Applicable Systems
Lochinvar Knight Boiler (SMART SYSTEM Control)
Symptoms
The Lochinvar Knight boiler SMART SYSTEM control displays fault message E01, indicating an ignition fault. The boiler has failed to establish a flame after multiple ignition attempts during the trial for ignition period, causing a safety lockout.
Possible Causes
- Gas supply pressure too low for proper ignition
- Ignition transformer or spark electrode failed, producing no spark
- Gas valve not opening during the trial for ignition period
- Burner ports clogged with debris or carbon buildup preventing gas flow to the igniter
- Flame sense electrode dirty or misaligned, unable to detect the established flame
Troubleshooting Steps
- Step 1: Check the gas supply pressure at the gas valve inlet during the ignition cycle
Gas pressure is at the required value (typically 7 in. WC for natural gas) - Step 2: Inspect the spark ignition electrode for proper gap and positioning
Electrode gap is correct (typically 1/8 inch) and positioned over the burner port - Step 3: Verify the ignition transformer is producing spark by listening for the spark sound
Audible spark clicking is heard during the trial for ignition - Step 4: Check the gas valve for voltage during the trial for ignition and verify it opens
Gas valve receives 24VAC and opens during the ignition period - Step 5: Inspect and clean the flame sense electrode if the flame is established but not detected
Flame sense electrode is clean and properly positioned in the flame path
How to Reset
To reset: 1) Fix the gas supply, ignition, or flame sense issue. 2) Press the RESET button on the SMART SYSTEM control. 3) The boiler will attempt a new ignition sequence. Caution: After 3 consecutive E01 faults, the control will enter hard lockout and require a longer cooldown period. Do not repeatedly reset without fixing the cause.
Common Replacement Parts
- 100250: Lochinvar spark ignition electrode (Replace if ceramic is cracked or electrode tip is eroded)
- 100265: Lochinvar flame sense electrode (Clean with emery cloth; replace if heavily corroded)
Frequently Asked Questions
- Q: What happens during the trial for ignition?
The SMART SYSTEM control opens the gas valve for a specific time period (typically 4-7 seconds). During this time, the spark electrode ignites the gas-air mixture, and the flame sense electrode verifies the flame is present. If no flame is detected by the end of the trial, the gas valve closes and E01 is triggered.
- Q: Can I test the flame signal?
Yes. The SMART SYSTEM display shows the flame signal in microamps. During normal firing at high fire, the flame signal should be at least 10 microamps. A signal below 5 microamps indicates a weak flame sense that may cause intermittent E01 faults. Clean or replace the flame sense electrode.
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Source: Lochinvar Knight Boiler Service Manual KB-SER-08, Troubleshooting Table
Category: Boiler
Published: 2026-10-16
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