Gas furnace don't start occasionally.

My gas furnace (Lennox GCS 16) occasionally stops working. It starts to work after I turn the main electrical switch off and on. Then, it works for a week and stops again. I called the gas furnace service and they replaced my filter and cleaned everything. The problem is that when they come and turn it on and off, it starts working. Therefore, there is no way that they know what is wrong. One thing that I noticed is that whenever the heater stops working, the green light on the furnace controller (one in the furnace) is blinking and the heater light on the inside temp controller is on. The service tech. told me that blinking light is normal because the controller resets every hour (doesn't make sense to me). I checked most of the connections and they are OK. Can anybody give me some advise?

 

WHATS HAPPENING IS , THERE IS SOMETHING WRONG , AND ITS GOING IN TO LOCKOUT, WHEN YOU TURN OFF THE MAIN POWER YOUR RESETTING IT. I'M NOT FAMILURE WITH THE LENNOX, BUT NEXT TIME, SEE IF THE LIGHT IS FLASHING A CODE. WATCH IT FOR ABOUT 1 MIN... THEN TRY TURNING JUST THE THERMOSTAT DOWN FOR ONE MINUTE AND THEN BACK ON. THERE IS A SERIES OF EVENTS THAT HAS TO TAKE PLACE, IF ONE FAILS THEN IT WILL LOCK OUT. TRY SITTING IN FRONT OF THE FURNACE WHEN IT COMES ON, CHECK REAL CLOSELY, DOES IT HAVE AN INDUCTION MOTOR THAT COMES ON FOR 45 SECONDS, THEN DOES THE HOT SURFACE IGNITOR COME ON.... WATCH AND TAKE NOTE OF ALL THIS. IF ITS A PLUS 90, IS THE CONDENSATE DRAINING?
GOOD LUCK
BOB
MOYER'S HEATING & AIR

 

Hi:jamesml

You now have two problems. One with the heater and one with the service agency.

Your service person isn't suppose to reset the furnace by turning the main power off and then on again. <Anyone can do that.>

What they are suppose to do is locate the the part that caused the interruption from the failure code.

Based on the information you provided:

What they have done is nothing more then what you were doing prior to calling for service.

They made a service call without checking anything. They need to use the diagnostic equipment to locate the failure. Something you will not be able to do sitting in front of the heater looking at the cycling events nor watching any lights flashing & blinking.

<Althought it is cute, I suspect you have better things to do to pass the time of day...hahaha>

Contact them back. Your need to request/demand they fix the problem you already paid them once to do correctly.

Regards,
TomBartco

------------------
Sincerely,
TomBartco
TomBartco Enterprises.
Trade:Natural Gas Energy Consultant & Technician.
Appliance Service & Repairs Rep.
Vocations:Saw & Tool Sharpening. Small Engine Repairs.
Accurate Power Equipment Company.

Personal Quote:
"Drive Safely. The Life You Save, May Be Your Own."

 

EXCUSE ME! MR TOM, THAT IS A GAS TECH? I GUESS YOU HAVE NO CLUE AS TO WHATS GOING ON IN THE WORLD EITHER. AS TO A LOCKOUT IT IS IMPORTANT TO SEE WHAT THE SEQUNCE OF EVENTS ARE . YOU SEE AS EACH EVENT TAKES PLACE, ( IN CASE YOU FORGOT YOUR LESSION ON TROUBLESHOOTING) IT LETS THE CONTROL BOX KNOW THAT THAT EVENT HAS TAKEN PLACE AND ITS OK FOR THE NEXT EVENT TO HAPPEN. WHERE AS WHEN ONE EVENT FAILS, A LOCKOUT IN THE CONTROL BOX TAKES PLACE. NOW, IF THE FAULT LIGHT BLINKS OUT A CODE, DUH! THAT WOULD GIVE A TECH A GOOD IDEA AS TO WHATS WRONG... YES HE DOES HAVE A PROBLEM WITH HIS SERVICE COMPANY, BUT THEN WITH ALL THE DIFFERANT MAKERS OF EQUIPMENT ON THE MARKET, AND ALL THE FAST CHANGES, I CAN SEE WHY... MAYBE ITS BETTER, FOR THEM TO CALL A LENNOX DEALER, LEAVE THE GAS TO THE GAS COMPANY.

 

Thanks for replying for my mail. I have thought that the controller was a problem. You are correct for saying that something lockups the controller. When the Lennox dealer serviceman came, he checked my furnace with his diagnostic testing unit and found that nothing was wrong.

