Baltimore Gas and Electric Co. reported its January common stock earnings fell to $8.55 million (27 cents per share) from $9.29 million (30 cents) despite a 6.8 percent increase in electricity sales and a 2.1 percent gain in gas consumption.

The big Maryland power company said a new two-tier electric rate structure implemented last month results in lowerrevenues in the winter and higher income in the summer, but said the changes balance out over the year.

For the 12 months ended Jan. 31, Baltimore Gas reported common stock earnings of $103.6 million ($3.36) compared with $84.2 million ($2.82) a year earlier.

Total operating revenues increased to $96.3 million from $85.5 million for January and to $985.3 million from $793.8 million for the 12 months.

Heck's Inc., the Charleston, W. Va., discount department store chain, reported a 40 percent increase in profits on a 30 percent sales gain for 1978.

Heck's earnings for the year were $10.7 million ($1.71 per share), up from $7.7 million ($1.14); sales increased to $285.5 million from $220.2 million.

Chairman Fred Haddad said the gains are "the sharpest year-to-year increases ever recorded by the company" and attributed the increases to a strong holiday selling season, the opening of nine new stores and the acquisition of Felsway Corp. last October. Felsway operates 140 retail shoe stores, and Heck's has 71 discount stores, 63 women's shops and several diversified subsidiaries in wholesaling and leasing.

For the final quarter of 1978, Heck's reported net income of $5.4 million (84 cents), up 58 percent over the $3.5 million (56 cents) of a year earlier. Sales for the period jumped to $114 million from $75 million.

Doughtie's Foods Inc. of Portsmouth, Va., reported a 15 percent increase in sales for 1978, but said its earnings increased only a penny a share to $600,000 (87 cents) from $591,000 (86 cents).

Doughtie's, which acquired Parks Seafood Inc. last July, reported sales for the year of $32 million, up from $27.9 million.

For the fourth quarter the firm earned $128,000 (18 cents) on sales of $8.6 million, up from $127,900 (18 cents) on sales of $7.6 million.

PHH Group Inc., the Hunt Valley, Md., firm that specializes in leasing and other business services, reported net income for the nine months ended Jan. 31 increased 23 percent to $8.74 million ($1.43 per share) from $7.13 million ($1.18).

The company, which recently was listed on the New York Stock Exchange, reported third quarter earnings of $3.12 million (51 cents), up from $2.61 million (43 cents), and said revenues increased 35 percent to $49.9 million from $36.8 million.