Performed a heating system check-up in Ivyland, PA 18974 for both upstairs and downstairs units. Replaced filters for the upstairs system (16x25x1) and downstairs system (20x25x1) and noted that the downstairs filter cabinet supports a higher-rated 20x25x4 filter. Identified an incorrect thermostat on the first-floor system that was causing both the heat pump and gas furnace to run simultaneously, risking compressor damage. Recommended replacing it with a dual fuel thermostat for safe, efficient operation.