This morning it did not start again When I turned it off and on, it started to work again by seemingly going through all the steps that you mentioned. My furnace controller did not have any other signal than the blinking light. Therefore, it does not tell anything. If I turns off and on my room temperature controller, it stops again within a few hours.

Anyhow, I cannot blame the dealer because I know that this kind of problem is not easy to fix. I am hoping that I can stumble into the solution with you guys' help or the system stop completely.

I am an engineer myself, I can fix most of everything around the house, but this problem is baffling me.

James

 

Lets see if I have this correct.

jamesml:

Your telling us that the service tech did in fact us his diagnostic testing unit and found nothing wrong????

Then can you tell me how come you still have the same problem? How can the unit be fixed if there isn't anything wrong?

In your own words you state the blinking light tells you nothing. Your correct on that one. The light tells nothing about the problem. Then how can you find the problem and fix it watching the light???

In my opinion, your furnace still wasn't fixed correctly based on your statements in your last posting. In my opinion, your wasting your time thinking your going to stumble on to the problem.

I suggest you contact the Lennox factory directly with the problem and let them decide what's wrong and whom to send to correct it. Obviously, your heating rep. hasn't got a clue.

R-12 Dude:

In case you missed it...this is a Lennox GAS FURNACE. Jamesml said so in the first sentence in his first posting.

Therefore, it does take a GAS TECH <like myself> who just happens to have passed both basic and advanced lessons in trouble shooting. And also happens to know that most in the general public who post questions in this forum will not be able to fix problems with modern complex electronic furnaces.

Using your well intentional replies to Jameml, kindly explain to everyone how Jamesml is going to find anything wrong with the furnace, if he doesn't first know what to check, have the diagnosic tools, training and skills to analyze the problem and attempt a correction?

Watching the sequencing of the furnace and the lights isn't going to tell him anything that the homeowner can diagnose, let alone correct.

LASTLY:
I totally resent your statement claiming I haven't got a clue about what's going on in the world. Who in the HELL do you think you are??? And what in HELL does that comment have to do with Jamesml's furnace problem???

I highly suggest you keep your personal and derogatory comments about me or anyone else in this forum and on this site to yourself!

By the way, two points here:

#1
In case you have forgot or haven't checked lately, there isn't any moderator for this forum. Unless you elected to appoint yourself. Have you???

#2
The objective on this web site is to HELP others. This is an open forum that welcomes everyone and anyone who posts alternate views and not a place to post their personal comments regarding others.

Have I made my point clear?
I certainly hope so.

Sincerely,
TomBartco


------------------
Sincerely,
TomBartco
TomBartco Enterprises.
Trade:Natural Gas Energy Consultant & Technician.
Appliance Service & Repairs Rep.
Vocations:Saw & Tool Sharpening. Small Engine Repairs.
Accurate Power Equipment Company.

Personal Quote:
"Drive Safely. The Life You Save, May Be Your Own."

 

ok back to the lights, is this a hot surface ignition system or spark to pilot? now in my experance, there is a light on some of theses units, and if its on constant, it means that there is something with in the control module that is malfunctioning. if it flashes, its a good indication that the problem is out side the control module.
this is called a diagnostic indicator light, most controllers have these now. as far as the furnace, the brands i use all seam to have built in diagnostics and fault codes display, and Guess what? its done all by a little flashing lite.
so that damn little light is important, now do you have a hot surface ignition or a spark to pilot system.

Tom
I was going to get nasty here, but didnt want to stoop down to your level, my only intent here is to help people. and who knows, we just might get this thing fixed using the damn little light. have i made my point clear!

Bob

 

Bob,

It is spark plug ignition system. I know it because service tech who visited last time told me that he cleaned the spark plug.

There is another clue. Sometimes, furnace starts and run about 10 minutes and turns off.

Tom may be right for saying that I am wasting my time to try to figure out this problem. I already tried the Lennox dealer (who installed my furnace 7 years ago.) and they could not find the problem. I am sure that the dealer can fix it if my furnace is finally down consistantly. Furthermore, I would rather waste my time than wasting my money. It is not even wasting of my time, because I enjoy the challenge.

Bob, you already helped me to get a better understanding of system.

