Burner motor runs, Burner locks out after 4 seconds

There are three factors to operate the gas burner properly:

1.Electricity {(main Power 120V/60 Hz /1 Ph)( secondary 24V)}

2.Gas flow (Incoming pressure should be 10” w.c. with proper gas line without pressure drop during burner operation).

3.Combustion air.

Check these three items properly before proceeding in detail for other problems.

Condition

1. Burner motor runs and:

No flame after pre-purge & no fuel indicator (where	Check 24V feed to airflow switch & after airflow
applicable)	switch to control. Fix or replace the airflow switch.
	If there is no secondary power, then replace the
	24Vtransformer.
No flame, fuel indicator on (where applicable),	Check ignition transformer, electrode, cracked
faulty ignition transformer or spark separately	electrode or gap. Fix or replace.
Fenwal control defective after above tests.	Replace
2. Burner locks out after 4 seconds

	First, check ionization electrode, ionization cable
	(for cracks) and boot. Fix as needed.
Polarity reversed	Check power feed for broken polarity
Bad earth grounding	Fix the ground wire
Gas pressure is too low	Check the gas pressure and adjust to proper pressure
3. Pulsation at start

	First, check the burner head location with respect to
	the end of the flame tube. Adjust as necessary.
Gas pressure is too high.	Use manometer and readjust the pressures.
Blocked Flue	Check draft and clear flue of foreign materials.
4. Pulsation during operation

Burner is not correctly adjusted.	Readjust with combustion analyzer.
The burner is dirty.	Clean the burner.
Defective chimney	Check and change if necessary with liners.
5. Burner locks out

Ionization current is too low.

Check current. Minimum 0.8 micro amps. Check position of ionization electrode and the condition of the cable.

Excess air is too high or too low.	Adjust air shutter.
The gas holes are clogged.	Clean them.
The fresh air intakes are too small.	Check and readjust.
The burner head is out of position.	Check and readjust.

Firing Rate is too low.

Increase the firing rate so that the stack temperature is 350o F or HIGHER. Insulate the chimney.