Please Help

[tigerjon]

We live in Kansas City, where this evening it is very cold. About 15 minutes ago I noticed our furnace (G40UH) is not running. We have the stat (Lennox Elite Series) set to 74, but the temp is down to 72. When I first noticed the problem the Aux Heat showed to be running, but the furnace was not. I went downstairs to check the breaker and furnace on/off switch but everything appears okay. The status lights of the furnace are flashing green back and forth. This same problem took place last winter so we had a United H&C guy come out. The only thing he could see was the little pin/rod that detects the flame (forgot the name) was very dirty. He cleaned it and everything was good. It happened a few weeks ago (I just so happened to kick up the stat a degree. I was thinking that I may have done it right after the furnace had been running and with the wait period, it was thrown out of whack). Since I remembered what had happened last winter, I shut off the furnace and took out the pin. It didn't look very dirty, but I did wipe it off with a rag. Placed it back in and after I turned the furnace back on, it fired up. Now, it's happening again. This time I have not taken the pin out because I figure it is clean. Before I call the expert and pay an after hours fee, is there anything simple I may be missing. Thank you for any help.

[tigerjon]

Update: it has started running again, but I have to figure out why this is happening. Could something as simple as manually kicking the stat up a degree when it is following a schedule and has just finished a cycle rattle it when it is single digit cold outside? Thanks.

[SJProwler]

If the unit appears to be running and then shutting down before the thermostat is satisfied it may be shutting down on the high limit switch. Verify that your filters are clean and that all registers are open.

If you still experience the problem it's time to call for service.

Beyond that advice this is not a DIY site.

[tigerjon]

A new observation; again, the stat is set to 74, but the furnace is not kicking on until the temp reaches 72. What gives? Thanks.

[tigerjon]

A new observation; again, the stat is set to 74, but the furnace is not kicking on until the temp reaches 72. What gives? Thanks.

Also, the stat will start calling for Aux Heat at 74 and will remain displayed all the way to 72 and then the Aux Heat will finally kick on. Could this be due to a incorrect setting with the stat? Thanks.

[oregonhvac]

Your gas furnace has numerous safety controls that check and re-check system operation, before and after ignition. It sound like your at the point where maybe you should call for help. A small amount of money is well worth your families safety.
Good luck!!

[tigerjon]

Your gas furnace has numerous safety controls that check and re-check system operation, before and after ignition. It sound like your at the point where maybe you should call for help. A small amount of money is well worth your families safety.
Good luck!!

So, I guess there is nothing I can check myself without blowing my home up. I understand people have to make a living (I do too), but I would hate to drop $130+ to have someone tell me my thermostat was set wrong.

[big sky hvac]

The alternating green lights indicate a lockout due to failed ignition. The best thing you can do is call a service company out in the morning and have them perform a tune-up on your furnace. They'll be able to get you going again.

[tigerjon]

I will say that some here will frown on me for what I did last night, but it got the furnace working. Also, last winter when this happened, the UHC guy showed me the most likely reason why it happened and how to try this trick if it ever happens again. I shut off my furnace (at the furnace switch...not at the stat). I then flipped the breaker. Next I removed the ignitor (I believe this is what he called it) and cleaned it off with a wire brush. I put it back in place, flipped the breaker, and flipped the furnace switch. The furnace started running immediately and worked fine through the evening. This is almost the same thing I did a few weeks ago when this happened, but that time I just wiped the ignitor with a rag...no wire brush like the tech used. Anyway, my wife is going to keep and eye on it and if it starts up again I will call the United guy for sure. I read another thread where the poster was concerned that the stat should not be played with during really cold stretches. Is this the case? Normally we have our state to drop to 70 during the day when we're gone but up to 74 so it is warmer when we return. When the temp. demands gas heat, is it better to leave at a consistent temp? Thanks again.

[big sky hvac]

I will say that some here will frown on me for what I did last night, but it got the furnace working. Also, last winter when this happened, the UHC guy showed me the most likely reason why it happened and how to try this trick if it ever happens again. I shut off my furnace (at the furnace switch...not at the stat). I then flipped the breaker. Next I removed the ignitor (I believe this is what he called it) and cleaned it off with a wire brush. I put it back in place, flipped the breaker, and flipped the furnace switch. The furnace started running immediately and worked fine through the evening. This is almost the same thing I did a few weeks ago when this happened, but that time I just wiped the ignitor with a rag...no wire brush like the tech used. Anyway, my wife is going to keep and eye on it and if it starts up again I will call the United guy for sure. I read another thread where the poster was concerned that the stat should not be played with during really cold stretches. Is this the case? Normally we have our state to drop to 70 during the day when we're gone but up to 74 so it is warmer when we return. When the temp. demands gas heat, is it better to leave at a consistent temp? Thanks again.

