问了师傅,他说我的14 seer, 没必要到2 stage, 倒是建议升级到TUD1. 感觉师傅靠谱。老美估价比他贵2000 左右。师傅的回答 【 About $400 ,more . If you want tud1b060a $100 more. Tud1a040g9h21a(xt80) or tud1a040a9241a(xr80) $100 more. I might give you a(14") instead b(17") to match your old furnace size . Only they don't have a will give you b . Same price . No recommend 14seer use 2 stage. But up to you 】 TUD2