Furnace third burner won’t come on

furnace

I have a Trane furnace and the third out of three burners doesn't want to come on. The surface ignitor will light, the gas to the first two burners kicks on, but the third burner that that shoots flames into the flame sensor doesn't come on and then the furnace will shut off in a couple seconds and then will try to repeat this for a few times. Sometimes it will eventually light, but sometimes it won't.

Do I just need to take the burners apart and give it a good cleaning? I'm a self admitted cheapskate and like to do the work myself to save money but when it comes to anything that has to do with gas, sometimes I'll fork over the money to hire a technician. Is this something that's easy enough to do myself or just go ahead and get a hvac guy out? I've done many home repairs successfully with the help of youtube but this particular one I'm having a hard time finding a detailed video that goes through steps.

Best Answer

I agree with the response above it is imperative that your gas pressure be right. Manifold pressure is 3.5" in our area. Although if you pressure was significantly down I doubt if any of the burners would light. Let me tell you what I ran into one time. I basically had the same thing, three burners would light just fine but nothing on the fourth. I checked my pressure, all good. It was also the first start-up in the fall. I pulled the manifold out and started looking at orifices. I was checking the bore on the orifices. I looked into the #4 orifice and I saw what looked like a white film. Now I'm totally scratching my head. I unscrew the #4 orifice. Out comes a family of I mean tiny spiders. I had never seen spiders so small, like half the size of a period on the end of a sentence. They were so small that they could easily crawl through the orifice. The white film was actually spider web. They had webbed across the orifice opening from the inside. The 3.5" of gas pressure was not enough to break through the web. It totally blocked the gas. I asked the customer for a Que-tip, swabbed out the opening, put it all back together and away she went. Good Luck!