Repeated problems with the flow switch system have likely stemmed from changing water pressure at the school, which should be corrected by adjusting pressure sensitivity, he said.
Deputy Chief State Fire Marshal Charles M. Cronauer said he will close the school if the problem isn't corrected by the deadline.
Cronauer said his inspector wanted to order the school closed until the problem is fixed but he interceded to give the school system ample warning.
School wasn't closed on Wednesday because the problem doesn't endanger students, McGee said.
Many of the system's older schools don't even have sprinkler systems, he said.
McGee said the sprinklers themselves are working fine. The flow switch system is mainly for property protection, to signal authorities when a fire starts while the building is unoccupied and the sprinklers are activated, McGee said.
He said the school's pull alarm system is the first line of defense to get everyone out of the building safely.
"There's 800 kids in that school. If something is on fire, somebody is going to see smoke and pull an alarm," McGee said.
Smoke alarms in the air ducts are the second, he said.
The sprinklers flooding the building would be the third, McGee said.
The way Cronauer sees it, the other warning mechanisms don't lessen the importance of the flow switch system, which can mean valuable time in evacuating the building.
"When you go to get out of a house, three minutes can make the difference between life and death," he said.
Boonsboro Middle would be closed if school officials didn't feel there was still an adequate fire alert system and students were safe, said Acting Schools Superintendent Linda F. Barkdoll.
School Principal Janice Gearhart said she wasn't worried about having students in the school because she trusted central office staff wouldn't keep the school open if it wasn't safe.