Jake Kring. 10-30-24. I arrived for a fall tune up blue club membership. I spoke with the homeowner and found that they have been using the system and hav had no issues with the system. I first inspected the filters and found the, to have been replaced. I left the homeowner with a replacement set that comes with his blue club membership. I then inspected the furnace and cleaned the flame sensor and checked the systems cleanliness. I then checked the systems operation and found the gas pressure to be running at 1.9 IWC and the o2 reading in the stack was 13% o2 and above. The homeowner and I raised the gas pressure from 1.9 to 3.8 IWC and watched the changes in the combustion readings. We let the system settle for 5 minutes and found the o2 readings to drop to 8.6% o2 and the range for the o2 readings are be 6% and 9% of o2. We also found the temperature rise from supply and return to be 16-17 deg while we ran the system. Overall this system is running within manufacturer specifications