Thermostatic valves — those that open or close in response to temperature — are included in the NESOI subheading 848180, which explicitly references thermostatically controlled appliances. Parts of thermostatic valves are covered under 848190. The key is that the valve's primary control mechanism is thermal response rather than manual or pressure-driven actuation.

Accurate country-of-origin documentation is essential, since both antidumping orders and Section 301 measures are origin-specific. Detailed technical specifications — valve type, pressure rating, material, and operating mechanism — are needed to confirm the correct 10-digit HTS classification, as duty rates and applicable orders vary significantly across subheadings within 8481.