Furnace runs sometimes

10:47 ______________________________________________________________________ I have a 15 year old gas furnace with electric igniter that glows red. The controller is a white rogers box, and flashes a single flash (lockout). The furnace (clare bros??) has worked fine for the last 3 years we were in the house, and just this past winter it started acting up. At first, it would run for 20 minutes or so and go into lockout about 1 in 10 cycles. It progressivly got worse about 2 weeks later to the point that it would only complete about 1 in 10 cycles, but it would always start. I read some articles, and cleaned the flame sensor, and blew air through the water exits (to ensure it wasn’t plugged). It ran ok for about 2 weeks, but then progressivly got worse. I repeated the flame sensor cleaning and it was ok for a day or so. Eventually, the problem was so bad that the burner would not even ignite sometimes. So I’d kill power and it may or may not be happy for a while. Now, it will only ignite about 1 in 10 tries, usually after it has been sitting for a while. When it does ignite, it runs for between 30 seconds and 15 minutes. It has only ever displayed the lockout code. I’m not sure what the problem could be, but I’m assuming the sensor is not the problem because it won’t even start most of the time. I’m assuming it is maybe a gas valve issue? I have a gas hot water heater and it works just fine. Any help is greatly appreciated. Thank you so much in advance. Replies: sascache “Re(1):Furnace runs sometimes, but wont always” , posted Fri 20 May 13:37: ______________________________________________________________________ [this message was edited by sascache on Fri 20 May 13:39] niko851 “Re(1):Furnace runs sometimes, but wont always” , posted Fri 20 May 12:09 ______________________________________________________________________ Hi there – I’d start by changing out the flame sensor since you have more/less isolated it via the cleanings… On the other hand, could be coincidence…. Nevertheless, since it (probably) is the original, the cheapest route to start is by changing out the flame sensor. As far as teh lock-out code, depending on what white-rodgers model, that ‘may’ be the only code it will give. Nowadays, there’s more sensors and components so the units self-diagnose alot easier… Give that a shot and let us know.. Also, get the model# off that WR module and I’ll look up the spec’s on it… Hope this helps, Niko Check your circuit breaker or fuses before calling for service – it could save you $$!! sascache “Re(2):Furnace runs sometimes, but wont always” , posted Fri 20 May 13:40 ______________________________________________________________________ I really do appreciate the help…. The # on the white rogers box says:50A50-215. I can try replacing the flame sensor, there must be more to it though since now it only lights 1 in 5 times. Can I get those as the hardware store? There are 6 codes it can flash. They are something like Lockout Open limit closed limit?? Something about sensor wire not plugged in and 2 others that are escaping me right now (pressure switch??) Thanks a ton! Skippy “Re(3):Furnace runs sometimes, but wont always” , posted Fri 20 May 23:16 ______________________________________________________________________ Hi! It sounds like the ignition control module is packing it in. Is the ignitor glowing every time but just no gas? Check for 24vac at the gas valve when the ignitor comes on. If no, or lower than 24 volts then locate the transformer and check at the transformer output leads. Should be between 24-28 volts. If you have less than 24 volts, replace the transformer. If 24 or higher, replace the module. Skippy Work smarter not harder! niko851 “Re(3):Furnace runs sometimes, but wont always” , posted Fri 20 May 20:30 ______________________________________________________________________ Hey Xenos/Original poster – It appears and is affirmed in the post that actual igntion sequences are occurring. I (assumed) that the Poster was veering in the direction that either he got ignition, got ignition and subsequent lock-out, or he was simply in lock-out. I concur that it may be an igntion issue; however, given the nature of the post, it appears that the unit cannot even make it to the ignition sequence due to the lock-out; again, this is the only code ever referenced and not another code. Since there is no pressure code, limit code, or any other code, I’m only speculating that the ‘lock-out’ code is the only applicable code for flame failures and/or failure to ignite. The post also stated that the unit would run for some time, but then lock-out. He stated that it runs anywhere between 30 seconds to 15 minutes at times. So I’m just not convinced that there’s a problem with the ignition portion and/or sequence, given that he does get an ignition, granted not as he should. No intent to dispute and/or debate, but my opinion & suggestion of replacing the flame sensor will either prove or disprove our theories. From past experiences on a ‘lock-out’, that tells me that (without using extreme technical terms for the sake of the poster) once the flame is no longer sensed, the lock-out occurs. On teh contrary, there should be retries; I am unable to form a belief as to this aspect for the lack of knowledge in this respect. Thus, I must continue to speculate