4 system furnace maintenance complete. Changed downstairs and basement filters. Left replacement filters for 3rd and 4th floor systems. Dusted out furnace cabinets. Tested main level furnace. There is mold in the supply plenum, recommend indoor air quality product to eliminate mold, bacteria, germs, viruses and volatile organic compounds for improved air quality. Found worn igniter, recommend repair. Combustion readings are good with normal oxygen and carbon monoxide levels. System only has one form of water safety, recommend adding on second form of water safety to protect furnace from potential water damage and to act as a backup to existing water safety in the pan beneath the furnace. Tested basement heat pump system. It has a weak capacitor in the heatpump on the fan side of the capacitor (30/5). Recommend repair. System has only one form of water safety, recommend adding second form onto system. Aside from the capacitor, the system has no other mechanical concerns.