Jan 29 (Reuters) - A.O. Smith AOS.N posted a rise in fourth-quarter profit on Thursday, aided by strong demand for its residential and commercial boilers and water treatment products in North America.

"Our China margins expanded despite ongoing pressure on volumes due to challenging market conditions,” CEO Steve Shafer said.

In July, the company had said it will explore strategic partnerships and other options for its China business.

A.O. Smith's adjusted net income for the fourth quarter was $125.4 million, or 90 cents per share, compared with $109.7 million, or 75 cents per share, a year earlier.

The company's sales in North America rose 3.5% from a year earlier to $713.7 million, as favorable pricing and improved water treatment profitability offset higher input costs.

The Milwaukee, Wisconsin-based company's total revenue for the quarter ended December 31 was $912.5 million, compared with $912.4 million a year earlier.

A.O. Smith expects full-year profit per share to be in the range of $3.85 to $4.15.

(Reporting by Apratim Sarkar and Megavarshini G. Somasundaram; Editing by Sahal Muhammed)

((Apratim.Sarkar@thomsonreuters.com;))