that it could be a sensing issue, rather than an ignition issue, as the unit does fire. As I’m sure you know, once that voltage or signal is no longer present, the burners are going to shut down and possibly lock-out, just as indicated. Again, no intent whatsoever to argue/debate here… Only trying to use my brain to the best i can and advise with my opinion. Let me know what you think Xenos – I’m always open to discussion as it is only beneficial for all of us in here :) Niko Check your circuit breaker or fuses before calling for service – it could save you $$!! Xenos Webmaster “Re(3):Furnace runs sometimes, but wont always” , posted Fri 20 May 19:15 ______________________________________________________________________ If it only fires 1 in 6 times is sounds more like an ignition problem other than a sensing problem. Xenos. The best way to escape a problem is to solve it. niko851 “Re(4):Furnace runs sometimes, but wont always” , posted Fri 20 May 20:30 ______________________________________________________________________ Hey Xenos/Original poster – It appears and is affirmed in the post that actual igntion sequences are occurring. I (assumed) that the Poster was veering in the direction that either he got ignition, got ignition and subsequent lock-out, or he was simply in lock-out. I concur that it may be an igntion issue; however, given the nature of the post, it appears that the unit cannot even make it to the ignition sequence due to the lock-out; again, this is the only code ever referenced and not another code. Since there is no pressure code, limit code, or any other code, I’m only speculating that the ‘lock-out’ code is the only applicable code for flame failures and/or failure to ignite. The post also stated that the unit would run for some time, but then lock-out. He stated that it runs anywhere between 30 seconds to 15 minutes at times. So I’m just not convinced that there’s a problem with the ignition portion and/or sequence, given that he does get an ignition, granted not as he should. No intent to dispute and/or debate, but my opinion & suggestion of replacing the flame sensor will either prove or disprove our theories. From past experiences on a ‘lock-out’, that tells me that (without using extreme technical terms for the sake of the poster) once the flame is no longer sensed, the lock-out occurs. On teh contrary, there should be retries; I am unable to form a belief as to this aspect for the lack of knowledge in this respect. Thus, I must continue to speculate that it could be a sensing issue, rather than an ignition issue, as the unit does fire. As I’m sure you know, once that voltage or signal is no longer present, the burners are going to shut down and possibly lock-out, just as indicated. Again, no intent whatsoever to argue/debate here… Only trying to use my brain to the best i can and advise with my opinion. Let me know what you think Xenos – I’m always open to discussion as it is only beneficial for all of us in here :) Niko Check your circuit breaker or fuses before calling for service – it could save you $$!! Xenos Webmaster “Re(5):Furnace runs sometimes, but wont always” , posted Fri 20 May 20:37 ______________________________________________________________________ I just concentrated on one line and I may have used the term ignition in the wrong tense. Yes we know the igniter is operating however I am not sure if the gas is igniting every time. Xenos. The best way to escape a problem is to solve it. niko851 “Re(6):Furnace runs sometimes, but wont always” , posted Sat 21 May 09:37 ______________________________________________________________________ Got ya…. Makes sense now – guess I read to quickly eh?? :) So if we use your theory, which is quite plausable, then he’d need to see if he’s getting a glow (or spark) and pilot before main ignition. The lock-out makes further sense in this respect as regardless, no glow or no ignition, the lock-out is going to happen… Now it is up to the Homeowner to do some more ‘testing’ via calls for heat to see if A) glow-coil comes on; B) If not, then we need to know if it has already locked-out or if the igniter is simply not coming on; C) If yes, then need to verify that pilot lights and subsequent main gas valve opens. The kicker is, when it does fire, and kicks out within the 30 sec – 5 minute time-frame, I still veer towards the sensor. Then again, if there’s an issue (as you’ve stated) with obtaining ignition, there’s the ‘other’ kicker… What I’d do to go to this guy’s house just to see for myself – LOLOL…. Niko Check your circuit breaker or fuses before calling for service – it could save you $$!! liquid “Re(3):Furnace runs sometimes, but wont always” , posted Fri 20 May 15:39 ______________________________________________________________________ start from the top turn off power to furnace, check air filter, dirty? replace it. power up, not knowing components on your furnace, but heres a shot, vent motor should turn on first, actavates pressure switch, signals to board 50a50 to energize the ignitor, the brite orange stick, after aprox 11 sec to 17 sec gas vavle should open main valve to get gas to the manafold to burners, which than the ignitor ignite the gas, all burners light up, last burner should have the flame sensor in front of it , sensor sends signal to board to stay on only if flame is