E. Lester Barker has been elected chairman of the board and chief executive officer of Hessick Inc., a local fuel oil and heating equipment corporation. He succeeds Frederick A. Hessick, who retired last month. Hessick and his father founded the privately held company here in 1913.

Other top management changes at Hessick include the elevation of former executive vice president Ralph E. Moore to president and chief operating officer, and Ronald H. Wheeler to assistant vice president.

Barker began his career with Hessick nearly 29 years ago as a salesman. He has since served as manager of the fuel oil department and as vice president. In 1973 he was appointed president.

Moore also joined Hessick as a salesman two decades ago. Wheeler went to Hessick in 1968 as an oil burner service mechanic, and is now "a real authority" on fuel oil systems, according to Barker.

"Our last year was a good year, but that's history now," said Barker, commenting on the local fuel oil industry. "Tell me what the weather's going to do, and I'll tell you how we'll do this year."

Barker added that people are "nervous about natural gas deregulation," and predicted that gas will eventually be as expensive as fuel oil. However, it is unlikely that the Reagan administration will move on gas deregulation for at least another year.

Hessick Inc. sells "a lot of dual-fuel equipment to apartments," Barker said. Dual-fuel heating equipment can use either natural gas or fuel oil in the same burner, simply by "flipping a switch." Nonetheless, Barker said the company's oil sales are "10 times" those of equipment.