Trane XB80 2 issues?

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Old 11-16-11, 04:28 PM
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Trane XB80 2 issues?

So I have 2 questions. Ill start with the problem I believe I have resolved. My furnace (trane xb80) displayed error code "thermal protection device open". It would run still, but not for long and shut off the heat, inducer motor would stay on and display the code. I swore the blower motor was running but am not 100% sure and maybe it was only working randomly. Upon inspection of the circuit board I found that the speed tap wire going to "heat H" had came loose and was barely touching the terminal (not connected but touching metal to metal by a nose). I put the wire back on snugly and now I am up and running fine. Could this wire being loose have caused the "thermal protection device open" code? I assume so since the heat possibly was building up due to blower motor not working and causing the high limit switch to open.

Ill explain 2nd question as follows:
Normal call for heat. Inducer motor starts. Igniter glows. Hear hissing of the propane. No ignition. Does this 3 times then displays code "system lockout". It will usually fire up 2nd or 3rd time but occasionally is goin into the lockout and i have to reset. I not knowing any better tried to clean up the igniter with green scour pad. Had professional service man come and he cleaned the burners up for me, we cleaned up the flame sensor with sand paper and checked the igniter. (I noticed the flame sensor has a tiny bit of pitting, or a small tiny "rough" spot. He said the igniter was ok so I assume I didnt damage it. He also didnt seem worried about the flame sensor. What else do I check as to why Im not getting ignition 100% of the time? Everything works fine once it ignites.
Also I notice that the furnace starts up when my temp on the thermostat is at the set temp (thermo set to 70, furnace starts up when the thermo reads 70).
 
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Old 11-16-11, 04:47 PM
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<< I put the wire back on snugly and now I am up and running fine. Could this wire being loose have caused the "thermal protection device open" code? I assume so since the heat possibly was building up due to blower motor not working and causing the high limit switch to open.

>>


Very likely that's the case, based on what your describe.
 
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Old 11-16-11, 11:44 PM
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Thanks seattle. Do you have any suggestions on other things to check as far as to why furnace does not ignite everytime and occaisionally goes into system lockout because not igniting.When it fires up it runs perfectly fine. With everything working correctly most times i dont understand what else there is to check. I realize there are probably other threads similar, but realistically I dont have the time to scour through them ALL. I have 2 infants and heat problems. Just looking for some direction here is all. Thanks.
 
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Old 11-17-11, 01:27 AM
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is furnace cycling on and off every 5-6 minutes normal?

I have a trane furnace XB80. Model # TDE080A945M1. I assume it is 80,000 btu. My house is approx 2100 sq ft 2 story. It is 32 deg outside now and 26 with the windchill. I have a basic honeywell digital thermostat. It CANNOT be programmed to set hi and low temps throughout the day. It only allows me to have 1 set temp. I noticed tonight it is kicking on and running my furnace for approx 5-6 min then off for 5-6 min, then repeats over and over. It has always seemed to turn on and off like this (every 5 min or so) since I bought the house 3 years ago, but this is first time I timed it out through the night. Is this ok? I have the thermostat set for 71 deg and the furnace will kick on even when the thermostat reads at 71 deg. Is this ok and possibly it is just trying to maintain the temp? It isnt having issues keeping house to set temp (71 deg), just alot of cycling and I dont understand why it would call for heat when the thermostat shows the room temp is what I have it set to be at. I am finding mixed opinions with my research.
 

Last edited by ttype86; 11-17-11 at 01:53 AM.
  #5  
Old 11-17-11, 03:52 AM
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What model is the stat?

It cycles while still showing the room temp because it is maintaining that temp. its actually reading 70.5 or so when it kicks on.
 
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Old 11-17-11, 03:55 AM
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If you are on Propane then the burners probably need replaced with stainless steel burners and I would replace the Flame sensor now rather than wait for it to be eaten up by the propane. Flame sensors are cheap, burners can be expensive.
 
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Old 11-17-11, 04:59 AM
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Originally Posted by hvactechfw View Post
What model is the stat?

