Ask Me Help Desk - Bryant 355MAV error 34 & 14 Ignition Lockout

Hi everyone,

I own a Bryant 355MAV furnace which has been installed since Autumn 2001 and run without trouble since then (except a minor airflow issue last winter which was helpfully solved here in this forum).

I've been running the heater for most mornings since early October without issue. However, a couple of days ago, when I turned it on first thing in the morning it never began blowing hot air. After a number of tests here is everything I have been able to learn about the problem --

The unit turns on, but encounters error code 34, Ignition proving Fault, which after a few minutes leads to error 14, Ignition Lockout.

When I turn the unit on from the thermostat, the inducer motor comes on for about 20 seconds or so. Then I can see the hot surface ignitor glow brightly through the burner sight glass on the burner assembly. However, after that NO flame ignites in the burners that I can see.

At this point error 34 is tripped. It tries three more times then shuts down completely, and switches to error 14.

I've inspected the furnace according to the instructions on the inside panel for the 34 error. All the components inside the burner assembly, including the ignitor and the flame sensor, are clean and mostly free of oxidization as far as I can tell.

I could smell a faint whiff of natural gas on at least one of the tests during the point where the furnace tries to turn on the gas burners. I have to emphasize that it was very faint, like from a gas stove which takes a second or two to fire. There is NO gas fumes at any other time, such as when the unit is not functioning. The manual gas shut-off valve was on, and the gas lines leading up to and inside the unit all seem unmoved and undamaged.

The green ground wire to the sheet metal is still affixed.

The vent and combustion-air pipes all seem fine, and the vent on my roof is free of obstruction as far as I can tell.

I haven't any work done on natural gas lines to my house (or in the neighborhood), and my other gas appliances have not had any trouble that I know of.

If anyone has any advice or tips about how to determine what the likely problem is, I'd really appreciate it! If I've neglected to mention anything, please ask! Thanks in advance!

If it's helpful, here's the complete text from the inside panel for error 34:

Code:

Ignition proving fault. Control will try three more times before a lockout 14 occurs. Check for gas valve defective or gas valve turned off Defective hot surface ignitor Low inlet gas pressure Manual valve shut-off Flame sensor must be ungrounded Green wire MUST be connected to furnace sheet metal Proper flame sense micro-amps Inadequate flame carry-over or rough ignition Control ground continuity Oxide build-up on flame sensor (clean with fine steel wool)

Try cleaning flame sensor well with steel wool or sandpaper

Try this: remove cover from burner compartment and re-try. If ignition is successful, check for leaky ignitor gasket, or look CLOSELY for webbing (yes, I said webbing) inside far-right burner.

Thanks to both of you for your suggestions. I'll try them all out tomorrow morning when I next have the chance to work on the furnace, then report back. Fingers crossed!

After some delays, I was finally able to get up and test the furnace on two more occasions.

Firstly, I did clean the flame sensor as hvac1000 suggested. It had a minor amount of oxidization. Unfortunately, this didn't do the trick.

Now for KC13's suggestions:

Quote:

Originally Posted by KC13

Try this: remove cover from burner compartment and re-try. If ignition is successful, check for leaky ignitor gasket, or look CLOSELY for webbing (yes, I said webbing) inside far-right burner.

There WAS a small amount of webbing close to the far-right burner, but I couldn't locate any inside it. Nevertheless, I cleaned what webbing I could see around it and tried to clean the far-right burner as best as possible.

Unfortunately, the furnace STILL does not fire either with the burner compartment removed OR not removed.

Note that I can hear what seems to be a faint hiss of natural gas just at the point after the hot surface ignitor lights up, when I assume it's trying to turn on the gas and fire the burners. None of the burners fire, however, and the 34 error is tripped at this point.

I should also point out that there are a few of what looks like little burnt ants on the bottom of the burner compartment (not directly beneath the far-right burner). Only a few. I have no idea what they're doing there or if they are in fact ants. There is no other evidence of ants anywhere else.

My furnace is actually installed suspended on its RIGHT side, in my attic. That means that the "far-right burner" you describe is actually the BOTTOM burner in my installation.

