Trane XR90 Igniting/Pressure switch issue?
As I posted in my welcome post, I have been having issues with my furnace on and off for months now. I have the EXACT issue another user described in another thread (that I will post below), and he has the same furnace as me.
I have a furnace that will sometimes produce a pressure switch error, sometimes I don't get that error, sometimes the furnace will get the call for heat, it will go through the process, the ignitor will glow, and then the furnace will try to ignite but won't. It will try, it makes 3 attempts or so, and then it will go into lockout for the 2-3 hours blowing cold air. I can get the furnace to fire 100% of the time if I remove the tube coming from my differential pressure switch (the right side) which is the tubing that reads the vacuum from the intake I believe. The left tube goes to the heat exchanger?
Like the original poster mentions as well, if its cold outside I hardly have ANY issues. If its cold, but more in the 32-50 range and its wet and rainy outside, this is when I have all the issues. I have had 4 techs out now trying to solve this and every tech tells me something different. One is afraid its a heat exchanger issue (but never ran any combustion tests). One thinks its the burners and the ignitor. Now the guy that I just had out 25 minutes ago thinks it could just be the pressure switch. He read the vacuum and got 1.35 on the one side, and .16 on the other. I guess my pressure switch needs to be above 1.15 to fire, so it should fire with that vacuum? I am still concerned something else is causing the issue and that is why it will work sometimes and not work other times.
I have already paid to have my exhaust and intake venting moved because I thought that could have been the issue, but that never solved it. I have no idea what to do.
Anyways, here is the link to the original post. If you want to read it, the member (dkenne) posts sum up the issue I am having. It is LITERALLY identical.