Furnace Maintenance: Adjusted gas pressure to meet manufacturing pressure of 1.7wc in low stage. Added water to p trap to stop the siphoning sounds "clug-clug-clug". Flushed the condensate drain lines to maintain clear, efficient flow. Checked pressure switch tubing to ensure reliable performance. Cleaned and polished the flame sensor for optimal ignition. Ran full diagnostics to confirm the system is running smoothly and efficiently.