Just wondering if anybody else has the same problem with there mid efficient Rheem furnace only lighting up the burner beside the igniter instead of all three at the same time.

If your furnace only lights the first two burners, you have dirty burners not letting the flame cross over. They will need to be cleaned or you have low gas pressure. 9 out of 10 times its dirty burners.

I hate to say it but the furnace was new roughly 10 years ago and lack of management on my part I have not had the furnace or the ductwork cleaned.

Thanks for your answer T-TOP but it is only the one burner beside the igniter that lights up, would it still be dirty burners as I vacuumed the out yesterday and did not do any good, will have to get technician in.

The problem may also be rust accumulation in the main burner cross-lighter slots.

I brought my air compressor in blew all the dust out and works fine so far thanks for your help.