11 No ignition

What the control is telling you

The burner did not light during the ignition sequence. Possible causes are gas supply, spark, flame sensing, venting or the gas valve and PC Board.

Applies to: SENSEI, SENSEI RX/CX and non-SENSEI tankless

Likely causes

• Gas closed, propane tank empty, air in lines, or inlet pressure out of range
• Wrong gas type, or wrong Parameter 10 (SENSEI) / gas DIP switch (non-SENSEI)
• No spark, wrong electrode gap, or loose/dirty electrode or flame rod
• Carbon or white deposits on the flame rod, or flame rod wires swapped
• Undersized gas piping or faulty two-stage regulator
• Vent problems causing flue gas recirculation, or wrong altitude settings
• Moisture in wiring or gas valve, or faulty gas valve, PC Board or MSA/MSB

Test and repair steps

1. Make sure all gas valves are open, the propane tank has gas and is sized right, and air was purged from the lines. Check the site gas type against the rating plate.
2. Measure inlet pressure with every gas appliance at high fire (on condensing non-SENSEI units, front panel on). The rating plate minimum must be held.
3. SENSEI/RX/CX Parameter 10 must be A = natural gas, B = propane (RX/CX: can only change within 20 min of a power reset). Non-SENSEI: check the gas type DIP switch on the PC Board.
4. Warning: Shut off the gas valve feeding the heater before the spark test.
5. Spark test hold the unplugged igniter wire with insulated pliers 1/4 in. from metal and call for hot water. No spark: check plugs, parts and ignition board voltage (Tech Data Sheet). Electrode gap: 0.138 in. (3.5 mm).
6. Spark voltage during ignition SENSEI conn "D" black pin 21/red pin 12 = 11–13 VDC. RX/CX conn "CN9" black pin 12/white pin 10 = 11–14 VDC.
7. Make sure the electrode and flame rod cannot move by hand. If loose, clean them, check the rod for cracks and refit with a new gasket. Non-SENSEI: match flame rod wires to the bracket letters (Y/R/B).
8. Watch through the view glass. If flame appears and then drops out, suspect flame rectification (deposits, bad connection, damaged rod) or the gas system, PC Board or gas valve. Keep going before replacing parts.
9. Warning: Turn off electrical, gas and water. Pull the igniter/flame rod assemblies, clean off deposits and refit. Have a new gasket ready (replace it if the seal is broken).
10. Non-SENSEI (WARNING VE/VA/VB/VC/KA/RH-180/KCM turn off power, gas and water): clear the manifold orifices and burner chamber, blow fins at 120 psi with glasses/mask, or replace the heat exchanger.
11. If inlet pressure drops under load, check gas line sizing (max drop 0.3 in. W.C. NG / 0.5 in. LP on black iron). Two-stage regulator: 6 ft or more away, static max 10 in. NG / 13.5 in. LP.
12. Check the vent (joints, fittings, terminal clearances, approved materials, equivalent length). Check altitude: SENSEI Parameter 02 (A–D by elevation band). Non-SENSEI: DIP switches and manifold pressure.
13. SENSEI liquid from the condensate drain while idle means a leaking heat exchanger. Non-SENSEI: moisture in the gas valve tube means replace the valve. Check the condensate trap/line (not RH-180).
14. Disconnect power, dry out any wet harness connections and find the cause. Isolate from MSA/MSB. Then check the gas valve (SENSEI: 18–22 Ω or 11–13 VDC; RX/CX: 11–13 VDC), orifice color, burners and conversion parts.

Settings for these units

• RSC supply connection sizes · SENSEI
• RSC water quality limits · SENSEI
• RSC clearances to combustibles · SENSEI
• RSC temperature settings available · SENSEI
• RX supply connection sizes · SENSEI RX/CX
• RX water quality limits · SENSEI RX/CX
• RX water treatment and flushing by hardness · SENSEI RX/CX
• RX clearances to combustibles · SENSEI RX/CX