Gas furnace goes off excessive gas flow?

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  #1  
Old 02-08-18, 12:00 AM
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Gas furnace goes off excessive gas flow?

Hi Folks, I am facing quite new and unusual (for the HVAC pros in my area) issue: my gas furnace won't stay lit unless I adjust the gas flow control arm on the main pipe that goes in the furnace. Once lowered, it is working quite steadily and does not go off.

Any suggestions on WHY is this happening and how to fix it (need it running @ its fullest, huh:?), would be highly appreciated!
 
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  #2  
Old 02-08-18, 03:47 AM
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A better explanation is needed. What is the gas flow control arm and what does it look like and do?. What is the age of the furnace and make and model number. Pictures would be helpful
 
  #3  
Old 02-08-18, 06:20 AM
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What is shutting the furnace off?
The manual gas shutoff valve is NOT a throttle.
 
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Old 02-08-18, 03:27 PM
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Hi, thanks a million for your prompt response(s). The gauge, the arm is on the pic. The furnace is 15 yo, Carrier. Cheers, V
 
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Last edited by Vlado; 02-08-18 at 05:27 PM.
  #5  
Old 02-08-18, 05:29 PM
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When the manual gas shutoff is semi-opened, the furnace works okay. Once fully opened, excessive gas overflows the burner?
 
  #6  
Old 02-08-18, 05:36 PM
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Welcome to the forums.

That IS a problem and would suggest a defective gas valve.... in particularly the regulator stages. If you have a technician.... have him check the manifold gas pressure. If you don't have a tech..... check with your gas supplier. They employ some good field technicians and will take care of the problem without gouging or trying to sell you a new furnace.... unless it's absolutely necessary.

That MUST be addressed as soon as possible.
 
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Old 02-09-18, 03:56 AM
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Running the furnace like that is potentially dangerous, and can cause damage to the furnace. It must be fixed ASAP.
Closing that valve down like that is not a fix.
 
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Old 02-09-18, 12:16 PM
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Guys, many thanks for your kind responses and direction, much appreciated. Where can you see the danger in semi-shut gauge?
 
  #9  
Old 02-09-18, 03:21 PM
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Improper gas flow/pressure/volume.
Improper use of that valve. It isn’t designed to be a throttle or operate in a mid position like that.
 
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Old 02-10-18, 05:05 PM
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So I guess the question is still there... Anyone with any ideas of what is causing this? Thanks!
 
  #11  
Old 02-10-18, 06:59 PM
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You need to start by
Taking gas pressure readings on the input and manifold side of the valve.
Measure temperature rise across the heat exchanger.
 
  #12  
Old 02-10-18, 07:06 PM
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Sure. It is a malfunctioning pressure regulator incorporated in the combination gas valve. It MAY be simply in need of adjustment if it has always been this way or it may need to have the combination gas valve replaced and the pressure regulator properly adjusted. Generally speaking this is NOT a DIY job.
 
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Old 02-13-18, 04:26 AM
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Any updates here? Get it fixed up?
 
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Old 02-13-18, 09:52 AM
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Guys, many thanks for your contribution and all of the advices! I am in the process of fixing it and will keep you appraised once finished. Cheers, Vlad
 
  #15  
Old 02-16-18, 03:05 PM
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Guys, a quick update on the issue. The Christin HVAC, Inc. rep came to fix it, measured the gas pressure, adjusted it just a little bit and said it should be alright now. Not! The problem is still there, and once he realized that it's something else, he said it is thermocouple, which need to be replaced. Asked for $311 on top of $187 that I already paid... Asked him how likely is that the thermocouple is causing this, given that it has been replaced a month ago and the problem is still there... So $187 wasted, thinking of suing these idiots for guesstimating and making 3 holes in furnace... Cheers!
 
  #16  
Old 02-16-18, 05:06 PM
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That does not seem to have the symptoms of a thermocouple problem.
What was the gas pressure and what did he adjust it to?
 
  #17  
Old 02-17-18, 09:24 AM
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V,
The job of the thermocouple is to tell the gas valve it's OK to open. It has nothing to do with regulating gas pressure.

As PJ suggested that is the job of the gas valve which has a regulator built in.

If the thermocouple was your problem by not sensing the heat to open the gas valve you would have no fire at all.

Unless I'm missing something I can't understand why they keep looking at the thermocouple and not taking gas pressures and look at the gas valve.

Just my thoughts, hope this helps a little.
 
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Old 02-19-18, 07:40 PM
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Guys, thanks a lot for all of your responses. Please see the pic. The MF drilled three holes in the system for no reason! Is that too bad for the furnace? New concern now
 
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  #19  
Old 02-20-18, 02:10 PM
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The hole in the smoke pipe for the combustion test is normal.
 
  #20  
Old 02-21-18, 05:20 PM
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I thought the other service guy checked gas pressure and said it was ok? 4.06 is much too high.
 
  #21  
Old 02-27-18, 05:54 PM
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Hi Folks,

Just posted an update and it disappeared from this thread. In a few words, this was the same guy, who adjusted the pressure, drilled 3 holes and left, telling me it was all bad thermocouple. He said, the diameter of the pipe in the couple was not right. Do you think the thermocouple's bandwidth may be an issue? Thanks a lot. I think they just sucked my money and showed their back.
 
  #22  
Old 02-27-18, 06:36 PM
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To repeat what was said earlier in this thread, the thermocouple has nothing to do with gas pressure.
Why did he drill holes in the flue pipe? To test the combustion gasses?
Is the unit still functioning properly? Is the gas valve open fully?
 
  #23  
Old 02-27-18, 07:44 PM
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I have no idea of WHY he drilled the hole he never asked, and when I realized that, it was too late suing these mfs. The problem is still there, and the gas valve is open on 2/3s. thank you!
 
  #24  
Old 02-27-18, 07:55 PM
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I’d call another company to take a look. Or call the service manager and complain.
Either way it still needs to be addressed ASAP.
 
  #25  
Old 02-28-18, 08:43 PM
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Hi Roughneck77, thank you called and complained the same day, spoke with the manager. He told me that I paid $99 just for the visit and diagnostics, and although incorrect, and the problem persists, they adjusted the valve for an extra $88. Rip-off. Any suggestions? Before I take them to court, need your words of wisdom and advice. Thanks
 
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