Doing business in all 50 US States, Canada, The Bahamas, & Australia



Professional Design & Building Sciences

Servicing all 50 US States, Canada, The Bahamas and Australia

Marrs HVAC Services

Marrs HVAC Design, LLC, is one of the world’s leading international mechanical design companies. We provide premium HVAC design & training services to homeowners, HVAC businesses, general contractors, and engineers around the globe. If you’re looking for experience, quality, accuracy, & timeliness for your HVAC calculations and evaluations, Marrs HVAC design is here for you through all phases of the construction process.

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Marrs HVAC Services mechanical design

Why Marrs HVAC Design?

Marrs HVAC Designs leads the industry in effective HVAC system design and planning, performing at high levels for a variety of modern built structures including residential homes to commercial spaces.


Our priority is producing plans that guarantee high performance, energy saving, and environmental sustainability, saving our clients thousands of dollars annually on their energy costs. All our designs are performed adhering to ACCA industry standards.

  • Timeliness: You can rely on each of our experienced, certified, and highly-trained designers to deliver your calculations and complete your testing on time, every time. We understand the importance of your timeline, and are happy to offer Same-Day before 5pm and 24 hr. turn-around, though this principle applies to each of our services.
  • Commitment to Your Success: Our approach as one of the nation’s leading HVAC design companies is grounded in a deep dedication to prioritizing the needs and success of our clients; we aim to protect your valuable investment. We won’t feel comfortable that we’ve completed your plans and evaluations correctly unless our standards, developed over 20+ years, have been met.
  • Proactive & Adaptive: The leaders of Marrs HVAC Design have a combined 25+ years of experience. However, they aren’t set in their ways! Continual ongoing education and constant attention paid to the latest innovations in the industry allow us to solve problems using innovative solutions at all phases of the construction process.
  • Personalized Solutions: Whether you seek code compliance services, in-depth analysis of energy usage in your built environment, or comprehensive HVAC design for new construction, Marrs HVAC Services has a solution that will best fit your home or business’s energy efficiency needs. Our goal is to participate in your renovation or new build as a partner, participating as dedicated team members every step of the way.

Our Services

Blower Door & Duct Blaster Test

One of the biggest culprits of low performance and low comfortability in homes and businesses is air leakage caused by gaps, cracks, and poorly installed or decayed insulation throughout the building’s air envelope. You can utilize blower door testing and duct blaster testing as a tool to directly confront this issue, leading to lower energy bills, improved comfort, a reduced carbon footprint, while efficiently meeting your municipality’s code!

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Manual J, S, D, & N

There are many things to consider when installing a new HVAC system or revamping an old, worn-down system. From residential or commercial load calculations (Manual J, and Manual N, respectively), to equipment selections (Manual S), to ductwork design (Manual D), it can be overwhelming! Take the stress out of designing your next HVAC system and work with Marrs HVACR Design. We’ve been doing these calculations adhering to ACCA industry standards since 1999 and we’re excited to offer you our expertise!

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Become an HVACR Design Partner

Is providing load calculations, ductwork designs, and equipment selection documentation a regular part of operating your business? We offer a great subscription-based service for contractors that decreases completion times to 2 business days, and gives access to priority HVACR design consulting! Start saving time and money today as an HVACR Design Partner.

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HERS Energy Rating

HERS (Home Efficiency Rating System) Energy Rating is required by municipalities in most states and serves as an in-depth analysis of the home’s energy performance. Improving a HERS rating can raise your home’s market value, and our recommendations to architects, engineers, contractors, and HVAC companies will assist in increasing efficiency and lowering that score. A lower HERS Rating means improved health and safety, low energy costs, and environmental sustainability.

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HVAC Design Training

Are you a contractor who is ready to offer the ultimate HVACR design experience for your customers, catering to high-ticket clients? Are you looking to level up your business and reach new heights? Marrs HVAC Design Training is an affordable, easily accessible, & comprehensive learning opportunity, giving you the ability to be a one-stop-shop for all things HVAC for your clients. Learn from one of the leading mechanical design companies in the world with our HVACR Design Training.

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24 Hr. Turn around and Same-Day Manual J

Manual J load calculations involve a variety of different specifications, including square footage, measurements of windows and doors, existing ductwork, and more. With other HVAC design companies, you can expect your Manual J calculations to be done in two to three weeks; with Marrs HVAC Design and our innovative 24 hr. turn around and Same-Day Manual J offers, you can get them before 5pm or within 24 hrs. With Same-Day Manual J, if you send us your specifications and build forms before noon, we’ll have your Manual J to you before 5 o’clock EST same day!


If you send after noon, you can expect it before noon the next day. With our 24 hr. turn around, As a general contractor, engineer, or architect, this is an absolute game changer. You can grow your business and increase your profit margins by providing this service to your clients, saving them time and money. They will thank you when they experience the fresh, sublime comfort of their new or existing home and when their energy bills are lower than ever with our ACCA compliant Manual J calculations.

Innovative HVAC Design Services with Marrs HVAC Design

Take the first step towards a more energy efficient and comfortable residential home or commercial building with Marrs’ innovative HVAC design services. As one of the leading HVAC mechanical design companies in the world, our team of design experts is happy to offer you comprehensive, accurate, and time-efficient HVAC design services. Give us a call or schedule an appointment online today! 

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