The simplicity of specialized HVAC packages in district heating systems and within the building envelope significantly aids maintainability. Patterson has Flo-Pak packages for steam or hydronic heating and heat transfer stations, complete chillers, water source heat pump stations, condenser water pump skids and hot water heating circulators. Flo-Pak heat transfer packages incorporate air separators, expansion tanks, suction diffusers, triple duty valves and various types of heat exchangers. Working pressures extend to 175 psig. Variable speed drives are available.