Driven by shrinking mine supply and sustained demand, copper prices have remained elevated since late 2025, currently reaching 5 to 6 times the price of aluminum. Facing cost pressure, some leading AC brands have publicly committed to using copper for heat exchangers and connecting pipes, refusing to sacrifice product stability for short-term margins. This divergence signals to the line-set supply chain that dimensional consistency and material integrity in copper piping remain a non-negotiable baseline for downstream assemblers; low-cost aluminum substitution struggles to gain trust in high-end assembly markets.