Our Story & History

Founded in 1977, William G. Day Company began as a small, local plumbing and HVAC service in Wilmington, Delaware. After years of dedication, Brian and JoAnne Marcocci, who worked for the original owners, transitioned into ownership in 2023-continuing the company's long-standing tradition of integrity and quality.

Milestone progression: Over the decades, WGD grew into both a residential and commercial full-service plumbing and HVAC Contractor that is a Certified Factory Authorized Carrier Dealer (CFAD), and earned an A+ BBB rating, cementing its reputation in Delaware and surrounding areas of Eastern Maryland and Southeastern Pennsylvania.

Challenges & growth: From adapting to new HVAC technologies and changing regulations to meeting rising customer expectations, the company has stayed resilient-investing in training and certifications to keep delivering reliable service.

Evolution: Today, WGD offers complete solutions: from air conditioning, gas furnaces, and heat pumps to indoor air quality, and all aspects of plumbing services.

Founding story: Built on a foundation of trust, craftsmanship, and community respect, the company remains family-driven in spirit and service.

Our Team

Owners & leadership: Now led by Brian and JoAnne Marcocci, whose journey from employees to owners shows their dedication and deep understanding of the business.

  • Family & staff: Two of their sons work in the company alongside a talented team of 14 other experienced staff members-bringing together years of hands-on expertise and customer-first service.
  • Culture & motivation: The team prides itself on honesty, respect, and quality work-not high-pressure sales-creating a welcoming, professional experience for every customer.
  • Trust & credibility: Nearly five decades of service, CFAD certification, and an A+ BBB rating underscore the company's commitment to doing the right thing, every time.

Our Impact & Offerings

Who we serve: Homeowners and commercial clients across Delaware, Eastern Maryland, and Southeastern Pennsylvania looking for reliable, long-term HVAC and plumbing solutions.

  • Services: - HVAC installation, repair, and maintenance (including furnaces, AC, and heat pumps) - Plumbing repairs, water heater services, and Indoor air quality solutions.
  • Customer benefits: - Free estimates for installation of new equipment - Emergency service when you need it - Flexible financing and clear, pressure-free advice
  • Approach: Combining certified technical expertise with a commitment to honesty and respect-ensuring comfort, efficiency, and peace of mind for every client.

Community & Future

Local engagement: Proudly rooted in the Wilmington area, WGD has become a trusted name through word of mouth, online reviews, and community relationships.

Future vision: Continuing to invest in advanced technologies, preventive maintenance programs, and customer-focused innovations.

Legacy: To remain a reliable partner for generations to come-trusted for our values as much as our technical skill.