It cycles while still showing the room temp because it is maintaining that temp. its actually reading 70.5 or so when it kicks on.
Thanks for the reply. I was hoping this was the case. I am having intermittent issues with my furnace and am trying to make sure everything is working correctly. The thermostat model # is T8401C 1015. It is just the basic square NOT RECTANGULAR one. Non programmable. I have read ALOT tonight/today , and am thinking the cycling this often is ok. Would you agree? It is cycling approx 6-7 times per hour.
 
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Old 11-17-11, 05:14 AM
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Originally Posted by hvactechfw View Post
If you are on Propane then the burners probably need replaced with stainless steel burners and I would replace the Flame sensor now rather than wait for it to be eaten up by the propane. Flame sensors are cheap, burners can be expensive.
Thank you for the reply. I will replace the flame sensor. Do you think as long as the igniter is glowing and firing most times that the igniter is fine? Or is this still a potential cause?
Also I notice slight browning color on backside of the circuit board. Not black, but brownish and some of the glue on the board has tiny cracks. The solder all looks ok to me. Its is an area slightly larger than a golf ball towards the middle of the board and a very small area towards the bottom of the board opposite side of the thermostat wires. I just assumed since Im not getting the bad board code that its ok still.
 
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Old 11-17-11, 05:20 AM
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Also wanted to add that the service man took out the burners and cleaned them up for me. They have a real nice blue flame when burning. The service man thought they looked ok still. Those suckers arent cheap! furnace is approx 7-8 years old.
 
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Old 11-17-11, 06:30 AM
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With an 80% furnace you should be cycling 5 times per hour or so.
 

Last edited by hvactechfw; 11-19-11 at 04:03 AM.
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Old 11-17-11, 07:33 AM
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Please describe the color of the ignitor when the gas turns on.


Measure the AC voltage being applied to the ignitor to see if it's at 120 VAC.

How long is the ignitor heating up before the main burner gas turns on?


I would suppose you have a weak ignitor that isn't getting hot enough to light the gas, a circuit board that's not giving sufficient time for the ignitor to get hot or a circuit board that isn't applying the proper voltage to the ignitor. Those are the things I'd check out.
 
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Old 11-17-11, 11:45 AM
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Whats the pressure of the propane gas coming in to the gas valve? Your not the only one who has had this problem. Ive been to 3 or 4 houses this year with the exact same problem. For some reason the gas pressure was lower than it had been previous years.
 
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Old 11-17-11, 12:38 PM
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Originally Posted by SeattlePioneer View Post
Please describe the color of the ignitor when the gas turns on.


Measure the AC voltage being applied to the ignitor to see if it's at 120 VAC.

How long is the ignitor heating up before the main burner gas turns on?
The color of the igniter is bright orange when the gas comes on. It is alot brighter in the center and not as much around the outside and the top.

The only meter I have is cheap and reads only either 110v,220v,277v, and 460v. I tested in the connection for the igniter in the modular connector and it read 110v on my cheap meter when the furnace tried to start. Do I need to get a better meter?

The igniter heats up and glows orange for approx 15-16 seconds before the gas comes on to ignite. I started the count when I first saw a hint of orange on the igniter.

Also, should I worry about the brown spots and tiny cracks in the glue on the back of circuit board?
 

Last edited by ttype86; 11-17-11 at 01:14 PM.
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Old 11-17-11, 12:43 PM
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Originally Posted by ender2272 View Post
Whats the pressure of the propane gas coming in to the gas valve? Your not the only one who has had this problem. Ive been to 3 or 4 houses this year with the exact same problem. For some reason the gas pressure was lower than it had been previous years.
As far as the pressure I have no clue. Are you talking into the house valve itself, or the furnace? Either way I see no guages for pressure readings anywhere. The regulator on the furnace reads:

Max. press. 1/2 psi
24v. 60Hz .36AMP
Reg. 3.3" W.C.
C341551P01
 
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Old 11-17-11, 03:15 PM
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110 VAC is lower than it should be. An orange color ignitor is probably not hot enough to light the gas reliably.

