Furnace Igniting Late-BOOM!


  #1  
Old 12-11-04, 11:03 PM
Mike Selvenis
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Question Furnace Igniting Late-BOOM!

Hi,

I'm a new homeowner and currently heat with an oil furnace-steam radiators. All has been fine until today I noticed something odd when it kicked on.

With my limited knowledge of oil furnaces, I can only compare it to when lighting a grill. You've probably experienced difficulty igniting a grill in the past with those push-button ignitors; the gas is on...you "click" and "click" and it won't light UNTIL POOF! and it lights all the gas that has accumulated and you nearly cinged your eyebrows off. Well, earlier today I heard my burner kick on and there was a delay of about 2 seconds until I heard the thunderous ignition of the flame. there's never a delay. It concerned me, but I soon thought nothing of it, just thought it ignited a vit late.

However, tonight I guess it was even later, and it behaved kind of like the grill. The "pump" that draws the oil ( I assume) started, then a short pause (2-3 seconds) and then BOOM! it "Fired". I can only guess that the oil or oil fumes built up, like the grill, and burned all at once. the little metal flap door even jumped open and "clanked" shut because of the pressure.

Is this a serious problem? WHat should I do? Is it something I can fix/adjust/clean/change myself?

Thanks, Mike

Harrisburg, Pa
 
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Old 12-12-04, 05:56 AM
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There is more than one possible cause and I'm not sure if you can do it yourself. The most common cause is a weak ignition transformer. It does exactly what your grill does, light up after the furlis present. The ignition transformer is the black box right on top of the burner. You can test it yourself with a go-no go test by flipping it back and checking the spark with an insulated screwdriver. Don't spend too much time with the burner running because you will be putting fuel in at the same time. It could also be a nozzle problem or ignition setting problem. If you want more info on the transformer, post back. It generates 10,000 volts like the coil in your car so be careful around it. It should make a spark that is about 3/4" long and blue and noisy. You will need to start the screwdriver touching both posts and pull it away from one while keeping it on the other. If you get a weak yellow spark that is 1/4" long, replace the transformer.

What is the brand of burner you are working on?

Ken
 
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Old 12-12-04, 06:28 AM
Mike Selvenis
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My Burner is a Beckett and the other components on top are Honeywell. I just bought the house in August and have been heating lightly since about mid October.
To my understanding, the furnace (U.S. National) is about 25-30 years old, and the burner is 2yrs. old. Frankly, it looks that new, but I can't find any dates on it.

Would this be a simple service call? Is it a common problem? Do I have anything to worry about? I mean, my house isn't gonna' blow up, right?
I"m new to homeowning and new to oil/steam heat. I am pleased with it so far, however.

ps nice to discuss problems with a local guy!

Thanks, Mike

Harrisburg, Pa
 
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Old 12-12-04, 06:32 AM
Mike Selvenis
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Also, what is the cost of things like a transformer? What "parts" make up the BURNER (i.e. ignition transformer, pump (?), nozzle, etc.)? Can I get these parts at Lowe's? If not, what kind of places specialize in the parts other than my fuel oil company, if any?
 
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Old 12-12-04, 01:14 PM
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I'm local on a national basis but don't call me for service. Ha. The Honeywell box is your safety control. It is connected to the flame sensor (cad cell) and when the cad cell sees light it knows your burner is working OK. You don't have to worry about blowing up the house. If the burner hasn't established a flame in 45 seconds, the safety control will lock it out and it won't start until you press the reset button on top of the control. The ignition transformer sits right next to the safety control and hinges back to expose the high voltage terminals and the access to remove the drawer assembly. (nozzle, electrodes and fuel line. I'm not sure if the home centers carry individual parts but I doubt it. Any good heating supply place will have it. The ignition transformer shouldn't cost more than about $50. Check yours first. Don't just replace it.

Ken
 
  #6  
Old 12-12-04, 07:52 PM
Mike Selvenis
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Ken, thanks for your help. That makes me feel better. The furnace did this only once that i heard it today, but i was gone all afternoon. It does give a pretty good boom when it does ignite, but no big deal. It's firing mostly to keep the chamber temp. up, I guess.

I did notice that it did say it will "lock out" after 45sec. on one of the components. However, after 45 seconds of no ignition, won't there be a surplus of unburned oil in the fire area? What then?

Thanks,
Mike
 
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Old 12-13-04, 08:52 AM
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At a firing rate of 1 gallon/hr (as an example) there is only a tiny amount of oil in the chamber after 45 seconds. Roughly 1.5 ounces. However, only a tiny amount is vaporized at one time. As soon as those tiny droplets contact a solid surface, they are absorbed, or they coat the surface. There is no danger of fire (uncontrolled) or explosion if the oil is not in a vaporized form. So you will get the hard ignition sound after 44 seconds just the same as after 10 seconds but you may get a little smoke at the breech while the other fuel gets vaporized by the heat of the flame and burns off. The new safety controls we use are set for 15 seconds (like the commercial burners always were) and will retry to light the unit if it locks out once. It is a nice feature but still wouldn't solve your problem.

Ken
 
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Old 12-13-04, 12:34 PM
Mike Selvenis
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Thanks, Ken.

I called my oil supplier today and they'll stop by to check it tomorrow. They quoted me $60 for the visit and possibly $50 for a new ignition transformer. he said that it wasn't a big concern, but should be checked and not to worry about it.

Anyway, in reference to the oil build up after misfires, I did smell a bit of oil and a touch of smoke that was burned off like you described above. Again, there was only about a 3-4 second delay when normally there is none.

here's another question: let's say it didn't catch for 44 seconds. How many times would the transformer spark to attempt to start the flame? Every second, rapidly, etc.?
And also, you mentioned 1 gal./hr. Is that an average rate for these burners? That sounds pretty efficient. I only hope to burn that little. My furnace burnes for an hour straight only when in "recovery", a time in which i'm rarely home or awake. Would you recommend a "tune up"? are these possible? if so, what's done?

I'll let you know how it turns out.

Thanks again, Mike
 

Last edited by Mike Selvenis; 12-13-04 at 12:47 PM.
 

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