I doubt it was the ignitor that you cleaned. This is why having a regular maintenance performed on your furnace would have prevented this problem. I personally wouldn't have used a wire brush, but you were able to get it going so you weren't cold. I would still recommend having a tune-up done on the furnace though.

[Roadhouse]

RH....

That wasn't very nice. This guy came here for help, yes, he will need a pro to find the real cause but we don't have to be mean.


post edited

[tigerjon]

I doubt it was the ignitor that you cleaned. This is why having a regular maintenance performed on your furnace would have prevented this problem. I personally wouldn't have used a wire brush, but you were able to get it going so you weren't cold. I would still recommend having a tune-up done on the furnace though.

You are correct, it was the flame sensor. I spoke with UH&C today and they said that very well could have been the problem and to keep an eye on it. If the problem persists we will definately call them out to our home. The reason I used a wire brush is because that is what the tech used last winter.

[big sky hvac]

You are correct, it was the flame sensor. I spoke with UH&C today and they said that very well could have been the problem and to keep an eye on it. If the problem persists we will definately call them out to our home. The reason I used a wire brush is because that is what the tech used last winter.

I guess a wire brush would work, but I've always heard from manufacturers that they recommend steel wool or a scotchbrite pad. Me personally, I use a scotchbrite pad. I did work with a guy once that scraped them off with his pocket knife, although I wouldn't recommend that as a common practice, maybe if that's all you have in a pinch.

[Roadhouse]

RH....

That wasn't very nice. This guy came here for help, yes, he will need a pro to find the real cause but we don't have to be mean.


post edited

Yoinks! Perhaps I could've worded myself better. Certainly was not meant to be not nice, just give him something to ponder upon such as, "Oh geez, perhaps I shouldn't have been messing with this.." as he's doing.

Luckily it was not the ignitor because if it were, well, the rest of know what could happen and how to handle that particular component so it won't, that's all.

OP, not certain if you caught the previous original post but I wasn't trying to be "not nice", not in any way, but rather get you to stop in your tracks and think things through before you cause bodily harm to yourself which you most certainly can when it comes to this, along with messing up the component you might be trying to fix.

Be careful.

[tigerjon]

I guess a wire brush would work, but I've always heard from manufacturers that they recommend steel wool or a scotchbrite pad. Me personally, I use a scotchbrite pad. I did work with a guy once that scraped them off with his pocket knife, although I wouldn't recommend that as a common practice, maybe if that's all you have in a pinch.

It's funny, I just now got finished talking to a guy I work with that bought a spare one for his funace he keeps around in case of an emergency. He says his appears to be all ceramic. Mine looks almost like a firing pin; about 9/64 in dameter, about 3 inches long, metallic with the little connector at the top.

[Dad]

Your friend has what is generically called a Glow Coil and you have a Spark Ignition.

A Glow Coil is very sensitive and will break as easily as your Grandma's China. He's smart to keep a spare. But again, you have a different type of ignition.

These guys are correct. You may have temporarily solved your symptom but you haven't found the cause. Last year when the tech came out the first time he may not have been able to find an intermittent issue with your system and simply got you up and going again.

[t527ed]

G40 uses a surelight ignitor, very reliable ignition.
still uses the same pita flame sensor though.

[keeplearnin]

Again... edited post.

You are a guest on this site. You will please be polite or you will no longer post here.

thx

[Roadhouse]

I'm confused, is this the flame sensor or the ignitor we're talking about?

[tigerjon]

Again... edited post.

You are a guest on this site. You will please be polite or you will no longer post here.

thx

Look, KL, let me tell you something. For a living I sell equipment used on cranes and for fall protection. If this stuff is not used properly, you can die. If a client or a potential client calls me with a question that I can answer by phone or email without putting him/herself along with anyone else at risk, I have no problem offering a little free advice...after all, I don't look down on these people as complete dumbasses that are helpless. I know that there are some things they can, believe it or not, do for themselves without me charging a fee for a class. For chrissakes, quit whining. I got the problem fixed, the damn thing is working, I did it the way the tech showed me how to do it, if the problem persists I'll call them up and they can make some money off me and I'll have no problem doing it, as they have been helpful and friendly in the past...by phone and in person. Nuff said!

