Environmentally Sound, Money-Saving Comfort At Bryant, we believe that home comfort equipment should offer lasting comfort and value. That's why we designed the model FX4, FC4 & FB4 Fan Coil with Puron. In addition to the comfort and reliability you'd expect from a matching Bryant fan coil. Models FX4, FC4 & FB4 use Puron, the new, environmentally sound refrigerant. 1. Enhanced Efficiency And Durability Is provided by the Thermal Expansion Valve (TXV), which precisely measures the liquid refrigerant. (FC4 only) 2. Quiet Indoor Comfort Is one of the benefits of extra-thick cabinet insulation. 3. Long-Term Durability Of the fan coil is protected by the pre-painted, corrosion resistant cabinet. 4. Easy Maintenance Is ensured by the easy, no-tools-required access for routine filter cleaning or replacement. 5. Cleaner Indoor Air Is provided by the enhanced design of the drain pan. Made of non-corrosive material, this drain pan improves indoor air quality through better drainage of condensate. 6. Reliable Comfort Is delivered by the electric resistance heaters which provide back-up heat when outdoor temperatures are extreme.