Weil-McLain 550-110-260/02002 Boiler Manual, continued, Natural gas — 5.0 w.c. min/14.0 w.c. max

Boiler Manual

continued

CHART 5 — FLAME light flashing and POWER light on steady

ALSO — Troubleshooting failure to establish main flame

Electrical shock hazard — Wherever you see ▲TURN OFF POWER▲, follow the instructions. Failure to follow instructions could result in severe personal injury, death or substantial property damage.

• Are main manual shutoff valve and boiler gas valve open?

• Is pilot flame visible through inspection port?

No Yes

•▲TURN OFF POWER▲ to boiler at service switch or breaker.

•Open main manual shutoff valve and boiler gas valve (per Lighting instructions in this manual). Wait at least 45 seconds.

•Turn on power at service switch or breaker. Allow boiler to cycle.

	Does FLAME light flash now?
No		Yes

No

•Check the voltage across terminals "C" and "A" of the gas valve (see Table G, page 33).

Is 24 VAC present there?

Yes No

Yes

•Make sure ground wire terminal is securely fastened to control module mounting screw.

•Boiler should be in normal operating sequence.

•Observe operation until thermostat is satisfied and blower has completed its post-purge cycle.

•Verify inlet gas pressure at gas valve:

Natural gas — 5.0" w.c. min/14.0" w.c. max

Propane — 11.0" w.c. min/14.0" w.c. max

Is gas present at gas valve inlet and

within above range?

Yes No

	• Check the voltage across
• If the wiring from the	terminals "B" and "A" (see
control module to gas	Table G, page 33) of the
valve is intact, replace the	gas valve.
control module.	Is 24 VAC present there?
• Retest.
	No	Yes

• Verify inlet gas pressure at gas valve: Natural gas — 5.0" w.c. min/14.0" w.c. max Propane — 11.0" w.c. min/14.0" w.c. max

•▲TURN OFF POWER▲ to boiler at service switch or breaker.

•Remove air inlet box top (see Figure 27, page 54 for location).

•Verify pilot gas line is not kinked, obstructed or damaged and is correctly attached to pilot and gas valve.

•Verify pilot ignition electrode, electrode ceramic and spark lead wire from control are in good condition. Spark gap should be approximately 1/8".

•Correct any above problems, replacing pilot if burner or wiring is damaged.

•Reinstall air box top to operate boiler for retest after any changes or corrections.

•If none of the above corrects problem, then replace the control module, reinstall air box top, and retest.

•Contact gas supplier to correct pressure or gas supply.

•▲TURN OFF POWER▲ to boiler at service switch or breaker.

•Remove air inlet box cover (see Figure 27, page 54 for location).

•Verify pilot burner is securely attached to pilot bracket, bracket is securely attached to cross tie, and there is no corrosion on the parts which would affect the ground path for flame sense.

•Verify that pilot flame rod, flame rod ceramic and lead wire from control module to flame rod are in good condition.

•Correct any above problems, replacing pilot if burner or wiring is damaged.

Is gas present at gas valve inlet and within above range?

No Yes

• ▲TURN OFF POWER▲ to boiler at service switch or breaker.

• Check flame signal — Detach sense lead from igntion control (Figure 25, item 8, page 44).

• Connect negative lead of MICROAMMETER to control sense terminal (Figure 25, item 8, page 44). Connect positive lead of MICROAMMETER to sense wire.

• DISCONNECT red wire connected to terminal "B" (see Table G, page 33) of the gas valve.

• Turn on power to boiler and allow to cycle. As soon as pilot is burning, the MICROAMMETER should read at least 1.0 microamp.

Is flame signal at least 1.0 microamp?

No	Yes
• If none of the previous steps	• If the wiring from the
(including replacing pilot)
	control module to gas
corrects problem, then replace
	valve is intact, replace the
the control module, reinstall air
	control module and retest.
box cover and retest.

Part number 550-110-260/0200 49