From Humble Beginnings to Leading Expertise
Founded in 2008 by Gary Cullum, G. Cullum Heating & Cooling is family-owned and operated. Growing up in Darlington, MD, Gary began working at 16 years old for his dad at Dublin Heating & Air, beginning his experience in HVAC. After 20 years of installing Lennox equipment at Dublin, Gary decided to move to Rising Sun to work for a company in Oxford, PA. During that time, Gary began slowly gaining customers. In 2008, Gary took the leap and started his own business, working out of his own basement. G. Cullum Heating & Cooling was officially born. From 2008 to 2014, Gary continued working out of his home and slowly gained more and more customers. In 2014, he purchased the existing property off Biggs Hwy in Rising Sun, and since then G. Cullum has grown to over 3,000 customers in the Cecil, Harford, Chester, and New Castle County areas.
I’ve been in business for myself since 2010 and have serviced the tristate area for over 40 years. I am committed to providing your home with exactly what it needs to be efficient and effective at heating and cooling your home.
- Gary (Owner)
Meet Our Team
Gary Cullum
President & Owner
Gary began working at 16 years old for his dad at Dublin Heating & Air, beginning his experience in HVAC. After 20 years of installing Lennox equipment at Dublin, Gary took the leap and started his own business.
Joey Cullum
Project Manager
Joey joined his dad in 2014, at the expansion of the company. He wears many hats, including sales, part ordering, inventory control, and overseeing things in the office to run smoothly. In his free time, Joey enjoys hunting, fishing, and anything outdoor-related. He also enjoys spending time with his family and girlfriend.
Gary Muehlberger
Service Technician
Gary recently joined our team in February of 2025. With his years of knowledge in the HVAC field, Gary has been a big help to our team. When he is not at work, Gary enjoys spending time with his daughter.
Jordan Balog
Senior Install Crew Leader
Chances are, if we have installed a system for you, then you have met Mike. Mike joined Gary in the beginning of G. Cullum has been here since. With his hard work and dedication, he has helped Gary grow tremendously over the years. In his free time, he enjoys riding motorcycles, mountain biking, and spending time with his two kids and wife.
Michael Goss
Operations Manager
Chances are, if we have installed a system for you, then you have met Mike. Mike joined Gary in the beginning of G. Cullum has been here since. With his hard work and dedication, he has helped Gary grow tremendously over the years. In his free time, he enjoys riding motorcycles, mountain biking, and spending time with his two kids and wife.
Ethen Oakley
Service Technician
Karrie Strickland
Office Manager
Karrie recently joined our team in March of 2025. She has already been a huge asset to our team, helping with our daily office operations. When Karrie is not at work, she is spending time with her family or tending to her farm.
Tori Hartnett
Office Administrator

Discover the difference 40 years of experience makes. Call (410) 658-9775 today to connect with G. Cullum Heating & Cooling in Rising Sun, MD.
