Burners won't stay lit

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  #1  
Old 11-17-00, 06:30 PM
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We have a Janitrol gas downflow furnace with a glow ignitor. The furnace will be 2 years old on 12-18. 1 1/2 years ago our house was hit by lightening & it traveled through the water heater & central air pump attached to the furnace. Last winter it short-cycled on occasion, but not too much. This winter it is horrible. We installed a Lux digital thermostat when we put in the new furnace, and I think it is working ok. The inducer fan will come on, the glow stick will ignite and the burners (4 of them) will come on for 10 seconds, the blower kicks on then, too, and the burners will shut down. The glow stick will ignite the burners again, etc. I have also noticed it doing other crazy things like the burners lighting, staying on for about 20 seconds, shutting down and then the blower kicks on for a few seconds, shuts off and the burners light again. This does not happen as much, but it has happened enough for me to notice. Our old furnace did this same type of stuff, and 3 furnace repair companies replaced the board (at a hefty fee), but that did not correct the problems, so we got our $ back from all of them & just replaced the furnace (for only about $400 more).
Also, I have the thermostat set to 72, the temp. on the thermostat will be registering at 73, and the furnace will kick on, which starts the whole process of the burners coming on & going off, etc. HELP!!! I don't want to have a repair guy come out if I can keep from it - that would be my Christmas money! Any ideas would be very helpful - please, if you respond, please be very descriptive as to what & where we are to look - we're not very handy sometimes.
 
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  #2  
Old 11-17-00, 07:14 PM
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Hi:Mellie0514

I read your discriptive posting several times and I gather your discribing the current conditions with the new furnace.

New furnaces have several complex safety systems which cannot be diagnosed without the proper tools and technical knowledge.

The conditions you discribed could be caused by any one of several systems in the furnace. The forced vent fan system, pilot prover, spark module, gas valve solenoid and several others.

Without going into detailed discriptions of those systems, try replacing the existing thermostat and see if it corrects the problem. It could be the heat anticipator in the thermostat causing the cycling on and off of the furnace.

Good Luck,
TomBartco
 
  #3  
Old 11-17-00, 07:15 PM
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Has anyone checked the control wiring between the stat and the furnace. If the wireing has more than 1 ohm of resistance it can cause problems. Also if it is grounded to the house via nail, staple, etc. Again wire gauge, janitrol recomends no smaller than 18 gauge. Replace the wire if you can, it's cheap.
 
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Old 11-18-00, 06:22 AM
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Sounds like the furnace is having trouble proving. The flame sensor needs to be cleaned.Don't clean the ignitor it would just break. But the flame sensor a metal rod that is in the flame can cause this problem.
Good Luck
Mr Foster
 
  #5  
Old 11-18-00, 10:07 PM
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Mr Foster:
Sounds like the furnace is having trouble proving. The flame sensor needs to be cleaned.Don't clean the ignitor it would just break. But the flame sensor a metal rod that is in the flame can cause this problem.
Good Luck
Mr Foster
<HR></BLOCKQUOTE>


Can you tell me how to locate the flame sensor, and what I should use to clean it with? We replaced the thermostat - thought we'd start with the cheapest thing first - but it is still short-cycling. The coil is lighting fine, but the burners just kick on and off. It seems like they are staying on even shorter periods of time now. If we clean the flame sensor and it still does this, what should we look for next? The motherboard doesn't have any trouble lights lit, so it thinks the furnace is fine. Do you think the board is shot already? We have a 5 year parts warranty, but labor is what is going to eat us up. Any more ideas would be greatly appreciated!
 
  #6  
Old 11-19-00, 08:02 AM
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The flame sensor is a metal rod that the flames heat up. The metal rod goes through a ceramic housing and is mounted by the burners. There would be ONE wire connecting the sensor the ithe ignition board(usually marked "sensor"). This rod gets an oxidation or insullating film on it that does't conduct electricty the module will shut off the gas.
Need to scratch, or clean with an abrasive(sand paper work great). When it can sense
 
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