pookie16

Wind gusts on the roof causing back pressure in the flue. This would not depend on the physical location of the actual furnace. That is what I meant. It makes sense to me, and I say it is a bad design in that if the wind caused back pressure, and then the situation is resolved, it should not require manually reseting the furnace. If I was king, I would change it so that if the furnace is running for several hours in 3 blinks mode, it should reset itself.

Furnaceguy59

It shouldn't require resetting the furnace and Trane knows this. And, I think the dealers know it. And, there's nothing they can do about it unless you replace logic boards with updated firmware. I have no way of knowing this but I'm sure either the firmware has been updated and/or the pressure switch is different on newer models. When I get some time, I'm going to prove my, and my tech's theory. I'm going to take my leaf blower outside and blow varying degrees of wind into the exhaust and intake pvc runs to see if I can duplicate a strong gust of wind resulting in a change in pressure on the switch, shutting the furnace down and getting the 3 blinking lights.

paul52446m

Any 90+ furnace can be effected by outside air blowing into the stack That is why i don't like venting them through the side wall. I would rather go through the roof. If you have wind problems and you are through the side wall. instead of going straight out, you might want to but a tee so the wind can't blow in. I live in a cold area and when we first started with the 90+ furnaces we were told by the factory how to run the stacks and we had to start changing the way we run stacks right away. I usually run the intake pipe it a vented attic with a 1 foot long screen on it. This way the wind will not bother it as much. If i have to side wall vent, i try to go out where i will not get the prevailing winds. Some times just reducing the stack on the out side will blow the fumes out harder so it will maintain better pressure in the stack and the wind will not bother it as much. Paul

lostpilot28

Just wanted to post a quick update...I finally got my XE90 fixed. The heat exchanger was replaced, because the old one had a huge crack in the plastic interface part where the exhaust gas exits. Surprised I'm still alive to tell you about this!

Anyway, that huge crack was allowing the pressure to normalize between the front and the back burners...when it should've been over 1.5" H2O, it was only around .9".

MarkBean

THANK YOU! You helped me restore heat to my house just as hurricane Sandy is hurtling towards us. I scanned the internet looking for ways to solve this problem. After over an hour of educating myself on how to troubleshoot/repair I went up into my attic with all a number of tools, WD40 and my voltmeter. The one "tool" that solved the problem was a paper clip. I didn't see any blockages but after removing the tube and then sticking a paper clip in the tiny hole of the blue valve of the pressure switch, I was back in business.

Now I'm just a bit concerned and want to make sure that I didn't possibly hurt the pressure switch and put it into a permanent on mode by pushing the paper clip in until it stopped. I'd sleep a bit easier if someone could confirm that one can't hurt the switch in this manner.

On another note, I did see some bug carcases behind the glass porthole before the burners. Should I be concerned about them?

Bigdog1

I too checked the bottom trap for clogs and dirt. Nothing. Exhaust Fan motor works. No problem with my flue pipes.

Did the old paper clip trick and the furnace is running.

I had to do it a few times because I don't think I was deep enough the first couple times. But I also wanted to be gentle...

It's very windy and I have had this problem before during WIND events...

Piss poor design if you ask me...Nothing keeps the repairman coming back like a Trane.

On a side note my heat exchanger has already been replaced because of a huge crack...and the BLOWER motor too...

The last time I had a 3 flash problem the water trap at the bottom was clogged...That was my first stop this time...

Thanks guys....

nealtw

MarkBean and Bigdog1; Sorry I can't offer any insight but welcome and thanx for sharing.

Bigdog1

The problem came back. I did the paper clip again and the furnace fired up but it has since shut down again.

pookie16

I see I never posted an update. I was working out of town and my wife was shutting the furnace off and restarting it to keep the house warm. I got a repair man in. His theory was that if the cycle time was too short, the vacuum in the flue was not dropping enough to let the switch open. He put a smaller diameter and longer hose to the switch and increased the temperature differential to restart the furnace. It seemed to work, so he left with some of my cash, but with the guarantee to come back if the problem was not fixed. A day later, the problem came back. I was out of town and my wife went back to restarting the furnace manually. Before I got back to town, the problem just went away. It is now a year later or so and the furnace seems to be working.
I will reiterate the person's comment that said this is a poor design. I also thought Trane was a good brand when I bought this new furnace. The old one (FlameMaster) supposedly had a leaky heat exchanger, but it worked for 17 years that way with one belt replacement. This new one has broken down on two different problems in 3 years.

Bigdog1

Well this is interesting.

It stopped working again and went back to three flashes. I did the paperclip thing again a few more times. It would light and shut down. I took the hose off to the presure switch and the furnace fired up and ran like normal. With the hose off now it has been running normal for 24 hours...WITHOUT THE HOSE...


Furnace repair guy is coming this morning...I can't wait to hear what he says about how it's running normally... and flashing no code.