Quick Answer: No — tankless water heaters from Rinnai, Rheem (RTGH line), Navien, and Noritz don’t have a standing pilot light at all. They use intermittent electronic ignition (direct spark or a hot-surface igniter) that fires the burner on demand, only when a hot water tap opens, rather than keeping a small flame burning continuously like an older tank-style gas water heater. If your unit won’t produce hot water, the fix isn’t “relighting the pilot” — it’s diagnosing an ignition-system fault, usually flagged by an error code.
If you’ve searched “tankless water heater pilot light won’t stay lit” or similar, you’re applying tank-heater troubleshooting to a unit that was never built that way — worth dropping that assumption before you start taking the front cover off.
Why tankless units don’t need a standing pilot
A standing pilot light exists on older tank water heaters because the heater has to be ready to fire the main burner at any moment, with no fast-acting ignition hardware — so a small flame stays lit around the clock as the ignition source. Tankless units solve the same problem electronically instead: a flow sensor detects the moment a hot water tap opens, a control board opens the gas valve, and a spark igniter or hot-surface igniter lights the main burner directly, all within about a second of flow starting. No flame burns while the unit is idle.
| Standing pilot (older tank heaters) | Tankless ignition (Rinnai, Rheem RTGH, Navien, Noritz) | |
|---|---|---|
| Flame when idle? | Yes — burns continuously | No — gas only flows on active demand |
| Ignition trigger | None needed; pilot is already lit | Flow sensor detects tap opening |
| Ignition method | Small standing gas flame | Direct spark or hot-surface igniter |
| Idle gas use | ~1,000-2,000 BTU/hr continuously | None |
| "Won't light" fix | Relight the pilot by hand | Diagnose the ignition fault/error code |
How ignition actually works on the major brands
Rinnai and Navien both use a direct-spark ignition system: the control board sends power to a spark igniter, the gas valve opens to feed the burner, and a flame rod confirms a stable flame before the igniter shuts off. Rheem’s RTGH gas line and Noritz units follow the same intermittent-ignition principle, using igniter and flame-sensing hardware rather than a continuous pilot. None of these four brands — the ones that make up the large majority of gas tankless units sold in the U.S. — build a standing pilot into a current model.
This is also why tankless units post better UEF efficiency numbers than old standing-pilot tank heaters: eliminating a 24/7 pilot flame removes a genuine, if modest, source of constant gas consumption that has nothing to do with how much hot water anyone actually uses.
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What to check if your unit won’t ignite
Since there’s no pilot to relight, a “no hot water, unit won’t start” problem on a gas tankless unit usually comes down to one of these:
- Ignition failure code — most units display a specific lockout code (e.g., Rinnai’s code 11) rather than just failing silently; check that code first.
- Dirty or misaligned flame sensor — a flame rod that can’t confirm ignition will shut the gas valve back off within seconds, even if the igniter sparked correctly.
- Low gas pressure or a partially closed gas valve — the igniter can spark fine while the burner still doesn’t get enough fuel to sustain a flame.
- Blocked intake or exhaust venting — safety interlocks on sealed-combustion units will prevent ignition if airflow is restricted.
- Failed igniter itself — a worn spark igniter or hot-surface igniter eventually stops producing a reliable spark and needs replacement.
Our error codes guide breaks down what each manufacturer’s specific ignition-failure code points to before you start swapping parts. If the fault traces back to the igniter itself, our igniter replacement guide covers the exact OEM part numbers by brand.
The bottom line
There’s no pilot light to find, relight, or blow out on a modern gas tankless water heater — Rinnai, Rheem’s RTGH line, Navien, and Noritz all use on-demand electronic ignition instead, and electric tankless/mini-tank units don’t use gas at all. If your unit isn’t producing hot water, skip the pilot-relighting instinct and check the error code or diagnostic display instead; that’s where the real fault will show up. See our troubleshooting guide for a fuller diagnostic path.