City councilors voted unanimously Monday night to enter long-term lease and loan agreements with Duane Hallowell, president and chief executive officer of Hallowell International LLC. Hallowell is converting a city-owned building at 110 Hildreth St. into a manufacturing, assembly and distribution facility for heat pumps, devices that can extract heat from air as cold as 30 degrees below zero. The operation ultimately could create as many as 900 jobs, Hallowell said last August. In order to become eligible for the long-term lease, purchase option and $200,000 business development loan, the entrepreneur had to raise at least $1.5 million in financing and hire at least four employees. According to city documents, Hallowell must apply half the loan to his lease payments.