[tigerjon]

I'm confused, is this the flame sensor or the ignitor we're talking about?

It's the FS.

[keeplearnin]

Let me get this strait, your a salesman, I would have never guessed.

[big sky hvac]

It's funny, I just now got finished talking to a guy I work with that bought a spare one for his funace he keeps around in case of an emergency. He says his appears to be all ceramic. Mine looks almost like a firing pin; about 9/64 in dameter, about 3 inches long, metallic with the little connector at the top.

Your coworker may be talking about a spare ignitor, not a flame sensor. Your furnace uses a Surelight ignitor, as was stated earlier. It is silicon nitride, and for the most part, very reliable. Your flame sensor is one of the safety controls incorporated into the furnace. The circuit board sends DC line voltage to the flame sensor, when the burners light, they complete the circuit to ground which produces a uAmp signal back to the board(or igntion control). This tells the circuit board whether or not the burners are lit. If the signal is weak, the board sees that as no flames present and it de-enerigizes the gas valve. There are many things that can cause a flame sensor to get dirty. One of the biggest is dryer lint. The majority of furnaces I work on are located in the same room as the washer/dryer. If the dryer vent is not connected properly, excess lint enters the air and eventually makes it to the furnace. A lot of clothes today have plastics in them, like polyester fibers. These can "coat" the sensor and weaken the signal. I've also seen the dust from litter boxes cause the problem, as a lot people put their litter boxes right in front of or beside the furnace. I would still have a tune-up performed on the furnace to prevent any further problems and to determine why it caused you problems. The furnace may not be grounded properly or the circuit board could be bad.

[tigerjon]

Let me get this strait, your a salesman, I would have never guessed.



Yeah, a successful one too because I don't nickle and dime my clients when they want to know how to do something they can handle on their own. You should try it, you might not be so bitter about someone getting a little free advice. I'm done with you, you're wasting my time.

[keeplearnin]

Very well put big sky.

[keeplearnin]

Then you can afford a service call correct? I'm not bitter I'm just stating facts. you said you were a salesman that's in your post I just acknowledged it. No hard feelings, your just a little defensive I understand so am I.

[tigerjon]

Your coworker may be talking about a spare ignitor, not a flame sensor. Your furnace uses a Surelight ignitor, as was stated earlier. It is silicon nitride, and for the most part, very reliable. Your flame sensor is one of the safety controls incorporated into the furnace. The circuit board sends DC line voltage to the flame sensor, when the burners light, they complete the circuit to ground which produces a uAmp signal back to the board(or igntion control). This tells the circuit board whether or not the burners are lit. If the signal is weak, the board sees that as no flames present and it de-enerigizes the gas valve. There are many things that can cause a flame sensor to get dirty. One of the biggest is dryer lint. The majority of furnaces I work on are located in the same room as the washer/dryer. If the dryer vent is not connected properly, excess lint enters the air and eventually makes it to the furnace. A lot of clothes today have plastics in them, like polyester fibers. These can "coat" the sensor and weaken the signal. I've also seen the dust from litter boxes cause the problem, as a lot people put their litter boxes right in front of or beside the furnace. I would still have a tune-up performed on the furnace to prevent any further problems and to determine why it caused you problems. The furnace may not be grounded properly or the circuit board could be bad.

BSH,

Great info and thank you. Our furnace is quite a ways away from our dryer, but that makes perfect sense as our home can get a little dusty. In fact, the lady I spoke to from UH&C this morning says that they can install a clean air system to our furnace that can help out with a problem like excessive dust. We may just do that. Thanks again.

[Roadhouse]

I once worked with a guy, a fellow cyclist, who was a crane operator at The Port of Houston, The Ship Channel, who loaded and off loaded ships and trucks who was earning six figures doing that and teaching, contract, new crane operators.

He got me a job working with him at his friend's machine shop, turning lathes, that he helped at from time to time.

Problem was, this guy I knew, the crane operator, would continually stick the blade in too far, sending metal shrapnel as if from a bomb all over the shop. I quit soOn after as that isn't how I wanted to go.

Moral of the story is what may be goOd for the goOse is not neccassarily gOod for the gander.

Well that and, "You are no Daisy, you are no Daisy at all." ~ Doc Holiday