I can smell natural gas faintly in the burning compartment after the attempted fire-up, whether the compartment cover was removed or not.

I examined the ignitor gasket (I believe it's the ignitor gasket -- perhaps you might tell me exactly where it is) and it does not seem damaged or to be leaking in any way.

There are two specific questions at this point:

1. Does the fact that the burners do not fire even with the compartment cover removed suggest something to you?

2. Also, I was a little concerned about cleaning the far-right burner too aggressively. Is there a safe or uncomplicated way to remove the burner from the unit so I can more thoroughly clean it? It's a little cramped "in situ" so I cannot be sure if there isn't in fact some webbing or something inside the burner that I can't see that's causing the problem. It sure seems that way to me!

Thanks very much for trying to help me out!

Sounds to me like you have got low gas pressure, or a bad gas valve.

(These instructions apply to an upflow installation. Turn 90* in appropriate direction for horizontal orientation. Only perform these steps if you are sufficiently qualified.) Turn off power & gas supply, loosen nearest union BETWEEN gas cock & furnace. Remove wires from gas control, noting where each one belongs. Remove cover from burner enclosure & remove 2 screws securing manifold to enclosure. Lift upward/outward to disengage manifold from enclosure & carefully move aside. Remove screws securing burner set, remove burners. Inspect burners for debris in passage and runner slots. Check manifold orifices for blockage (ants?), particularly the one facing burner nearest to ignitor. If debris is present inside burner enclosure, CAREFULLY remove with vacuum cleaner. AVOID ANY CONTACT WITH IGNITOR. Re-install burner set and manifold, assuring that manifold brackets engage correctly in slots AND all orifices engage fully into burner entrance, replace manifold screws. Reconnect wires to gas control, reconnect gas supply & turn gas on. Apply liquid soap to union, check for bubbles (indicates leakage - correct before proceeding). Re-install cover on burner enclosure. Turn on power supply and check unit operation.

Quote:

Originally Posted by Joshdta

sounds to me like you have got low gas presure, or a bad gas valve.

Thanks for answering.

Do you think this would be the case even though the day before the furnace was running fine (and for every day over the previous month)?

Low/no gas pressure was actually the first thing that came to mind when I learned what the error code was. Do you have a suggestion about how I could check for these problems, given that I'm the homeowner and not a furnace expert?

Thanks again.

Quote:

Originally Posted by KC13

(These instructions apply to an upflow installation. Turn 90* in appropriate direction for horizontal orientation.) Turn off power & gas supply, loosen nearest union BETWEEN gas cock & furnace. Remove wires ...

Wow, thank you VERY much for these instructions. I will carefully perform the steps you describe tomorrow morning and then report back to you.

Thanks again!

Pay particular attention when re-installing manifold to assure proper alignment of orifices into burners. Good luck!

Quote:

Originally Posted by KC13

Pay particular attention when re-installing manifold to assure proper alignment of orifices into burners. Good luck!

I got back up in the attic earlier today armed with a printout of your instructions, and when I dismantled the burners I basically instantly discovered the problem: as you first guessed, there was a very thick, fine webbing encasing the rightmost burner jet. This webbing was impossible to see without dismantling the unit and taking out the burners, so thanks to your instructions I was able to find the obstruction.

Sure enough, after carefully cleaning the burner and then carefully reinstalling everything, the furnace fired up!

Oh, the gratification of seeing those blue flames burst to life!

So for anyone else who has these error codes, do follow KC13's advice and instructions to check and then clean the rightmost burner.

I can't thank you enough for taking your time to so carefully help me analyze and then solve my problem, KC13. This is the second winter in a row that you have actually saved my bacon with furnace advice, did you know that? Thanks again!

I could write a book on the unusual and inconceiveable things I encounter in the field. What you experienced, and the detail with which you described it, made it easy for me to recognize the problem. See you next year!

Please, will someone tell me what that webbing is or where it comes from?

"there was a very thick, fine webbing encasing the rightmost burner jet."

Spiders love to make those webs