Myers, who has been a starter in all but one of his 10 years in the Major Leagues, is being moved into the closer role. He closed for the Phillies in 2007, but was moved into that role after starting the season in the rotation.
Astros manager Brad Mills would like to see Myers throw back-to-back days, but not right away.
"We're going to see how he throws and try to build him up," he said. "I don't know if we'll throw him three days in a row, but I'd like to get back-to-back with him at least twice. He'll throw at least three times a week moving forward."
Myers, who has thrown the fifth-most innings in the National League the past two years, was 5-5 with 21 saves and a 2.87 ERA in 48 relief appearances with the Phillies in 2007. He was moved back to the rotation after the Phillies acquired Brad Lidge from the Astros.