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|12-02-2007, 03:43 PM||#1|
Join Date: Dec 2007
Posts: 1Rewards Points: 10
I spent the morning reading through all the carrier issue related threads. Lots of good information here.
My unit uses a 3 wire ignitor. This ignitor has been replaced 3 or 4 times in the past 3 years.
I didnt replace it, I had a local hvac guy come out and he replaced it, and the excitor motor, and the circuit board, thermostat (x2), and the burner unit. Aside from the near perfect sheetmetal ducting, I swear, just abot everything has been replaced in this furnace.
Finally he said I was due for a new furnace, that it would of been cheaper than calling him everytime the heat went out.
Well.. this is my first home, I work 60 hours a week, I never liked the thought of screwing around with a system that could potentially blow my house up.
Well, I got a quote, just shy of 2 grand (american) to replace it with a 95% effecient model. I declined, rolled up my sleeves and dug in.
Same deal as always, it would fire, then die out and not run after about an hour or two. I ohmed out the ignitor, and sure enough it was reading about .6 ohms.. All the other ones were similar, .3 to .6 ohms, and one was reading as an open. (this is measuring between the two outer most conductors.)
So, I replaced it.. But not before taking a measurement before hand. 1.7 ohms on the new one...
One month goes by, we get nailed with an ice storm, the house is a frigid 60 some odd degrees this am.. (normally set at 72-74..)...
Thats where I started reading here... As stated lots of good info.. I checked the voltage on the pressure switch, looked like what I would expect... I cleaned every circuit board contact with acetone, alchol and a fine file... ohmed out the ignitor (which wasnt firing at all, no spark, no pilot flame, just the motor would run, and no magic... )
So, I took apart all the other old ignitor looking for a common failure mode... All of them looked about the same... dirty.. Figured it wouldnt hurt so I popped open the new one, and I wish I would of taken pics.
Prying the tabs up on the bottom of the device, it comes apart with reletive ease. all the gold contacts on the inside were green with corrosion.. This is less than 30 days old... Too much moisture in the mix? Hrmm.. not sure why or what, but after cleaing it, the impedance went back to 1.7-1.8 ohms once reassembled... (just like new).
So, I reinstalled it and nothing... bupkiss... nodda...
I pulled the top vent tube that I assume vents out all the exhaust from the pilot area... Out flows years worth of debris... leaves.. dirt, seeds... grass... nice.. almost a gallon bucket full of debris... Hrmm... well that may be an issue...
Head out side to inspect what was up... A white plastic target bag had found its way into the intake pipe as well... probably the reason it wasnt trying to fire.
Well with all the lines clear and the ignitor tucked back up in its normal position, the furnace fired right up..
Not sure why its eating ignitors so often, but I wonder if it had more to do with obstructed pipes?
Perhaps the ignitor placement is too deep into the flames?
I noticed one thing though.. the spark mechanism seemed to continue to run, even after the furnace fired and stayed on.. I could peer into the little window and could see it sparking away, even though the pilot was lit, as was the burner.
IS THIS Normal?
Last edited by spyjmr; 12-02-2007 at 03:47 PM.
|12-02-2007, 07:27 PM||#2|
No, not normal, the spark ignitor also has a flame sensor either attached to it, or someplace else, that not getting the signal to tell it to stop sparking.
Alot of times it's the spark tip that's the sensor.
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