What percentage of the trials for iognition result in the furnace lighting and what percentage result in failures?

You might want to check and see if the voltage is at 120 VAC when the furnace ignites and if the color of the ignitor is a hot incandescent white rather than orange when the furnace lights.

There is no reason you can't turn the furnace on repeatedly in order to check on these issues.
 
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Old 11-17-11, 03:49 PM
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Originally Posted by SeattlePioneer View Post
110 VAC is lower than it should be. An orange color ignitor is probably not hot enough to light the gas reliably.

What percentage of the trials for iognition result in the furnace lighting and what percentage result in failures?

You might want to check and see if the voltage is at 120 VAC when the furnace ignites and if the color of the ignitor is a hot incandescent white rather than orange when the furnace lights.
My meter only has 4 "lights" on it. A light for 110, 220, 277, 460. So I assume that it possibly is getting the proper voltage, but the limitation of my meter wont allow to get a higher reading. It just has the lights and it lights up the 110 light only. I will test this again with a borrowed meter when can let know results.

As far as the igniter, It gets a VERY bright color orange. I have watched this happen hundreds of times last few weeks and would never describe it as looking incandescent white when it lights. It always looks the same to me when it is on trying to ignite. very bright hot hot coal looking orange at its brightest point.

I notice that it seems to light better when it has been running frequently. Not sure if thats a coincidence or even relavent here. I would say it is lighting on first try approx 60% of the time, on 2nd or 3rd try approx 30% of the time, and not lighting at all and going to system lockout approx 10% of the time.
 
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Old 11-17-11, 05:14 PM
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Just witnessed furnace try to start twice with no ignition. The circuit board was blinking fast indicating a normal call for heat. It tried to ignite twice with no ignition. Then the furnace inducer motor stopped and the board started blinking slow flash indicating "normal no call for heat". Seems not right to me. The thermostat was not tampered with in last hour whatsoever when it did this. Just trying to post anything this system is doing to help better diagnose issues.
 
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Old 11-17-11, 05:33 PM
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Originally Posted by ttype86 View Post
Just witnessed furnace try to start twice with no ignition. The circuit board was blinking fast indicating a normal call for heat. It tried to ignite twice with no ignition.

The inducer motor was on and stayed on during these attempts to light? Did the main burner gas switch on during these ignition trials?
 
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Old 11-17-11, 09:05 PM
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Originally Posted by SeattlePioneer View Post
The inducer motor was on and stayed on during these attempts to light? Did the main burner gas switch on during these ignition trials?
The inducer motor came on as usual when called for heat. After failed first attempt, the inducer stopped after approx 45 sec or so and started right back up and started process of ignition again. failed 2nd time as well. The gas DID switch on during both failed attempts. I was standing there listening to verify this for sure. I am 100% sure the gas kicked on and failed to ignite both times. Shortly after 2nd failed attempt, circuit board started blinking the normal code for "normal no call for heat". This "normal no call for heat" code displayed on the circuit board until the next "normal call for heat" (5 min later) code displayed in which the furnace then started this process again as usual and then DID ignite on the first try and ran as usual. Since then (earlier this evening) it has ignited on 1st attemp everytime.

I borrowed a voltmeter and have checked the igniter voltage several times and it has read at approx 121.5 VAC every time during call for heat when the igniter is on and/or glowing. I have tested the voltage during the entire stage of the igniter glowing. Every time I have checked it, it has ignited 1st try. I havnt yet been able to test the voltage when system DOES NOT ignite.

I assume at this point the best thing for me is to get a good reading on the meter at the igniter when the furnace DOES NOT ignite?
 
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Old 11-17-11, 10:35 PM
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Yes, checking the voltage when the burners fail to ignite would be a useful check. It's possible if unlikely that the hot surface ignitor isn't getting sufficient voltage to get hot enough to light the gas.

But according to your description, it's not attempting to light when there is no ignition. Instead the ignition control goes from signaling a normal call for heat to no call for heat, and thus no ignition.

