2 flashes = Thermopile voltage low. Same diagnostic sequence as State and AO Smith Signature 2-flash codes — shared AO Smith gas valve hardware.
What\'s happening
The thermopile (or thermocouple on older models) generates a small voltage from the pilot flame heat. The gas valve\'s safety circuit needs minimum voltage to allow the main burner to fire. Below threshold, the valve closes for safety and flashes 2.
Diagnostic sequence
1. Clean the FVIR intake screen (#1 cause)
FVIR-equipped Reliance units have a fine mesh intake screen at the base of the tank. A clogged screen restricts combustion air, weakens the pilot, drops thermopile voltage. Vacuum from below with a brush attachment. Resolves 40-60% of chronic 2-flash issues.
2. Inspect the pilot flame
Healthy pilot: steady blue flame enveloping the top ⅓ of the thermocouple tip. Problems:
- Weak yellow flame = inadequate gas supply or dirty pilot orifice
- Flame doesn\'t reach thermocouple = pilot orifice or bracket alignment issue
- Flame keeps blowing out = combustion air problem or excessive draft
3. Clean the pilot tube
Spider webs or dust restrict gas flow through the pilot tube. Compressed air to clear (gas off). Reliance manuals call this out as routine maintenance.
4. Replace the thermocouple / thermopile
$15-25 part, 45-minute DIY. Easiest fix if cleaning didn\'t work. See Reliance thermocouple part page.
5. Verify gas pressure
Low incoming pressure prevents proper pilot. Plumber test with manometer at the meter and at the gas valve inlet. Should be 7" WC for natural gas, 11" WC for LP under load.
Reset procedure
- Address the suspected cause first
- Cycle the gas valve: rotate to "Off" → wait 5 min → rotate to "Pilot"
- Press the pilot button and ignite (electronic spark or manual lighter)
- Hold the gas button down for 60 seconds after pilot lights — lets thermocouple heat up fully
- Rotate to "On" and verify LED returns to 1 flash
Bottom line
Most 2-flash cases: clean the intake screen first, then replace the thermocouple. Both are cheap DIY fixes. Persistent 2-flashes after both = gas pressure issue or gas valve.