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Manual J, S, D, N

Manuals J, S, D, & N

Manuals J, S, D, & N with Marrs HVACR Design

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The actions you take when constructing a new home will have lasting effects on the efficiency, performance, and comfort of the home over the course of the building's existence. This is why it’s important that all HVAC systems are properly designed up front, to prevent any expensive issues for your clients down the road. There are loads of things to consider and manage when constructing the HVAC system for that new building!


However, when it comes to HVAC Calculations by the book, you can rely on Marrs HVACR Design to get the job done right the first time; your clients will thank you when they see how efficient their systems are and how sublimely comfortable their homes, businesses, or office spaces are.


Whether you’re working on residential or commercial buildings, large or small companies, you need mechanical designers you can trust to ensure your Manual J, S, D, & N calculations are completed in a timely manner. In this way, you gain the opportunity to grow your business and get those crucial plans to your clients at a much faster rate.

Marrs HVAC services manual J,D,S,N

Overview of Manual J, S, D, & N

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Developed by the ACCA (Air Conditioning Contractors of America), Manuals J, S, D, & N are standards and protocols used by contractors to properly design a fully optimized HVAC system in new homes or businesses. It ensures all equipment is personalized for each building, mainly to ensure appropriate sizing and equipment selection. Working together, these calculations ensure you have the correct equipment, properly installed with effective ductwork, ensuring the home is heated and cooled evenly and efficiently.


Without these crucial calculations, you can expect a variety of issues; higher energy bills, uneven cooling, ineffective air flow, high humidity and stagnant air, and lower levels of comfort. Marrs HVACR Design has 25+ years of experience working these manuals; you can rely on us to ensure your home’s HVAC system is designed to provide the absolute ideal outcomes. There are entire books on each of these manuals and trust us; we’ve done our research so you don’t have to!

  • Manual J

    This is for Residential Load Calculation. The most popular of manuals arguably the most important, this allows contractors and homeowners to accurately determine the total amount of heat lost outdoors in cooler months and the total amount of heat gained in the home during warmer months. It takes into account the characteristics of the home, such as insulation, walls, square footage, number of windows and doors, and more. It also accounts for climate, existing ductwork leakage, air envelope tightness, and more.

  • Manual S

    This is Residential Equipment Selection. Following Manual J, this calculation helps us understand why and how we should select equipment based on load calculations in accordance with the AHRI and ACCA. It takes in account how your equipment will function in your specific environment, at lower and higher altitudes of varying outside temperatures and humidities. We’ll ensure your equipment has the appropriate BTUs and SEER ratings (air conditioning), AFUE ratings (furnace), and HSP ratings (heat pump) for your home’s specific needs.

  • Manual D

    On to Step 3; Duct Design! Whether you’re replacing an old, worn down duct system, or building a new home, duct design is crucial to avoiding unnecessary energy expenses, uneven cooling throughout the home, and a noisy HVAC system. You’ll need properly sized ductwork and strategic placement of return grills and supply plenum to avoid these outcomes! They’re based on Manual J calculations (see, manual J is very important!) and your home’s floor plan. Your main room will need more air supply while your bathroom will need less; this is what Manual D can do for you.

  • Manual N

    These are for our companies and corporations; Commercial Load Calculations. This is how your contractors will meet those complicated HVAC code requirements for your new commercial building. It will include material, assembly, and operation necessities so your business can operate safely and efficiently. With Manual N, you can rest easy knowing your equipment is properly sized for your building; too big or too small, and you’ll be facing high energy costs and a very warm summer indoors!

Take the Stress Away with a Marrs Prepared Manual J

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Having a correctly sized heating and cooling system for your home is absolutely imperative to ensuring you and your family’s comfort during warm summer months, and keeping your monthly energy costs low. More than that, a proper load calculation, performed in accordance with the Manual J 8th Edition procedure, is often required by national building codes, state and local jurisdictions.


As a architect, engineer, general contractor, HVAC contractor, or a homeowner, this can be quite an overwhelming and confusing process. However, it’s necessary to both meet code and ensure your home is operating a peak efficiency. There are so many benefits of using Manual J load calculations. Namely, it ensures your unit can keep your home at the desired, comfortable temperature we take for granted too often. It will also ensure you don’t fall victim to short cycling, an incredibly expensive symptom of an improperly sized system.

comfortable family with proper manual j,d,s,n

As a contractor, this is a great opportunity to take the stress of building a new home away from your client. On average, our Manual J calculations take anywhere from 3 to 4 business days. However, we offer two great services at an additional charge for busy contractors looking to grow their business and homeowners in a time crunch.

  • Same Day before 5PM: If you send your measurements and other information over to us, before noon eastern time, and you'll have it by end of business same day (5 o'clock eastern time). Contact us for Same Day before 5pm pricing
  • 24 Hr. Turn-around: If you send your measurements and other information over to us, before noon eastern time, you'll have it within 24 hours. It’s that easy! Contact us for 24 Hr. Turn-around pricing.

Click here to learn more about our HVACR Design Partnership. This is an excellent opportunity for you to grow your HVAC, contracting, or engineering business and provide better service to your clients. This unique offer is a subscription that decreases completion times to 2 business days, and gives Priority HVACR Design Consulting when needed.

Take Guesswork Out of HVAC Design with Marrs

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Marrs HVAC Design is your perfect connection for outsourcing your engineering department. Here are a few reasons why Marrs HVAC Design should be your go-to for all things ACCA Manual J, S, D, & N.

  • Timeliness: We recognize that sometimes things need to get done ASAP. Maybe you have so many clients, you just don’t have time to get the calculations done yourself! We can complete your Manual J calculations in 24-hours; think of how much you can grow your business with this asset in your tool box!
  • Professionalism: With 25+ years of experience, all of our certified technicians are ready to get your calculations, standards, and protocols completed in the most accurate and efficient manner possible.
  • High-Quality Services: It’s imperative to have a professional complete these calculations. Skip reading through ACCA books on Manuals J, S, D, & N, and let us do accurate, effective, and efficient HVAC design plans and calculations that will save you and your clients money for years down the road!
  • Honesty & Integrity: We are fully committed to your success as a homeowner or as a contractor. We achieve this by maintaining our 3 key principles in everything that we do; giving you a quality product, at a valued price, while performing optimum customer service.

Get Your ACCA Compliant HVAC Calculations

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If you’re building a new home or commercial building, or revamping your building’s current, old, worn-down HVAC system, give us a call! We’re happy to provide accurate, effective, and long-lasting HVAC Design plans and calculations to ensure your home or business’s systems are working at peak efficiency for years to come. Contact us today or schedule an appointment online today and take the first step to a more efficient home!

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