Customer completed CCM form for three systems today. Performed heating maintenance on three systems. Upstairs and main level are located in the attic and are gas furnaces. The basement system is located in the basement and is a heat pump. Upstairs and main level systems can utilize 16 x 25 x 1 filters or 20 x 25 x 1 filters. Both have older April, air filter housings. Basement system has a 15 x 20 x 1 washable filter. Filter must be washed because other filter sizes will fall down and not fit properly. Cleared and treated condensate drain lines. Inspected electrical connections and components. Technician did show homeowner basement thermostat in effort to avoid emergency heat position. All three systems are operating normally at this time.