My Gas Furnace Won't Light.....


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Old 02-24-06, 09:35 PM
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My Gas Furnace Won't Light.....

I HAVE A LENNOX GAS FURNACE, MODEL # G2603-75-1, (IT IS ABOUT 10 YEARS OLD) AND WHEN THE FAMILY GOT OUT OF BED THE OTHER DAY, I DISCOVERED THAT THE AIR COMING OUT OF THE VENT WAS COLD. AFTER CHECKING THE FURNACE, I DISCOVERED THAT THE IGNITER WAS SPARKING, BUT THE BURNER WOULD NOT LIGHT. I FOLLOWED THE INSTRUCTIONS, AND SHUT OFF THE GAS CONTROL VALVE, AND WAITED 5 MINUTES, THEN RESET THE GAS CONTROL VALVE…..AFTER TURNING THE POWER BACK ON, THE BLOWER CAME ON, THE IGNITER SPARKED, BUT THE BURNER STILL DID NOT LIGHT…..ANY IDEAS ON WHETHER THE PROBLEM IS THE GAS CONTROL VALVE, OR SOME OTHER CAUSE?....ANY SUGGESTIONS ON WHAT TESTS SHOULD BE DONE TO NARROW DOWN, THE EXACT PROBLEM?....THANKS.
 

Last edited by GETFURIOUS; 02-24-06 at 10:47 PM.
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Old 02-25-06, 07:30 AM
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Ignition module?

I posted this on another thread earlier in the week:

I've been fighting one of my two 15 year old trane furnaces installed in my house all winter. If I would fiddle with it, it would run OK for an hour or maybe a day then quit again. Vent blower would run fine and furnace blower would run fine. Upon reset the igniter would light, but the gas would not come on. If I regrounded the Fenwal ignition controller it would seem to light off right away. I changed out that ground wire three times, then gave up on the controller.

I bought a Honeywell S8910U Universal Hot Surface Ignition module off Ebay for $75 last week. It took about an hour to install it, including decoding the wiring and crimping on new connectors. Furnace lit right off, and hasn't missed a beat since. Wish I would have done it at the beginning of the winter.
 
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Old 02-25-06, 08:31 AM
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Getfurious

If the ignitor is sparking, yet the pilot does not light, the problem could be a dirty pilot orifice.
 
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Old 02-26-06, 11:45 AM
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If the ignitor is sparking, yet the pilot does not light, the problem could be a dirty pilot orifice.
FIRST, LET ME SAY THANKS FOR THE INFORMATION…..SINCE THIS FURNACE DOES NOT HAVE A STANDING PILOT, SHOULD THERE BE A PILOT ORIFICE TUBE?....IF THERE IS A PILOT ORIFICE TUBE, AND IT IS DIRTY, IS IT RECOMMENDED THAT IT BE CLEANED OR REPLACED?....THANKS.
 
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Old 02-26-06, 11:54 AM
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Originally Posted by indy-diy
I posted this on another thread earlier in the week:

I've been fighting one of my two 15 year old trane furnaces installed in my house all winter. If I would fiddle with it, it would run OK for an hour or maybe a day then quit again. Vent blower would run fine and furnace blower would run fine. Upon reset the igniter would light, but the gas would not come on. If I regrounded the Fenwal ignition controller it would seem to light off right away. I changed out that ground wire three times, then gave up on the controller.

I bought a Honeywell S8910U Universal Hot Surface Ignition module off Ebay for $75 last week. It took about an hour to install it, including decoding the wiring and crimping on new connectors. Furnace lit right off, and hasn't missed a beat since. Wish I would have done it at the beginning of the winter.
WHAT LED YOU TO THE IGNITION MODULE, AS THE CAUSE OF THE PROBLEM?....ALSO, WHY DID YOU CHOOSE THIS PARTICULAR HONEYWELL AS THE REPLACEMENT/SOLUTION?....WHAT TESTS CAN I DO TO CONFIRM THAT THE PROBLEM IS OR IS NOT, THE IGNITION MODULE?....THANKS.
 
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Old 02-26-06, 05:35 PM
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Pilot

I am only presuming there is a pilot because very few furnaces use a direct spark to main burner ignition system. If there is a pilot tube on the gas valve, try disconnecting it & blowing the pilot assembly out with canned air. Intermittent pilots are far more subject to plugging than standing pilots.
 
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Old 02-26-06, 06:14 PM
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Originally Posted by GETFURIOUS
WHAT LED YOU TO THE IGNITION MODULE, AS THE CAUSE OF THE PROBLEM?....ALSO, WHY DID YOU CHOOSE THIS PARTICULAR HONEYWELL AS THE REPLACEMENT/SOLUTION?....WHAT TESTS CAN I DO TO CONFIRM THAT THE PROBLEM IS OR IS NOT, THE IGNITION MODULE?....THANKS.

Good questions.

I didn't know the ignition module was bad - in fact I thought it wasn't since electronics usually work or don't work, no in between. But I had checked all the other sensors and switches with my meter, and it just seemed like the module was the only thing left.

