I have had one for 6 years and have had the same problem. furnace will not lite and stay lit consistantly. have tried replacing computerboard, gas valve, and temp limit. I still have the same problem. especially during cold weather (10-30 F). Initial installer never could find the problem and it would misterously vanish when the weather became warmer.
concord technical service number is 1-800-448-5872 ext 2610 oben from 8-4:30 eastern standard time