Two weeks ago a technician came to our house (in Broken Arrow, Oklahoma) for our semi-annual "Energy Savings Agreement" service call. I have been very satisfied using this same company for over 20 years. This call was to service the furnaces. Our gas furnaces are Goodman, GMP100-4-RevB and GMP050-3-RevB. Included in the work performed was the following for both units:

1) Cleaned burners and exchanger
2) Cleaned flame sensor
3) Adjusted gas pressure to 3.5

I hadn't thought anything of the work performed until yesterday when I read some disturbing information on this forum regarding adjusting gas pressure. Is a gas pressure adjustment to 3.5 safe or should I be concerned?