A 32-year-old Edgewater, Md. man, who was critically burned in a 1980 flash fire in his basement, has won an out-of-court settlement for payments totaling at least $25 million spread over the rest of his lifetime, his attorney said yesterday.

The plaintiff, Patrick A. Butcher, a YMCA camp director, had filed a personal injury suit against Robertshaw Controls Co., of Richmond, the maker of a device controlling the flow of liquid petroleum gas to his water heater.

The settlement was hailed by Butcher's attorney, J. James McKenna of Rockville, as "the biggest in this area in memory. It's a very complicated package. It includes a sizable amount up front, plus an annuity."

While declining to outline terms of the agreement, E. Charles Dann Jr., the attorney representing Robertshaw, disputed the $25 million figure yesterday, saying "it won't be that much in terms of the value of the dollar today."

"All I know," replied McKenna, whose contingency fee is approximately one-third of the settlement, "is that five years from now my man will be getting $225,000 a year, compounded at 6 percent interest annually. That's spread over his entire life and makes up only one portion of the package."

Butcher expressed satisfaction with the settlement yesterday, but added that "it's not like winning the lottery. I intend to provide for my family and kids. This will give me a head start."

The settlement represents only the latest setback for Robertshaw, a worldwide manufacturer of controls for gas water heaters that has been inundated in recent years by civil litigation.

The Richmond company was sued last June for $500,000 in civil penalties by the Consumer Product Safety Commission for allegedly failing eight years ago to report 47 deaths and 93 injuries from explosions and fires over a 20-year period allegedly caused by the same type of gas water heater control that prompted Butcher's suit.

On Aug. 20, 1980, Butcher went to the basement of his house, which is on the grounds of the YMCA's Camp Letts, near Annapolis, to see whether the pilot light on his gas water heater was operating. According to McKenna, Butcher smelled gas and turned to leave when he was enveloped by flames.

McKenna charged that a control device, which is supposed to stop the flow of liquid petroleum to the heater when the pilot goes out, failed to operate, and that the liquid petroleum continued to feed the heater. "It's a very volatile fuel," he said. "One spark and the whole place goes up."

Butcher was burned over 85 percent of his body, hospitalized for two months and underwent a series of skin of graft operations. He and his wife filed suit two years ago, and Friday, after a jury had been selected to hear the case in U.S. District Court in Baltimore, McKenna and Dann, after weeks of negotiation, reached an agreement.

McKenna said the settlement calls for annual payments to Butcher, or his wife if she survives him, and to their two young children after that.

Butcher said yesterday he remains disfigured by the fire, and has lost the use of his left hand and most of his mobility. "I was an avid sportsman before," he said. "Now I'm restricted to a little physical therapy and some racket sports.

"It's over as far as the suit is concerned, but not for me, personally," said Butcher. "I have to live with this. I still have very strong feelings about Robertshaw and what they've done to me."

Several telephone calls by a reporter to Robertshaw's Richmond headquarters were not returned yesterday. The company specializes in worldwide manufacture of automatic energy controls and control systems for residential and commercial buildings. It reported total sales of $351 million in 1981.