A Falls Church welder, Matthew W. Homolik, patented his two-year-old idea for circulating-air stoves recently, and he's moved on to manufacturing and selling the custom-built stoves.

Homolik, 58, owner of Central Welding & Stove Manufacturing Service, received U.S. Patent No. 4,361,131 for a "circulating-air heating stove with exit air heat extractor" (11 claims). He's sold 15 of the stoves, which go for $700 to $1,500. They're made of sheet metal to fit any size fireplace.

This invention consists of a rectangular box resting on feet, permitting air to flow under it into a pair of electric blowers in the back. Air from the blowers flows over the top of the heating unit--fueled with wood, gas, coal, oil, etc. The heated air then flows into the room or is channeled through air ducts to other rooms. This stove can be made small enough for one room or large enough to heat an office building or hotel.

Homolik says his stove does not allow hot air to be lost up the flue. It has a closed front with a door.

Patent fees were raised on Oct. 1, 1982, to $150 for individuals, businesses under 500 employes and nonprofits, and $300 for all others. VIRGINIA

Wallace E. Atkins of Petersburg, changeable combination lock for desk drawers and the like. No. 4,366,687, 8 claims.

Norman B. Rainer and Dean M. Siwiec of Richmond, process for expanding tobacco. No. 4,366,823, 23 claims.

Norman B. Rainer of Richmond and John R. Hearns of Chesterfield, process for expanding tobacco. No. 4,366,824, 21 claims.

Francis V. Utsch of Midlothian, et al., expansion of tobacco. No. 4,366,825, 2 claims.

Donald C. Kirk Jr. of Midlothian, child-resistant closure device. No. 4,366,921, 12 claims. MARYLAND

Thomas E. Judkins of Baltimore and Thomas J. Stanton of Ellicott City, fastener strip for building wall construction. No. 4,366,692, 4 claims.

James J. Kakibbin of Baltimore, packaged sprinkler system using a dead water tank. No. 4,366,865, 6 claims.

John Ravinsky of Rockville, thermal tool including twisted tip for the tool and method of making tip. No. 4,367,396, 25 claims.

Daniel H. Schaubert of Silver Spring, et al., frequency-agile, polarization-diverse microstrip antennas and frequency scanned arrays. No. 4,367,474, 10 claims.

Whitworth W. Cotten Jr. of Germantown, et al., subscriber station for providing multiple services to a subscriber. No. 4,367,548, 12 claims.