Frank B. Cullen was originally employed with Medallion Industries in Bowie, Maryland at the age of 18. He was a sheet metal mechanic specializing in heating and air conditioning work that carried over in to HVAC engineering at several buildings. Then, in 1986, Frank and his father, Dennis Cullen, established Frank Cullen Inc. that specialized in HVAC service with old fashioned values. The company will be passed down to his son Michael Cullen and will carry on for years to come.