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Old 12-23-08, 06:14 AM
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quick question

What does a flame sensor do? and would it have anything to do with a furnace not igniting? thanks
 
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Old 12-23-08, 06:40 AM
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The flame sensor proves there is a flame and keeps the gas valve open, and yes if not working it will not allow the furnace to light. If it does light it will go out very quickly. If this is your problem your could remove it and clean it with sand cloth until you get a replacement.
 
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Old 12-23-08, 10:37 AM
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Mr. Happy,

Is it common for the flame sensor to go out often? I had mine cleaned in 2004 and then problems during 2007 again. I replaced the flame sensor in 2007 and it seems to not be working again. Could something else be faulty that is causing this to not work?

I am assuming this is the flame sensor or ignitor...the furnance will turn on, the flame will light up, and the flame will go out, start again, three times, and then the whole furnance turns off with an error message that the flame could not be established. When I take out the sensor or ignitor...not sure what it is called, it is hot to the touch.

Any help would be appreciated.

Thank you!
 
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Old 12-23-08, 10:59 AM
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Originally Posted by KoriHeatNoWork View Post
Mr. Happy,
I replaced the flame sensor in 2007 and it seems to not be working again. Could something else be faulty that is causing this to not work?
I am assuming this is the flame sensor or ignitor...the furnance will turn on, the flame will light up, and the flame will go out, start again, three times, and then the whole furnance turns off with an error message that the flame could not be established. When I take out the sensor or ignitor...not sure what it is called, it is hot to the touch.

Any help would be appreciated.

Thank you!
I would check the gas valve coil. If you are having that much trouble with the flame going out and the sensor has been cleaned and replaced, I would start looking for other faults. Follow the wires to the gas valve, if you have mechanical ability to ID the coil, check voltage first and the check the resistance. A weak coil could cause the valve to close. There could also be other things involved, like low gas pressure. Check the Gas vent by the meter for any clogs.
 
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Old 12-23-08, 11:42 AM
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If it is the coil, is that easy to replace? If it is a clog in the gas valve, is it safe for me to try to clean it by myself (after I turn the gas off)?
 
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Old 12-23-08, 11:55 AM
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If it's the coil just replace the gas valve, if you find the right supplier it should be under $100, if it's a clog.. no need to turn off the gas, look for a small 1/4" tube off the regulator and do a visual fist (no smoking) I do not know the part of the country you are from, but it could be snow, ice, if you have that, or it could be a small insect.
 
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Old 12-23-08, 12:44 PM
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Thank you for your time and help! I'll check it out tonight and hopefully be able to figure it out!
 
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Old 12-23-08, 01:58 PM
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Do you have the ignitor where it glows real bright and lights the furnace? Or a pilot that lights first?
 
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Old 12-24-08, 12:44 AM
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I have an ignitor that glows real bright and lights the furnace, but I thought a pilot light was somehow involved, no? Does the ignitor light the pilot and then that lights the furnace? Sorry, I know I'm really inexperienced in this area!

I can't figure out where to look for the gas coil valve. I follow the gas line from where it hooks outside of the furnance and all the way to the burners. (it looks like it is black piping all the way, but it does go through a silver container before that last of the black piping that leads to the burners) I can't really tell if it is clogged unless I should be loosening the joints? It looks like there is grease around the joints of where different pipes meet.

I appreciate your time, thank you.
 
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Old 12-24-08, 01:02 PM
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If you had just the glow coil (HSI hot surface ignitor) that directly lights the burners, then you will see 2, usually white thin braided wires, traveling together into the combustion chamber. And the piping from the gas valve would only have that 1/2 inch black pipe coming out of it heading into the combustion chamber. If you also had a pilot, you would also see coming out of that gas valve, about a 1/4 inch size aluminum tubing that heads into the combustion chamber.

So what do you have?
 
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Old 12-24-08, 01:56 PM
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From memory, I only have black piping, so there must not be a pilot light.
 
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Old 12-25-08, 12:01 PM
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Originally Posted by KoriHeatNoWork View Post
...the furnance will turn on, the flame will light up, and the flame will go out, start again, three times,
Since from your last post it sounds like you just have the ignitor, - and from the quote above here you said you have flame and it goes out - did you take out and polish up the flame sensor rod?
 
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Old 12-25-08, 10:51 PM
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Heating Help

If you have replaced a flame rod more than once most times it is really a problem with grounding. control voltages are very sensitive to high resistance due to the nature of low amounts of electrical force (voltage) Usually when flame rods are replaced the real problem was a corroded, dirty or loose wire and in taking apart and refastening the problem is solved. Any time I have a problem with flame recognition, before I replace anything I take apart and refasten all the control wiring connections in the furnace and that, more often than not, cures the symptom.
 
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Old 12-26-08, 09:18 AM
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Since my last post, I had replace the ignitor. Same problem. I turned the furnace off for a couple of days and then figured it must be something else, so I took out the new ignitor (it was supposed to be a universal, better, upgrade, but it didn't fit as well, so I wasn't comfortable with it) and then put the old ignitor back in (I had previously cleaned it, but after first cleaning it and putting it back in, it didn't fix the problem). Just b/c I was curious, I started the heater again. This was around 1:30 in the morning on Christmas Day...surprisingly, the heater worked! It worked all day on Christmas Day and now it is no longer working...Christmas miracle, I don't know...

Now, to your point on the wires, would it be just the two wires that go into the ignitor? Or should I be checking some other wires?

Thank you for your help.
 
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Old 12-26-08, 10:20 AM
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Again I would check the gas valve. Micro volts keep it open, if not sensing voltage; it won't stay open, causing flame to go out.
 
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Old 12-26-08, 10:52 AM
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How exactly do I check the gas valve? I'm sorry I am not that experienced at this. Is the gas valve the two openings from the gas that go towards the burners? Or is the gas valve the piece of the black piping that comes out of the silver (combustion chamber??) container and goes towards the burners? The second joint that I described has grease around the threads.
 
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Old 12-26-08, 11:04 AM
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Originally Posted by KoriHeatNoWork View Post
How exactly do I check the gas valve? I'm sorry I am not that experienced at this. Is the gas valve the two openings from the gas that go towards the burners? Or is the gas valve the piece of the black piping that comes out of the silver (combustion chamber??) container and goes towards the burners? The second joint that I described has grease around the threads.
It is behind the door of the furnace,it has either a dial that reads on-off or a switch that reads on-off. It is a cast aluminium box with 2-4 wires on top.

If you do not know how to identify this part I would highly recomend seeking help from a pro that can go to your place an fix it for you.
 
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Old 12-26-08, 01:19 PM
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okay, I know what piece that is. It has a blue switch that flips up and down for on and off. Is it too dangerous for me to try and deal with this piece? I have only replaced the ignitor in the past.
 
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Old 12-26-08, 01:45 PM
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I can't understand why you went and invested in a new ignitor, when you say it glows and you do get fire.

We have been suggesting the flame sensor as being dirty (albeit rather often for some reason, if that is the case again), bad connections involving it, or perhaps the gas valve shutting back down.

Do you own a volt-ohm meter (multimeter) to test with?
 
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Old 12-26-08, 11:10 PM
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No, I don't own a multimeter.

I just got a new ignitor b/c the problem this time seemed very similar to the last time (2007 and 2004)...but it clearly was not the same. I had my furnace off all day and turned it on when I got home from work, it is working now, but I don't know how long it will work...as it worked all day yesterday and then stopped when it was time to go to bed. Does this still sound like a gas valve problem? Or should I unhook and re-do the wiring on the two white braided electrical lines on the ignitor?
 
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