/level
    Code notes
    • Size the unit per ACCA Manual J/S (IRC §M1401.3). Rule-of-thumb sizing is not code-compliant for replacement permits in most AHJs.
    ✅Continue Gate:Mounting secure and clearances met?
    02

    Venting (Gas units)

    • Assemble vent per listed system; observe orientation and slope
    • Terminate with clearances to openings
    • Seal per manufacturer; support vent runs
    ✅Continue Gate:Venting installed to listing and code?
    03

    Water Connections

    • Install isolation valve kit
    • Cold inlet with screen; hot outlet to manifold
    • Install pressure relief and expansion as required
    Code notes
    • TPR discharge piping per IPC §504.6: full-size of valve outlet, single device, gravity flow, no traps/valves/threaded end, terminate 6″ max above floor or waste-receptor flood rim and ≥2× pipe diameter, pressure rating ≥100 psi @ 180°F.
    • Closed systems (PRV, check, or backflow on cold inlet) require a thermal-expansion tank — IPC §607.3 / UPC §608.
    ✅Continue Gate:Isolation/relief in place; no cross-connection?
    04

    Fuel/Electrical

    • Gas: size and connect line; leak-test with detector/soap
    • Electric: land conductors per diagram; verify ground/bond
    • Route condensate to approved drain (condensing)
    Code notes
    • NFPA 54 / 2024 IFGC gas leak test: medium is air, nitrogen, CO₂, or inert gas — never fuel gas or oxygen. Test pressure ≥1.5× working pressure but ≥3 psig; hold ≥10 min. Sediment trap (drip leg) required upstream of each appliance.
    • Electric tankless: NEC 422 dedicated branch circuit; size per nameplate amperage.
    ✅Continue Gate:No leaks; wiring correct; condensate handled?
    05

    Flush & Debris Protection

    • Flush lines prior to startup
    • Install inlet screen/filters
    • Consider scale inhibitor per water hardness
    ✅Continue Gate:Debris cleared; protection installed?
    06

    Commissioning

    • Power ON; run startup routine per manual
    • Set temperature; run multiple fixtures to stabilize
    • Check error codes; verify venting draft and combustion (gas)
    ✅Continue Gate:Stable operation without faults?
    07

    Owner Handover

    • Demonstrate isolation/flush ports usage
    • Review descaling schedule
    • Document serial and installation data

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