Ignitor glows, but no ignition


  #1  
Old 11-09-01, 11:03 AM
ko49028
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I have a gas forced air furnace. It is approximately 8 years old. I can hear a fan kick in for approximately 30 seconds and then it shuts off for maybe a minute and starts over again. During this cycling the ignitor (replaced last winter) starts up and glows. It appears that it is not getting gas to burn. The blower fan does not kick in either. I assume that is because there is no heat to "blow". Does anyone have any ideas of what to check, or what may be wrong? Unfortunately, I am at work, and I do not have the brand name or model number with me.
 
  #2  
Old 11-09-01, 05:12 PM
HVAC Man
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when ignitor glows, listen for a "click" sound between the time it starts to glow, and the time the HSI (hot surface Ignitor) stops glowing, this is the solenoid in the gas valve opening, sometimes it's hard to hear the little click sound, check to make sure gas is on,and gas valve button is on, check to see if you have 24 volts going to the gas valve during the HSi glowing process, if you have access to a multimeter you can do this, if not, you can also try shutting power off to furnace at either the breaker, or a switch (if Installed) for a few minutes, then try again. thats about all I can suggest to you at this time.
Good luck
 
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Old 11-12-01, 01:46 AM
ko49028
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new info

Turns out that there is ignition. The failure indicator light has blinked in 6-blink increments on two separate occasions, however the manual only addresses up to 5 blinks. On two other separate occasions, it has blinked 4 times which indicates a failure of the high limit control. In speaking with a couple local techs and reading hundreds of threads on this site, they thought it would be that control or the flame sensor. Bypassing the high limit control eliminates my problem (for a temporary solution until I can get the part).

On a separate note, I did find one guy that had the part I needed, but he would only sell it to me if he installed it. He claimed the warranty would be void otherwise. I wasn't worried about the warranty, but he wouldn't sell it regardless.

I have become much more educated on my furnace from reading threads on this site. I applaud your work, as you are saving people money, educating them, and helping them to be a little more independent than they would have been.

Thanks again.
 
  #4  
Old 11-12-01, 02:56 AM
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Solenoids, Gas Valve, Restricted Flue Vent or Flame Sensor

Hello ko49028

I sure would like to know what part that guy you found wouldn't sell you??? You didn't state what part it was.

Below is a partial list of possible causes for the problem discription of your furnace.

Defective Glow Coil:
The glow coil may glow but just be too weak to allow current to continue to flow to the coils. The solenoid coils are also part of the electrical loop and may effect proper glow coil operation or functioning.

Defective Solenoids:
Solenoids also supply voltage to the glow coil and are part of the electrical loop. Take the entire gas valve unit to your local appliance parts store and have the entire assembly and parts tested.

Defective Gas Valve:
Remove entire unit as an assembly. Take the entire assembly to your local appliance parts store for testing. Gas valves are not repairable. Replacement is the only option if defective.

CAUTION: Do Not attempt to repair the gas valve! This is a non repairable item!

Flame Sensor:
This part is located on the burner assembly. If it's defective, it will cause the glow coil to not function or cause the problem your discribing. You can test this part with a continuity tester or an ohm meter. However, do not soley rely on this test to prove the part is functioning correctly.

Main circuit board may also be the problem.
Restricted flue venting system.
Dirty flame sensor element.
Bad or poor grounding of the flame sensor, spark modual, circuit board, vacuum air leakage, etc.

FYI:
The do-it-yourself person can do electrical tests and continuity tests on several of the parts. There are parts such as flame sensors, solenoids, gas valves, etc. when neither of these tests will provide proof positive the part is actually functioning correctly. Therefore, do not rely solely on either test.

TIP:
The only positive proof any part is functioning correctly, is to carefully remove the part or parts you suspect to be the potential problems, and have the local appliance parts store person run the required tests.

Appliance parts dealers carry replacement parts for all appliances and are listed in the phone book under appliances.

Refer to the manufacturers online web site for additional product information, problem solving methods, pictorials drawings and schematics, should they be available.

Regards & Good Luck
Gas Appliances Forum Moderator
Tom_Bart.... Enterprises
Energy Conservation Consultant & Natural Gas Appliance Problem Diagnostics Technician.
 
 

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