Arrived on site to perform furnace maintenance on Lennox heater. Cycled system for heat. Verified proper heating sequence of operations. Temperature rise across heat exchanger is within range. Ran system through 20 point inspection checklist. Filter is dirty, homeowner will be ordering and replacing. Air scrubber bulb is burnt out. Homeowner has been aware of this and doesn’t wanna replace it. Also went over the buyback program for the new Air purifiers. Recommend surge Protection . System is operational upon departure.