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Trane XR80 Furnace - gas valve not opening - test pictures and video included
BlakeHH
Member Posts: 3
Hello!
My heating furnace came on just fine when I initially called for heat at the thermostat. It ran for probably a full day or two. Woke up one the next morning and there was no heat, just the fan blowing.
After watching a lot of videos and reading a lot of posts, I've done what I can do diagnose the issue, but after still not being able to solve the problem, I'm now at my wits end!
It's a Trane XR80 White Rodgers 36G22-254 gas valve.
The startup process makes it all the way through to heating the HSI and energizing the gas valve. But the gas valve never seems to open.
It tries a couple more times until it eventually times out with an diagnostic error code of
TWO flashes, which is listed as "External lockout (retries or cycles exceeded)".
Here's a video of the full cycle:
https://1drv.ms/v/s!AjMAHbhAdjR5xcskE65276db2mgJcg?e=3ksMOa
I've tested the wiring going up to the gas valve and can confirm it is receiving ~28 volts for a few moments after the HSI glows:
https://1drv.ms/v/s!AjMAHbhAdjR5xctu8QU5yXvRu7CEoA?e=v8b3Ai
A continuity test on the gas valve terminals reads just below 1.0
Gas pressure test on the in port reads just below 10" WC. I don't have the attachment "straws", so I simply firmly held the tubing to the inlet.
This seems a tad high compared to the other videos and such I've read, but is still within the max allowance of 13.8" WC.
Gas pressure test on the out port reads zero, zilch, nadda. In this instance I was able to force the tubing onto the inlet.
There is a FAINT sounding click just after the HSI ignites but with all the noise going on, it's hard to tell if it's coming from the gas valve or somewhere else.
I've heard some say it's possible to put your hand up to the gas valve housing and "feel" the valve click over, but I'm not able to sense anything like that from this one.
The flame rollout sensors/switches don't appear to be tripped, though I must admit I'm not entirely sure what I'm looking for there...
Since volts were getting to the valve, from what I've read/seen, this seems to indicate a faulty gas valve. So I just put on a brand new one (this is the valve in the test results above). While I had the manifold off, I did check the little holes, clean them with a paperclip.
I also removed and cleaned the temperature sensor, though my understanding is that comes into play AFTER the burners have fully ignited.
As for the gas valve, I've heard people say that solenoids rarely go bad. To think I had not one, but TWO be bad, one of them straight off the shelf? That seems like a stretch...
Any ideas of what else I could check? Thank you in advance!
My heating furnace came on just fine when I initially called for heat at the thermostat. It ran for probably a full day or two. Woke up one the next morning and there was no heat, just the fan blowing.
After watching a lot of videos and reading a lot of posts, I've done what I can do diagnose the issue, but after still not being able to solve the problem, I'm now at my wits end!
It's a Trane XR80 White Rodgers 36G22-254 gas valve.
The startup process makes it all the way through to heating the HSI and energizing the gas valve. But the gas valve never seems to open.
It tries a couple more times until it eventually times out with an diagnostic error code of
TWO flashes, which is listed as "External lockout (retries or cycles exceeded)".
Here's a video of the full cycle:
https://1drv.ms/v/s!AjMAHbhAdjR5xcskE65276db2mgJcg?e=3ksMOa
I've tested the wiring going up to the gas valve and can confirm it is receiving ~28 volts for a few moments after the HSI glows:
https://1drv.ms/v/s!AjMAHbhAdjR5xctu8QU5yXvRu7CEoA?e=v8b3Ai
A continuity test on the gas valve terminals reads just below 1.0
Gas pressure test on the in port reads just below 10" WC. I don't have the attachment "straws", so I simply firmly held the tubing to the inlet.
This seems a tad high compared to the other videos and such I've read, but is still within the max allowance of 13.8" WC.
Gas pressure test on the out port reads zero, zilch, nadda. In this instance I was able to force the tubing onto the inlet.
There is a FAINT sounding click just after the HSI ignites but with all the noise going on, it's hard to tell if it's coming from the gas valve or somewhere else.
I've heard some say it's possible to put your hand up to the gas valve housing and "feel" the valve click over, but I'm not able to sense anything like that from this one.
The flame rollout sensors/switches don't appear to be tripped, though I must admit I'm not entirely sure what I'm looking for there...
Since volts were getting to the valve, from what I've read/seen, this seems to indicate a faulty gas valve. So I just put on a brand new one (this is the valve in the test results above). While I had the manifold off, I did check the little holes, clean them with a paperclip.
I also removed and cleaned the temperature sensor, though my understanding is that comes into play AFTER the burners have fully ignited.
As for the gas valve, I've heard people say that solenoids rarely go bad. To think I had not one, but TWO be bad, one of them straight off the shelf? That seems like a stretch...
Any ideas of what else I could check? Thank you in advance!
0
Comments
-
If your getting power to the valve it should light. Look at the board at the blinking red light and count the number of flashes when it is locked out. There is a note on the wiring diagram telling you what the flashes mean.
You might check the flue and chimney for obstructions,
could be the air proving switch for the inducer. Disconnect the tubing to it and make sure the connections are clear1 -
Okay, I'll go check! The tubing you're talking about is this, correct?EBEBRATT-Ed said:You might check the flue and chimney for obstructions, could be the air proving switch for the inducer. Disconnect the tubing to it and make sure the connections are clear
Sorry I should have made it more prominent. TWO flashes, "External lockout (retries or cycles exceeded)".EBEBRATT-Ed said:Look at the board at the blinking red light and count the number of flashes when it is locked out. There is a note on the wiring diagram telling you what the flashes mean.
0 -
If you get the HSI to glow and 24 vac to the gas valve, then, IMO it is the gas valve or gas supply pressure.
Is this LP or NG?1 -
Eureka! @EBEBRATT-Ed , your suggestion indirectly led me to to the fix!
The tube was clean, the flue was clear.
So in my frustration I started jiggling wires after the HSI lit... And yep! The gas valve opened and all burners ignited.
I cleaned off the connectors with a knife, tightened the clamps, calibrated the out pressure to 3.5" WC, and we're now in business!
Wow... What a crazy three day roller coaster!
Tomorrow I'm getting a tattoo on my forehead that reads, "When in doubt, jiggle'em about!" ha!
Thank you also @JUGHNE for offering to help!0 -
That's good glad your up and running1
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