The MRCOOL® Signature Series 42k Multi-Position Air Handler is built to provide consistent, energy-efficient comfort in any climate. Designed for flexibility and performance, this unit works with R-454B refrigerant, a low-GWP alternative that helps reduce environmental impact without sacrificing power or reliability. Its multi-position design allows for installation in upflow, downflow, or horizontal configurations, making it ideal for a variety of home layouts, from new construction to tight retrofits. With its slim, space-saving profile, it fits easily into closets, attics, or crawl spaces while still delivering full-capacity heating and cooling when paired with a compatible condenser or heat pump. Engineered for durability, the air handler includes a galvanized steel cabinet, a high-efficiency ECM blower motor, and copper “A” coils with enhanced aluminum fins for superior heat transfer and humidity control. Thermal insulation inside the cabinet reduces energy loss and prevents condensation, contributing to quiet operation and lower energy bills. Installation is fast and simple, helping to minimize labor time and disruption. An air filter rack allows for easy maintenance, while an optional electric heat kit is available for added heating performance in colder regions. Smart home compatibility comes standard, with support for most third-party thermostats so you can manage comfort on your terms; no proprietary systems required. Protected by a 10-year limited parts warranty, the MRCOOL® Signature Series 42k Multi-Position Air Handler offers long-lasting performance, space-saving design, and year-round efficiency for today’s comfort-conscious homeowner.