Donald J. Heim has been elected president of Washington Gas Light Co., as part of a series of top-level management changes at the utility.

A Washington Gas employee since 1950, Heim has been vice president for corporate planning and services during the past five years.

He succeeds Paul E. Reichardt as president but Reichardt remains as chairman and chief executive officer. Helm also was elected to the company's board of directors to succeed Thomas J. Owen, a director since 1969 who said increasing demands on his time as president of Perpetual Federal Savings and Loan necessitated his resignation.

A company announcement said Reichardt, president for eight years, had recommended a series of management changes "to take full advantage of opportunities for further corporate growth."

In addition to Heim, those persons promoted were:

R. C. Vierbuchen as executive vice president, in charge of non-operating subsidiaries. He has been with the firm 27 years, most recently as vice president for consumer services and public affairs.

J. L. Blincoe as vice president for consumer services and public affairs, succeeding Vierbuchen, Blincoe joined the company in 1936 and has directed customer relations.

J. K. Hughitt to succeed Heim with expanded responsibilities for corporate planning, services and rates. He has been with Washington Gas for 28 years.