York gas furnace will not stay lit

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Old 02-22-11, 11:05 AM
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York gas furnace will not stay lit

I have a York diamond 90 furnace. When I turn on the furnace, one by one everything turns on. I mean the intake fan goes on, the glow light, the gas, the flame, and the circlulating fan. After a about 10-20 seconds, the combustion chamber starts shaking a bit and the flame goes out. Then everything starts over again and the same thing happens. After several tries, the unit locks up and basically turns off. I don't think it is either of the pressure switches, because I do not hear the microswitch click before the flame goes out. The flame looks all blue, except just before it goes out when everything is rattling. The the flame has lots of orange color just before going out. I cleaned off the flame sensor. What else could it be? Could it be the gas valve? What would be the symptoms of an unreliable gas valve?
 
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Old 02-22-11, 11:41 AM
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could be a heat exchanger issue......Doubtful it is the gas valve. Ensure your intake and exhaust pier are clear and open. Check the drain trap assembly and remove and clean if possible. ensure 1/4" per foot slope of flues back to the furnace.
 
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Old 02-22-11, 01:00 PM
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The intake and exhaust seem to be clear. How would I really know? What are the guidelines in setting them up to work properly.

I did find water in the drain trap. I think water was coming in the intake pipe, so I made a U up and down to keep water out. The problem started before I did this. Do I need to clean the drain trap too? I saw junk at the bottom.

You mentioned the heat exchanger. What could be the issue there?
 
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Old 02-22-11, 01:16 PM
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the heat exchanger may have failed........
As far as flues, I'm not following what you did there
I made a U up and down to keep water out
yes, if possible remove trap and clean it out.

Back to flues can you run the furnace with the intake remove from the furnace and if so, how well does it run this way?
 
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Old 02-22-11, 02:23 PM
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I will see if I can remove the intake to see how the system works. I don't think this is easily done.

Since I found a lot of water at the bottom of my York unit, I attempted to make it more difficult for water to get in the line. Where the old intake line comes into the house, I added a section that goes up a couple of feet and down about a foot to the new inlet. In other words, water would have to go up a foot into the pipe to get into my furnace.
 
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Old 02-22-11, 02:34 PM
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you should never do this........if you are getting water in through the intake there are other solutions that can be done outside
 
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Old 02-22-11, 05:00 PM
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What other ways can I keep water out of the inlet? Everything I did is reversible.

Please tell me more about a possible heat exchanger failure.
 
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Old 02-22-11, 06:57 PM
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Heat exchanger failure is a crack or hole in the heat exchanger, and needs to be checked over by a professional.
as far as intake flue termination, i need more information about your current termination. Is it side wall vented or roof vented.

Every elbow you add to your flue adds 5 feet of length to the total flue length. Furnaces are specified for certain lengths depending on size of the flue. This information can be found in the installers guide for your furnace.
 
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Old 02-22-11, 07:33 PM
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It really does sound like a heat exchanger problem would need a professional.

You have me thinking the flue is the problem. My flue is side wall vented. I did not really understand what you meant by each elbow adds 5 feet. I better check out the installation manual.
 
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Old 02-22-11, 08:12 PM
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You can click on this picture to make it bigger. It is an example of flue terminations. It is not specific to your furnace but gives you an idea of options of terminations. The main thing you will notice is that on the intake it has elbows that make it so no water can drop into the intake pipe.




Your furnace has a specified flue length that can be run before you will have problems. Each elbow adds 5' length to the total amount of flue length. 10' horizontal run and 5' vertical run with 2 90 degree elbows has a total flue length of 25'
 
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Old 02-23-11, 09:02 AM
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Do you really think my problem is a flue problem? The flame looks completely blue when it lights. Just before the flame goes out, the color has more orange and the whole firebox vibrates. What would cause the vibration? Sometimes the vibration seems to put out the flame and sometimes it does not. The vibration seems to come and go.

Your help is greatly appreciated.
 
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Old 02-23-11, 09:32 AM
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Yes, it does sound like a problem with the system that provides combustion air for the furnace.

You should use an AC voltmeter to check and see if the pressure switch is opening and shutting off the furnace, which it probably is.


The change in color of the flames, the shuddering in the heat exchanger and the excessive water you are finding all suggest those kinds of problems, and suggest in particular that the furnace drain system is plugged up in some way and causing the problem.

