The shares closed at $61.06 in a broad market rally, with the S&P 500 up 1.46% and the Dow Jones Industrial Average up 1.24%.
It was A.O. Smith's second straight daily gain, but Carrier Global rose 5.80%, while Trane Technologies and Lennox International also posted advances.
The stock remains 25.41% below its 52-week high of $81.87 reached on 12 February, while trading volume of 1.9 million topped its 50-day average of 1.5 million.
Can A.O. Smith's heat pump strategy overcome its major sales slump in China and justify a higher stock price?
Analysts call A.O. Smith undervalued, yet Goldman Sachs says sell. What key risk are most investors overlooking?
How will new energy rules forcing a shift to costly heat pumps impact A.O. Smith's core replacement market?