Furnace Will Not Light


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Old 02-09-09, 07:16 AM
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Furnace Will Not Light

Ancient [1974] GE fuel oil forced hot air furnace. Has begun refusing to light. When thermostat demands heat, burner starts, no flame, burner shuts off automatically after perhaps fifteen seconds. Reset doesn't help.

Local fuel oil service did three things:

(1) Opened fuel line from pump to burner. Turned on burner, saw fuel oil spurt within half second of start. No problem with fuel delivery.

(2) Opened high tension ignition system. Turned on burner, ran screwdriver across high tension springs. Lots of sparks. No problem with ignition.

(3) Removed ignition rods and fuel delivery pipe assembly. Tried to regap ignition points, broke one off. Replaced one ignition rod and point. Regapped. Replaced fuel nozzle.

(4) Replaced fuel oil filter.

(5) Increased fuel pressure by turning screw on fuel pump, opened air shutters to allow more intake air.

Started system. Immediate ignition. No smoke. Good heat. System ran fine rest of day, cycling on and off without problem. Left house for two days, thermostat set to hold 58F.

Returned yesterday, furnace dead. Same problem. Reset restarts furnace but no ignition. Furnace shuts off automatically.

Performed step #1 above. Same result, fuel spurts within half second of starting burner. Reattached fuel line.

Started system. Immediate ignition, though smoky for perhaps ten seconds. Ran fine all afternoon, evening and into the morning. Now at work, with timed thermostat holding 60F until 7PM then will demand 66F.

What might be causing this problem? Thanks.
 
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Old 02-09-09, 12:19 PM
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When was the last time you had the unit cleaned and serviced? He changed the nozzle and fuel filter but not the strainer.....
 
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Old 02-09-09, 06:00 PM
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Unknown. Closed on the home May 2007. No service since that time. Maybe no service for quite a while before that time. But tomorrow [Tuesday], it will be fully serviced.

P.S.: furnace operating perfectly for 30 hours.
 
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Old 02-10-09, 07:45 AM
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If the company has a reasonable service plan I would take it, you really need to have oil fired equipment serviced on an annual basis.
 
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Old 02-16-09, 08:06 AM
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Plugged Fuel Nozzle

Units are too old [1974] for service contract. Just need to get them through this one last winter.

Have pretty strong evidence fuel nozzle is repeatedly clogging, perhaps due to bad fuel. Here's the chronology:

(1) fuel delivery Tuesday, February 3. Tank was down to 1/4 of 330 gallon capacity.

(2) one furnace dies Thursday night, February 5. Would not light.

(3) local service company comes Friday, February 6. Verifies good fuel pump and good ignition. Regaps ignition rods, replaces fuel nozzle and fuel filter. Furnace runs fine and has continued to run fine since then.

(4) same local service company comes Tuesday, February 10. Performs routine service of all three systems, two hot air furnaces and one hot water heater.

(5) second furnace dies Thursday night, February 12. Will not light.

(6) Friday morning, February 13, I verify that second furnace has good fuel pump and ignition. Reconnect everything, furnace starts and makes good heat.

(7) second furnace dies Friday night, February 13. Will not light.

(8) Saturday morning, February 14, remove igniter assembly from furnace. Fuel does not run out of igniter assembly until fuel nozzle is loosened and removed. Gumout fuel tube, replace fuel nozzle with new [0.65] nozzle, reconnect everything, furnace starts and makes good heat, cycles on and off correctly all day long.

Both Saturday night and Sunday night, steps 7 and 8 repeat. Fuel nozzle is plugged so badly that fuel will not run out of tube until nozzle is loosened and removed. While the furnace cycles all day long, at night the timed thermostat drops the building temperature from 66F to 60F and apparently that sustained cooling triggers the fuel nozzle problem.

Sure seems like bad fuel, which hit first furnace on Feburary 5 and second furnace on February 12 through today. But routine service of February 10 should have replaced all filters in all three systems.

Should I replace the second furnace fuel filter again?

Do fuel nozzles have check balls? Can they clog so badly that fuel is held in the tube until nozzle is loosened and removed?
 
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Old 02-16-09, 09:14 AM
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Originally Posted by FrankNatoli
Do fuel nozzles have check balls? Can they clog so badly that fuel is held in the tube until nozzle is loosened and removed?
No check balls. They can clog that bad, but if it's a smaller nozzle, they can still hold fuel in the tube. Can you see
evidence of dirt on the nozzles brass strainer?


(5) Increased fuel pressure by turning screw on fuel pump, opened air shutters to allow more intake air.

I'm hoping the tech used a pressure gauge to set the fuel pressure and test equipment to set the air shutter?
 
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Old 02-16-09, 09:28 AM
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No and no. Tech did not use fuel pressure gauge or other test equipment. Simply opened the hatch to observe the flame. But you may have just hit on the difference between the furnace that is operating and the furnace that isn't. The one that is operating had the fuel pressure boosted and shutters opened. The one that is having trouble operating once it fully cools is unchanged.

No evidence of dirt on brass strainer. Fuel discharge hole has black smearing but that might happen when I remove the igniter assembly from the furnace. I don't have a wrench that will turn the scalloped ring that holds the brass strainer on the nozzle.

Nozzle is 0.65, which I understand is a very small nozzle.
 
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Old 02-16-09, 09:50 AM
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Originally Posted by FrankNatoli
No and no. Tech did not use fuel pressure gauge or other test equipment. Simply opened the hatch to observe the flame. But you may have just hit on the difference between the furnace that is operating and the furnace that isn't. The one that is operating had the fuel pressure boosted and shutters opened. The one that is having trouble operating once it fully cools is unchanged.

No evidence of dirt on brass strainer. Fuel discharge hole has black smearing but that might happen when I remove the igniter assembly from the furnace. I don't have a wrench that will turn the scalloped ring that holds the brass strainer on the nozzle.

Nozzle is 0.65, which I understand is a very small nozzle.
You could very well have a bad load of fuel or some sludge got stirred up when the tank was filled. Having a look at the filter cartridge to see if it's dirty already will give you an idea.

I can't believe the tech bumped up the pressure without using a gauge. If the pressure was proper and he increased it without checking you could have an over fired furnace.

The only way to set the air is to use test equipment. Setting by eye may get it close, but how do you know for sure that it's right.

On older equipment " providing fuel and ignition is right" I have found that too much air can cause the flame not to light and require a #1 to trace of smoke, but I'm not good enough yet to set that by eye
 
 

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