intermittent issues armstrong sx 80


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Old 12-06-11, 06:37 AM
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intermittent issues armstrong sx 80

This season my furnace has been acting goofy intermittently.
Normal Operation: fans come on, a click or two and everything fires up and works just fine.
Sometimes the fans come on, I will hear extra clicking noises, sometimes a lot in rapid succession, and the furnace kicks on and everything is fine.
Other times, the clicks happen, furnace starts to kick on, then everything shuts off and after a couple minutes, the cycle starts over and sometimes it fires up and works ok, other times it will go through this cycle several times before the furnace comes on.
I recall right at the end of the hot weather (i live in iowa) i heard the clicking noises when i ran the a/c as well. So I am not entirely convinced this is a furnace issue.
I think this is a relay problem, the control board has 2 of them on it, but they are soldered to the board.
Anybody have any experience with this issue? I have read several posts about the clicking stuff but its always "hear some clicks and nothing happens after that" which is not the case with me.
Thanks in advance!!
 
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Old 12-06-11, 07:16 AM
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Probably the circuit board is bad and needs to be replaced.

If you take the cover off the burner compartment of the furnace, you can observe the sequence of events that occur when you turn up the thermostat to turn the furnace on. You need to describe that sequence in more detail when the furnace isn't lighting properly.
 
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Old 12-06-11, 08:21 AM
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Originally Posted by SeattlePioneer
Probably the circuit board is bad and needs to be replaced.

If you take the cover off the burner compartment of the furnace, you can observe the sequence of events that occur when you turn up the thermostat to turn the furnace on. You need to describe that sequence in more detail when the furnace isn't lighting properly.
I will try and do that, it is tricky though since it does not have this problem every time.
 
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Old 12-06-11, 08:56 AM
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Yep. Intermittent problems are the bain of repairmen.


But in this case, that just means cycling the furnace repeatedly until you have a chance to observe these symptoms. Perhaps you need to do that 20-30 times until you can observe that failure often enough to accurately observe what is happening.

I've had occasions where I cycled a furnace a hundred times or more in order to observe intermitent problems.

Frankly, the repairman who hitches up his pants and says, "Well, there's nothing I can do, it's working OK NOW", while he grabs up his fee and walks out the door is a lazy no good, in my opinion.

You're better than that I'm sure!
 
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Old 12-06-11, 02:48 PM
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thanks for the reply. i actually got lucky i had one of the symptoms the first time i switched it on when i got home from work. here's what i observed (forgive my crude descriptions):
1-heard the click of the tstat calling for heat
2-heard a fan come on
3-saw a coathanger looking thing heat up red hot and then flames from the furnace started blazing
4-there was a short burst of clicks from the bottom of the furnace box and it looked like the furnace kinda stumbled for moment and then went back to normal.
There were no more clicks and the furnace appeared to function like normal. There is nothing in the bottom panel of the furnace except the control board i believe so I guess that is the culprit?
 
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Old 12-07-11, 04:08 PM
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It could be as simple as a dirty flame sensing rod. Most furnaces have a sensor which sticks into the flame (usually on the opposite end of the burner rack from the ignitor). This rod is usually held in place with one 1/4" hex head screw & has one wire going to it. Here are pictures of several different ones. Flame Sensors - Free Shipping | Bell Parts

Remove the rod & clean the metal rod portion which sticks into the flame with a piece of scotch brite or very fine sandpaper then re-install.
 
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Old 12-08-11, 03:06 PM
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are you referring to this thing (cant see it very well but the arrow points to it)

rod looking thing looks like it is right between the coathanger deal that glows red hot.
 
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Old 12-08-11, 07:01 PM
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That could be the flame rod but what you describe sounds like you have hot surface ignition & I've never seen a hot surface flame rod which looks like that. Above & right of the arrow looks to be something with a single wire. It appears to be in front of the burner on the right. Check it out. That might be the flame rod.
 
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Old 12-08-11, 11:25 PM
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It looks to me like a Honeywell intermittent ignition pilot burner. Notice the pilot tubing visible below the burner manifold.

Do the wires coming from what I'm calling a pilot burner go to plastic box about 4x6" that says Honeywell on it?
 
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Old 12-09-11, 03:57 PM
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I too thought it looked like an intermittent pilot ignition system but was thrown by the "glows red". I guess the hood would glow, duh.

I'll now take self to the woodshed for a good talking to.
 
 

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