Frozen pipes and failed heating systems forced the closing yesterday of 19 public schools in the metropolitan area. Most were expected to be open today.

About 14,000 students, including those at Gaithersburg and Einstein high schools in Montgomery County, DuVal and Suitland high schools in Prince George's County, and Falls Church High School in Fairfax County, received unexpected vacations while repair crews struggled with balky boilers, cracked pipes and heating oil spills.

"This happens to us every year when there's a cold spell," said Donald Mulvanity, director of administration for facilities for the Fairfax schools. He said that the loss of only four of the county's 180 school facilities yesterday was relatively good, considering the harshness of the weather.

In most cases, students at the affected schools were sent home on the buses that brought them to school, or with parents and friends when schools were closed early.

Many school systems opened an hour or two late because of the unusual cold yesterday, but school officials throughout the area said that they expect to operate on a normal schedule today.

Schools closed because of heating problems yesterday included:

FAIRFAX COUNTY -- Great Falls and Woodlawn elementary schools, Key Intermediate School, and Falls Church High School. School officials said that work on the heating systems would continue through the night and it was not clear whether these schools would be open today.

PRINCE GEORGE'S COUNTY -- Potomac Landing, Allenwood, Owens Road, Deerfield Run and Seabrook elementary schools, DuVal and Suitland high schools, and Cheltenham Vocational School. All except DuVal are expected to be open today, according to a school spokesman.

MONTGOMERY COUNTY -- Carderock Springs Elementary School and Gaithersburg and Einstein high schools. School officials expected all three to be open normally today.

ANNE ARUNDEL COUNTY -- Hillsmere and Lothian elementary schools and Southern Middle School. School officials say all three should be open normally today.

HOWARD COUNTY -- Waterloo Middle School. Officials expect the school to be open today.