Serviceman came out, but could not reproduce the problem,. They suggested to change ignition switches. I paid service visit fee, but held off changing the switches. The problem happened the next day again. I was going to call them out again, until I called a different company. They worked with me by phone, and suggested I wipe the burner sensor - easy fix. It corrected the problem. My question is why wouldn't they have have at least tried this simple maintenance task before recommending I change the switches for $500 - $600. By the way, I used them to install the system 5-6 years ago. Maybe it was an oversight, but the other company was more supportive and did not even charge me.