Sincerely,

James

 

Jim, lets educate you a little more, upon a call for heat, 25 volts are sent through the safety switches to the ignition module. module then sends power to open the pilot portion of the gas valve and , at the same time, sends 15,000 volts to the ignitor to initiate spark. when the pilot flame has been estabished, a microamp signal is sent back to the module, which terminates pilot spark and switches voltage to open the main burner section of the gas valve. as long as the pilot is lit, micro amp signal to module keeps gas valve open and burner on, when thermostat is satisfied, 25 volts to module is terminated, shutting off gas to both burner and pilot.

now, if all the grounds and connections are good, you 'll have to dig deeper, i would make sure the flame prover is in good flame pattern of the pilot, and the its not cracked , what i would do is take emory cloth or fine sand paper and rub the metal part that is in the flame, if this stops your problem for a while, get a new flame prover and install it.

 

Hi,

I have the same furnace with the same problem. I could start the furnace only by turning it off at the wall switch, waiting a few seconds and turning it back on again. It would be fine for sometimes a week but recently the up time is less and less. I called the service people and they first thought it was an imbalance in the pressure switch which they cleaner/serviced. The furnace seemed OK for the rest of the day. The next morning however it did not come on. Service came back and changed the flame prover. I'll see if this fixes it.

Did you get "closure" on your problem yet?

Thanks,

John

 

Wow, this is an ooooooold post. I had a similar problem too. I got lucky; the flame sensor was dirty. A tiny square of sandpaper is all it took to fix. Much better than a $150 service call.

 

James,

For your consideration:

You describe "resetting" the circuit breaker for this heater and I assume you refer to the circuit in the main breaker panel, not a RESET breaker on the furnace itself. Is that correct?

If that is the case, your problem may be a worn out circuit breaker, especially if this breaker is operating at or near capacity regularly. Is the furnace the only appliance powered by this circuit? Or, have other electrical items been slipped in on the same circuit?

Worn out circuit breakers often work when power demand on the total grid is low and voltage is robust, but fail when demand is high, voltage drops and breaker temps rise. Such cycles occur when everybody comes home from work, when people rise
and shine, when it is very cold, etc. Are the furnace failures occurring at these types of times, or do they occur every time it is started?

A new circuit breaker of the same capacity might be the answer. DO NOT USE A HIGHER AMP BREAKER!

If you attempt to change one, be sure to shut down the main power into the panel first.

Then throw out the old breaker after you change it.

Good luck,

John

 

Ummmm. Well, it's probably a hot surface ignition system. They have ignition sensors that often need cleaning.


When the furnace lights up, you will probably see the white hot glow of the hot surface ignitor develope.


Intermittent problems are the bain of repairman.


If you can't identify a cause for such problems, the first thing to do is to do an excellent job of doing all the maintenance work needed and inspecting for any little defects.

Cleaning the flame sensor would be one of those maintenance tasks. Another thing is to check the pressure switch system for defects.

The problem isounds like it's quite subtle. You probably need to call the repairman back to check it out further.

 

I have the similar problem and I would like to pose additional question:

My Lenex 3-jet gas burner furnace stopped working (was found to be short-cycling) yesterday but by (1) shutting off the power to the electronics of the furnace -OR- (2) turning the thermostat temperature to real low and back up to real high with heater on -OR- (3) by leaving the thermostat at 80degF and turning the HEATER switch off and on, a new short-cycle was initiated and furnace started to work ok.

During the forced short-cycling event, I was able to verify that glow igniter comes on and when all three of the jet becomes lit, even though the flame sensor is exposed to proper looking flame, the gas would shut off and another short-cycle event would occur. After two more short-cycle event that result in flame sensor mal-functioning, the furnace would wait probably for one hour before next three short-cycle event is initiated. I didn't wait an hour but force-initiated the three short-cycle event by using one of three methods stated above.

While watching the short-cycling event, I blew on the flame that was heating the flame sensor and this supplied more oxygen(?) and changed the color of the flame and furnace worked ok. I also tapped on the flame sensor (probably cleaned it or delivered a needed mechanical shock to make it operate properly) with a plastic pen.

The furnace did not go through any more short-cycling for about 24-hours now and operates faultlessly (the temperature outside is -3degF today!) and my question is: Did I inadvertantly clean the flame sensor and everything is ok for now and for another 6-7 years or is the flame sensor a trouble waiting to resurface in a couple of days regardless of how much cleaning is done to it? In another words, is the flame sensor's failure mode depend heavily on the cleanlyness of the sensor rod or an intermittent flame sensor is a definite precursor to a permanantly bad flame sensor?

 

Please don't piggyback on another thread. It's confusing and can be dangerous to do so.


I'd suggest reposting on a new thread.