Miami-Dade Mayor Carlos Gimenez named a new county fire chief Thursday, the same day current chief William “Shorty” Bryson announced his retirement.

Dave Downey, an assistant fire chief in charge of operations, will take the helm of the largest fire department in the Southeast on Feb. 2. Bryson’s retirement, which was expected, takes effect Feb. 1.

Downey, 49, a Fort Lauderdale native who became a firefighter for the city of Sunrise in 1982, has been with the county’s fire rescue department since 1988.

“I’ve enjoyed my 30 years in the fire service, and I think this is a natural progression,” he said. But, he added, “This is not something I had planned for.”

Gimenez appointed Bryson, a longtime, trusted friend, shortly after he became mayor in August 2011, with an eye on looming union negotiations.

“We had a lot of battles,” Gimenez recalled at a news conference Thursday. “I wanted to get somebody that was going to help me.”

Two months later, the county reached a tentative contract agreement with the firefighters’ union that avoided the steep cuts other bargaining units faced while offering savings by reducing overtime.

The mayor, a former firefighter and fire chief for the city of Miami, lavished praise on Bryson, 61, whom he has known since the two joined the city’s fire department in 1975. Bryson was the fire chief when Gimenez was the city manager; when Gimenez was elected county mayor, he brought Bryson out of retirement to seek the union concessions and streamline the department, which has a budget of about $370 million and nearly 2,500 employees.

This time around, Gimenez said he wanted to elevate someone from inside the department to the chief’s job. He tasked Bryson to groom his successor.

The mayor touted Downey’s years of service, experience teaching public safety courses at local universities and involvement in the Federal Emergency Management Agency’s urban search-and-rescue program. Downey’s new salary has not yet been set. His current salary is about $164,000; Bryson’s salary was $185,000. Downey’s appointment must still be approved by the county commission.

Downey said he hopes to lower response times across the county and step up service, particularly in neighborhoods in northeastern, western and southern Miami-Dade.

“As our tax base increases, we still have a lot of areas of the county that are underserved,” he told The Miami Herald.

Rowan Taylor, president of the International Association of Firefighters Local 1403, gave high marks to Bryson, saying he was able to resolve union grievances. The number of new grievances filed has also gone down, Taylor said.

And the rank-and-file is pleased that the new chief is being promoted from within the department.

“He is someone who has worked his way through the ranks up to assistant chief and now fire chief,” he said. “We’ve had a good working relationship with him.”

Gimenez has yet to name a successor for former Miami-Dade Police Director James Loftus, who retired early last August. Gimenez acknowledged that it has taken him longer to make that decision, and said he had expected Loftus to stay longer.

“He kind of left a little bit before we thought he was going to leave,” he said.

The department is being overseen by assistant police director J.D. Patterson.

A previous version of this article mistakenly said the police department was also being overseen by assistant police director Naim Erched. He retired earlier this month.