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Discussion Starter #1
I have a lennox gcs26-036-75-2pa, when you turn on the heaeter
the ignitor sounds like it humming but i cant see a arc. It also seems as though that when it signals for the ignition it stops and then the gas turns on after the ignition stops . Please
help. What controls the timing between the spark and gas.
Please help.
 

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Discussion Starter #8 (Edited)
There are gas nozzles that spray into runners, the middle runner at the end has a electric arc in front of runner with gas going through the runner and hitting the arc of electricity. I have it worked on several times and
today i installed a new ignitor( i guess is the name part that
sparks and not working. Before when heat guy came out whe watched it ,gas looked as if it was spraying right on the flame but nothing was happening and then sometimes it would work now nothing at all.
 

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you can see it sparking but not lighting the gas ?? Or just not sparking ?? Sorry for all the questions But I 'am tryng to determine the ignition of this furnace
 

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Discussion Starter #10
i appreciate the time. i have been told that you may not be able to see the spark during the day due to the intensity of the bluid light, but as of
early today after i replaced ignitor i cannot see a spark, only here it like
electricity arcing.
 

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Discussion Starter #12
is the gap already set when you buy a new one, or what should it be. when the heat guy was here he thought that and reset set the gap and
afterwards we watched in amazment as gas sprayed on a bright blue arc in the center of the gas nozzle and nothing seem to happen. low gas
pressure through valve, or weak spark?. and when you here the noise like its trying to spark it stop befor gas starts to spray.
 

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could be the box/ board that controlls the spark.. If gas comes into the chamber & doesn't ignite.. It could be weak spark. The spark should be anywhere in the 10,000- 12,000 volt range.. , you should be able to see the spark
 

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Discussion Starter #14 (Edited)
I just went back out and tried it. It will have a light arc for about a half a seconde and then go away. Then right after gas
comes on i think the spark doesnt last long enough and is weak. Doesnt the board control all of that.
HOW LONG SHOULD SPARK ARC ARC ROD FOR? I THINKG LONGER THAN A SPLIT SECOND. IT SEEMS THAT IT DOESNT SPARK LONG ENOUGH FOR GAS TO ENGAGE ANDTRAVEL THROUGH PASSAGE.
 

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I just went back out and tried it. It will have a light arc for about a half a seconde and then go away. Then right after gas
comes on i think the spark doesnt last long enough and is weak. Doesnt the board control all of that.
HOW LONG SHOULD SPARK ARC ARC ROD FOR? I THINKG LONGER THAN A SPLIT SECOND. IT SEEMS THAT IT DOESNT SPARK LONG ENOUGH FOR GAS TO ENGAGE ANDTRAVEL THROUGH PASSAGE.


Yes the board or box( which ever you have ) controls the spark.. It should have a good strong spark & should spark long enough to ignite the burners ( with correct gas pressure).. Once burner flame is proved The spark should stop..If the gas is comming through at the correct pressure & it doesn't ignite within a few seconds, gas flow & spark will stop untill all gas is purged from the unit.. It should try again.. Most will try 3 times b-4 lock out. If this happens you will have to re- set the unit.. You might also check the wire to ine ignitor make sure you have good connection/ wire in good condition/ ground
 

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Discussion Starter #16
Okay, so the spark and gas at the same time should stay on for
a couple of seconds. So if system arcs for a half second and then gas sprays is it most likely because board not allowing
spark signal long enough? This has been going on for months with technicians coming over trying to fix and usually it never
happened whenn they were here. Now when it happens all the time i cannot find anyone. Can you tell me please when board sends signal through spark wire to ignitor how can i test to
verify either wire, board and something else is wrong.
 

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Discussion Starter #17
I have already tested wire and test ok. If it sparks erracticly and sometimes half second sometimes more is it the control
board. Sorry for the terms used i work on cars with some what
same devices, but completely different terms.
 

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I haven't seen it but the way you are describing If you aren't loosing spark through the wire or a short at the ignitor.. My best gusss from here is the board
 

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The board has a high voltage ignition transformer and it is weak/faulty and the board needs replacing and sometimes the ignition wire,as like a spark plug wire they deteriorate. May look good but can leak to ground. The gap between the igniter rods should be about 1/8" to 1/4" (use a drill bit) and you should remove the burners and clean the deposits off the ends of them and blow them out with air. This is a very similar unit:http://tech.lennoxintl.com/PDFs/9723d.pdf. The manual for yours doesn't show the igniter well.
 

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yuri, Don't see many lennox around here.. Was it a safe guess that it has/ had direct spark ign ? I know the goodman & some others had the spark transformer made to the board.wire runs from trans. on the board to the ignitor.... Is this 1 similar ?
 
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