on sensor. than gas heats up the heat exchanger, either by timer or fan/limit control the blower fan kicks on. have a nice day sascache “Re(4):Furnace runs sometimes, but wont always” , posted Mon 23 May 12:51 ______________________________________________________________________ Thanks for all the informative posts. I see the igniter stick glow red for every single ignition sequence. Most of the time, it will glow red for 5 seconds….I hear a click (assuming relay to turn gas on?) then it usually waits 5 more seconds and I hear a click again and the igniter stops glowing (no flame to be seen anywhere) If it has been sitting for a while (like an hour) it will usually start up and run for about 30 seconds to 15 minutes. But once it has been running, it doesn’t want to start again. Thanks again! Xenos Webmaster “Re(5):Furnace runs sometimes, but wont always” , posted Mon 23 May 13:13 ______________________________________________________________________ It’s sounding more like the gas valve. Xenos. The best way to escape a problem is to solve it. sascache “Re(6):Furnace runs sometimes, but wont always” , posted Mon 23 May 14:58 ______________________________________________________________________ You guys are great, can anyone tell me how to test 24v on the gas valve? It has 2 orange wires going to the top of the valve. They both say MV where they hook up to the white rogers box. There is also a green wire at the bottom that goes to ground on the rogers box. I tried using my multimeter in parallel with one end on an orange line, and the other end on the ground. This kills the flame when I touch it.(its working because it is 76 degrees and hasn’t run for a while) The other orange wire doesn’t seem to have voltage. And when I check voltage accross the 2 orange MV wires (in parallel) it kills the flame. Am I doing something wrong? Thanks! Xenos Webmaster “Re(7):Furnace runs sometimes, but wont always” , posted Mon 23 May 15:07 ______________________________________________________________________ You should see 24vac across the 2 gas valve wires when you hear the click. Xenos. The best way to escape a problem is to solve it. sascache “Re(8):Furnace runs sometimes, but wont always” , posted Mon 23 May 15:37 ______________________________________________________________________ So should I put the 2 ends in parallel with the gas valve? I put the 2 ends on this way after the flame was lit and it caused the flame to go out both times that I tried it. If I test it with the leads on the contacts before flame, it won’t start. I’m checking voltage across both orange lines….not against ground, correct? If so, how come it kills the flame/won’t let it start? Any ideas? thanks again so much for the help! Xenos Webmaster “Re(9):Furnace runs sometimes, but wont always” , posted Mon 23 May 16:06 ______________________________________________________________________ I have no idea how this is causing a problem if your meter is on the voltage scale. Xenos. The best way to escape a problem is to solve it. sascache “Re(10):Furnace runs sometimes, but wont alway” , posted Mon 23 May 16:32 ______________________________________________________________________ I tried again. It is on V AC and I don’t even see the # change off of 00.0 when the the valve should be opening. I’m crossing it between the 2 orange wires, not touching the ground wire and it won’t start. It starts when I take the multimeter away (works ok when it is cold) Thanks a lot for the help, I may have to call someone in, just thought that if I had an idea of what it was I could possibly do it myself. niko851 “Re(2):Re(10):Furnace runs sometimes, but wont” , posted Tue 24 May 09:04 ______________________________________________________________________ I must say that Xenos’ speculation was correct… Appears that you’ve got some issues w/the gas valve, not with the flame sensor as I previously thought. Given the complexity of the situation, or unless you’ve got a bad meter/wrong setting – well, let’s just say calling for service is probably your best bet at this point… There’s just wayyyy to many variables and they just keep on racking up.. I know it’s not funny nor is it helping the situation, but there’ something VERY weird going on w/that unit and from a reading standpoint, it’s hard to tell what you’ve got going on now…. Also, you may run into an issue of purchasing the gas valve – possibly. In Mich, you have to be licensed to purchase them now. Guess too many peoples’ homes were blowing up due to improper installations. Niko Check your circuit breaker or fuses before calling for service – it could save you $$!! Gasmaster “Re(3):Re(10):Furnace runs sometimes, but wont” , posted Mon 11 Jun 22:20 ______________________________________________________________________ Hi This may have been mentioned already but, has anyone checked polarity (or phasing) yet? 120 volt hot to 24 volt hot should read in the ballpark of 94 vac, not 145-154 vac. I have found ignition modules may work fine when new but, after a few years they can create nuisance lockouts if polarity is reversed. I have seen very erratic problems from this condition over the years. If you find polarity reversed, reverse the transformer primary wires (120 vac side) and recheck the voltage, you should see approx. 94 vac…..

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