In your first post you reported that the gas switched on and failed to ignite. These are two separate issues.

Unless the voltage is low when the burners fail to ignite, you need to replace the ignitor which apparently isn't getting hot enough to light the gas reliably.
 
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Old 11-18-11, 05:10 AM
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[QUOTE=SeattlePioneer

But according to your description, it's not attempting to light when there is no ignition. Instead the ignition control goes from signaling a normal call for heat to no call for heat, and thus no ignition.

In your first post you reported that the gas switched on and failed to ignite. These are two separate issues. [/QUOTE]

Im not sure where you are getting that it wasnt attempting to ignite. I may have not explained it right. It did attempt to ignite. But after the 2nd failed attempt, it stopped trying and I noticed that the board then changed its blinking code to a normal no call for heat without ever firing up. Maybe I should throw that odd occurance out. Perhaps a warm draft hit the thermostat and it went up a degree. Anyways I will continue to check the voltage and try and catch it on a failed attempt. My guess is its gona be the same but still like to know. I think I am going to replace the igniter.
 
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Old 11-18-11, 07:00 AM
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There is a good probability that replacing the ignitor will solve the problem, and perhaps further testing on the voltage issue isn't worthwhile.
 
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Old 11-18-11, 09:23 AM
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I am going to order the igniter today and order a new flame sensor as well. I will first just replace the igniter and not replace the flame sensor and give it a few days to see what happens and let know results. Your help is very much appreciated! Thank you for taking your time to help out!!! Wish my system luck.
 
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Old 11-18-11, 09:40 AM
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Frankly, it's very unlikely that the flame sensor is a problem. It's just a hunk of metal connected to the circuit board, and very little can go wrong with it other than it needing cleaning.

But suit yourself.
 
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Old 12-08-11, 02:34 AM
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I wanted to post back my results after a week or so following the igniter being replaced. Well it has actually been a couple weeks now. My furnace has ignited perfectly on the first attempt ever since replacing the igniter!!! I noticed right away that the new igniter seems to glow a little brighter than the old one. Also notice that now the burners will ignite instantly once gas valve opens. With the old igniter, I would hear the gas hissing for a couple seconds and THEN the furnace would ignite on the times that it did ignite. Now I dont even hear the gas hissing at all because it ignites instantaneously. Funny that replacing the igniter was my first instinct. But I dont like throwing parts at something without being sure. My system is up and running great now!!! Thank you for the help and saving me another service call!!!

P.S. Only reason I bought the flame sensor is because mine has a noticable gouge in it and looks like it may be getting worse. Shipping was the same with it in the order and it was only $12.
 
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Old 12-08-11, 06:04 AM
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Congratulations on your successful repair!
 
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Old 12-12-12, 09:03 AM
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Good morning! I am having the same exact issues as the previous poster....except the first thing I replaced was my ignitor. After I replaced it, I was not as lucky and my furnace didn't fire up like his. Mine will still go through the cycle a couple of times and then quit trying to start. After a couple of failed attempts the blower motor starts running.

You guys speak of blinking lights and control boards...where do I find such an animal? Is it behind another panel that doesn't have the regulator/burners/igniter ect in there?

The other thing I have not tried yet is cleaning the flame sensor. I will attempt that tonight. Anything else I should try?
 
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Old 12-12-12, 09:46 AM
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If your furnace is reaching the point of having the burners light, only to go off after a few seconds, then the flame sensor may need cleaning,

The removable panel which hides the main blower is where you should find the control board and list of codes. Some furnaces have a peek lens on that panel so you can see the codes without removing the cover.

This panel usually has a safety lockout which will cut the power when it is open.
 
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Old 12-12-12, 10:48 AM
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Well the burners never get lit. I hear the gas come out of the pipe/nozzles but to me it seems like the igniter is going out by the time the gas hits the electrode. It seems like the igniter needs to stay on 10 seconds instead of 6 or 7. Any thoughts on that?

Hmmm, I will have to do some looking but I didn't see any sight glasses anywhere on the thing.
 
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