About choosing this honeywell - again a bit of a guess that it would work. I looked at the specs on the old one, and they seemed to match the specs on this new one. It said it was a "Universal replacement" but didn't list my old one in the ones it was supposed to replace.

I found a replacement fenwal like I had, but it was on backorder, and cost $185 - no returns. So I figured I was taking a bit of a risk with the Honeywell at $75, but not as much as the Fenwal. I had experience with one of those ignition modules giving me fits on a water heater a few years ago, so I thought it was a good bet.

The only tricky part was that the wiring wasn't labeled the same between the old one and the new one, I had to do a little matching to the installation diagram on the Honeywell - but it wasn't too hard, and worked the first try.
 
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Old 02-26-06, 06:17 PM
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P.S. - if yours is a spark ignition, you'll probably need a different model - mine uses a hot surface ignitor rather than a spark ignitor - I think I saw the spark models on Ebay as well.
 
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Old 02-26-06, 07:45 PM
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Originally Posted by Grady
I am only presuming there is a pilot because very few furnaces use a direct spark to main burner ignition system. If there is a pilot tube on the gas valve, try disconnecting it & blowing the pilot assembly out with canned air. Intermittent pilots are far more subject to plugging than standing pilots.
THANKS FOR THE INFORMATION.....I WILL CHECK THE TUBE THAT GOES FROM THE GAS CONTROL VALVE TO THE IGNITER AREA, AND LET YOU KNOW IF THAT WAS THE PROBLEM.....
 
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Old 02-26-06, 07:48 PM
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Originally Posted by indy-diy
Good questions.

I didn't know the ignition module was bad - in fact I thought it wasn't since electronics usually work or don't work, no in between. But I had checked all the other sensors and switches with my meter, and it just seemed like the module was the only thing left.

About choosing this honeywell - again a bit of a guess that it would work. I looked at the specs on the old one, and they seemed to match the specs on this new one. It said it was a "Universal replacement" but didn't list my old one in the ones it was supposed to replace.

I found a replacement fenwal like I had, but it was on backorder, and cost $185 - no returns. So I figured I was taking a bit of a risk with the Honeywell at $75, but not as much as the Fenwal. I had experience with one of those ignition modules giving me fits on a water heater a few years ago, so I thought it was a good bet.

The only tricky part was that the wiring wasn't labeled the same between the old one and the new one, I had to do a little matching to the installation diagram on the Honeywell - but it wasn't too hard, and worked the first try.
THANKS.....
 
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Old 03-01-06, 09:19 AM
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OKAY…..I CLEANED THE GAS SUPPLY TUBE RUNNING FROM THE GAS CONTROL VALVE TO THE IGNITER…..AND THE IGNITER STILL SPARKS, BUT THE FURNACE STILL WON’T LIGHT…..THE DRAFT FAN AND THE BLOWER BOTH COME ON, BUT NOT THE BURNER…..I SUSPECT THAT THE GAS CONTROL VALVE MAY BE THE CULPRIT, BUT I WANTED TO KNOW IF ANYONE HAS ANY TESTS THAT I CAN DO TO CONFIRM THIS, BEFORE I SPEND MONEY ON THE GAS CONTROL VALVE…..THANKS.
 
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Old 03-01-06, 05:42 PM
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Checking gas valve

During the sparking process, you should have 24 volts AC between terminals mv/pv (common) and pv. If no 24 volts, some other problem. If you get 24 volts, the pilot orifice could still be plugged & not allowing gas into the burner area. Remove & clean the pilot orifice or replace it (usually easier).
After cleaning/replacing the pilot orifice if you still get no pilot, the gas valve is likely at fault.
 
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Old 03-03-06, 07:33 AM
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Originally Posted by Grady
During the sparking process, you should have 24 volts AC between terminals mv/pv (common) and pv. If no 24 volts, some other problem. If you get 24 volts, the pilot orifice could still be plugged & not allowing gas into the burner area. Remove & clean the pilot orifice or replace it (usually easier).
After cleaning/replacing the pilot orifice if you still get no pilot, the gas valve is likely at fault.
I TESTED THE VOLTAGE, AND DURING THE SPARKING PROCESS, I AM GETTING 15 TO 19 VOLTS…..GIVEN THIS RESULT, WHAT DO YOU THINK IS THE CAUSE OF THE PROBLEM?.....THANKS.
 
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Old 07-21-12, 06:11 PM
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Spa Heater not firing

Hello,
I have a Teledyne heater LLD 400. The HSI igniter glows OK but the gas valve does not open. I measured the voltage coming to the fenwal controller and it's about 19 v. Coming out of the controllers and at the gas valve it's about 15.5 v.

Is this voltage enough to activate the gas valve or should be 24V minimum?

I checked the transformer output and it has 28 v.
Why would the input voltage, to the controller, be less than 24v?

any help is appreciated.
 
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Old 07-25-12, 04:17 PM
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Make sure ALL wiring connections are clean & tight. Spas, hot tubs, pool heaters, etc. are notorious for having corrosion problems. You are measuring AC volts, not DC, correct?
 
 

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