Your modifications of the drain system in particular are probably ill advised.

When natural gas burns, the hydrogen in the gas burns to water vapor, and a 90% efficient furnace like yours condenses the water vapor into liquid water. That can amount to a gallon of condensate an hour were the furnace to run continuously.

If that isn;t free to drain away, it will plug up the furnace preventing the inducer fan from running properly and plugging up the ventilation system that provides fresh air for the gas to burn. That will produce soot and carbon monoxide.


It sounds like you are having problems with that drain system. But this is not a place for DIY experimentation, which can create real hazards. You would probably be wise to have a good repairman come in to analyze the problem and correct it.
 
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Old 02-23-11, 02:47 PM
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I concur with SeattlePioneer.
 
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Old 02-25-11, 08:35 AM
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I did call a pro. He found a broken gas valve. The part needs to be ordered.
 
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Old 02-26-11, 09:32 PM
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The pro came over and changed the gas valve. The furnace works a bit better, but the flame still goes out sometimes. Every so often a draft seems to come into the firebox and put out the flame. I read this could be a cracked firebox. A firebox has negative pressure caused by the inducer. The circulating fan outside the firebox has positive pressure. If there is a crack, air could push through the crack and put out the flame. Could that explain this problem? How would I determine whether there is a crack?
 
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Old 02-27-11, 01:51 AM
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A c racked heat exchanger could be an explanation for your problem. You really need to determine what is shutting off the burners. That could be the limit switch, pressure switch or something else.

Checking for a cracked heat exchanger takes a careful inspection of all the surface of the heat exchanger and knowing what to look for. It's really not a DIY job, it takes experience to do such an inspection reliably.


I'd start by identifying what is shutting off the burners. Guessing that there is a crack is not the place to start.
 
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Old 02-27-11, 06:17 AM
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get your pro back out there, if its still not fixed then he missed diagnosed!!!!

again same as Seattle said, we need to find out what is causing the burners to drop out. We need to do some diag work with a volt meter and determine the cause instead of guessing. A good pro would have looked over the whole system not just the problem you were having, which I feel he did neither, but I wasn't there so I don't know what he did or did not do.
 
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Old 02-27-11, 09:22 AM
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My problem is that each call costs at least $200. Coming to diagnose the gas valve and returning to replace it, together cost close to $500. All these HVAC people want to do is put in a new system or sell a cleaning service. I feel like I am paying for a commercial. Who will tell me the truth. How do I know when I do need a new system? My system is about 13 years old. It has needed much more service than my oldest system. Any suggestions would be greatly appreciated.
 
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Old 02-27-11, 11:05 AM
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you miss understand, hold the HVAC company responsible for misdiagnosing your problem. The repair was made and the problem still existed. If they are a good company then they will stand behind their work. It cost less to keep an existing customer than it does to get a new one.
 
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Old 02-28-11, 07:21 AM
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I really am not misunderstanding you. I do not want to throw money down the drain. If I can help troubleshoot the problem, then I will. Most of the time I have found people on the Internet very nice and helpful.
 
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Old 03-09-11, 08:41 PM
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It has been a couple of weeks since my last post and I wanted to give an update of my progress. My York Diamond 90 is working better than it has ever. It turns out that my exhaust was installed too close to my intake. I tried an experiment by laying a wood board between the exhaust and intake. The results were quick.
 
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Old 03-09-11, 10:45 PM
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It's true that having the exhaust and air intake too close will cause combustion gasses with no oxygen to mix with combustion air, causing too little air for the gas to burn properly.

If that were the problem I would normally be expecting you to report this was happening with a new furnace. It's not the kind of thing I'd expect to simply start on a furnace that has been operating normally for some considerable period of time.

Also, do you have the installation manual, and did you compare the venting standards described there with what you have?

IF the equipment is installed as specified by the manufacturer, I would expect it to operate properly.

I reviewed the history of posts on this thread and I didn't see anything which would have suggested your fix, even in hindsight.

I'm glad you found a fix of course. But repairing equipment isn't normally predicated on wild intuitive leaps or guesses, but a logical process of identifying possible problems and eliminating possible causes one by one.

So based on the thread, I can't really understand how you got to the solution you came up with. It's a mystery to me.
 
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