Meet Our Diamond Certified Expert Contributor

Marcus Muller: Better Every Day

By Caitlyn Stair, Diamond Certified Research Reporter

Marcus Muller’s path to the HVAC industry began long before his career officially started. As a second-generation HVAC professional, he grew up around the trade and was influenced by his father’s work on the refrigeration side of the business. After finishing school, he faced a pivotal decision: pursue a traditional career path or step into the trades. “I had to choose between taking a marketing internship and doing what my dad did,” he recalls. “I decided to stay with HVAC and I’ve been doing it ever since.”

Over time, Marcus expanded his role beyond technician work, stepping into leadership positions that allowed him to impact teams and operations on a larger scale. Working on jobs and supporting HVAC companies across the United States, he gained a broad perspective on the industry and its regional nuances. His journey eventually led him to Hassler Heating & Air Conditioning, LLC, where he now serves as general manager. “When I was offered the position, I did my research and was surprised by how the Hassler name has been built in the Bay Area,” he says. “When you come across a brand with that type of reputation, you have to take the opportunity to help it grow.”

In his current role, Marcus focuses on delivering customized HVAC solutions that prioritize both performance and efficiency. From system design to installation, his team takes a highly tailored approach, ensuring every solution aligns with the homeowner’s specific needs. “We believe in partnering with our clients,” he affirms. “There’s no ‘one size fits all’ HVAC system—every home is different, so we build each one accordingly.”

Marcus says he’s driven by the opportunity to lead and develop people. “When you take on a general management role, you work for your team—they don’t work for you. I take pride in mentoring our staff and providing them with the tools and training they need to succeed. My goal is to help them get better every day.”

At the same time, Marcus remains deeply connected to the broader impact of the HVAC industry, particularly its role in energy conservation and innovation. “Everything today is about efficiency and conserving resources,” he notes. “That’s why we’re constantly evolving to create systems that use less energy while delivering better comfort.”

Originally from Brooklyn, New York, Marcus has lived and worked in numerous places throughout the country, which has given him a wide range of experience in different climates and markets. Now based in El Cerrito with his fiancée, Julie, and his son, Lawrence, he appreciates both the diversity and beauty of the East Bay. Outside of work, he prioritizes health and fitness, spending time in the gym as a way to stay grounded and maintain balance.

At the heart of Marcus’ professional approach is a mindset rooted in constant growth. “I try to get one percent better every day,” he says. “If you live that way, you’re never satisfied with the status quo—you’re always pushing to improve.”

Ask Me Anything!

Q: What’s the first thing you’d do if you could retire tomorrow?
A: I’d be on a plane to Hawaii or the Maldives. I love the beach.

Q: Do you have a favorite sports team?
A: I’m a New York guy, so I like the Yankees, Knicks and Jets. But I also appreciate the great teams in the Bay Area, like the Warriors and Giants.

Q: What’s your favorite type of music?
A: I like everything from Jimi Hendrix to old-school hip-hop to classical, especially Bach. I played multiple instruments growing up, so music has always been a big part of my life.

Q: What’s your favorite movie genre?
A: I like anything with mystery and depth, like sci-fi, spy thrillers and crime dramas.

Q: What are your favorite holidays?
A: Christmas and Thanksgiving. They’re family-focused and I get to enjoy some great food.