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HVAC Design for Homeowners

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    No two projects are identical, so we don't offer a preset price quote. If a quote doesn't change based on your actual plans, it's worth asking what happens once your project turns out to need more time than that quote assumed. Every project gets a preliminary plan evaluation before your consultation, to confirm the architecture has room for a proper, real-world duct and airflow layout. Your free consultation is a chance to walk through your project, ask questions, and find out exactly what we'll need from you to get started.

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    What Our Customers Say

    I knew I needed new ductwork and that I would need to buy a new unit in the next few years. To avoid getting swindled, I decided to get unbiased information from a consultant who would not be selling me equipment. David Brown and ConsultAir came highly recommended and I have not been disappointed. David created Manual J, S and D reports and a duct system layout, with quick replies that include thorough and easy-to-understand answers. As I gathered my first quotes from HVAC contractors, I got pushback on using a consultant’s drawings – some refused, others offered elaborate sales routines and scare tactics to persuade me to use their own drawings and equipment instead. I contacted David with questions about what I was experiencing, and he confirmed my suspicions about one contractor and offered additional guidance so I felt fully armed going into additional quotes.

    SM Axland – via Google Review

    If you are thinking of doing any kind of heating or cooling in your home don’t take a chance by trusting the local HVAC person. They have one agenda… To sell you an overpriced system and get the job done as quickly as possible. I learned this because I had 5 different bids and 5 different sized systems from each installer. How could this be I wondered? Well…it turns out that there is a real, systemic, and calculated way of finding out how big of a system you need for your home. There are manuals and load calculations that can be done to properly size your system. After much searching on Google I stumbled upon David Brown and ConsultAir. He was the person I was searching for. He did all the load calculations, the calculations for the ductwork and even offered some very helpful tips along the way. David should be your first call when looking to install a system. I cannot recommend him highly enough. Thanks David!!!

    Timothy McNeely – Bakersfield, California

    So, I'll start by saying I almost never write reviews. I know I know... it's a good, neighborly thing to do but for whatever reason, I don't ever seem to get around to it. That said, with respect to David and ConsultAir, it's more than warranted. Plainly put, if I could somehow magically reach out to anyone dealing with HVAC issues, I'd tell them this... he is one of the nicest, most helpful, most KNOWLEDGEABLE people I've ever met. And, at this point, the thought of installing or overhauling any HVAC system without his input seems ridiculous to me. My wife and I contacted David after (and here comes the all-too-common contractor story) our HVAC contractor installed a system in our house that was more than twice as big as it should have been. Three units powering different zones of the house, all oversized, that led to freezing up and leaking into our ceilings, jet-like air delivery from the vents, wildly varying hot/cold spots, etc. At David's direction, we took detailed measurements and gave him an overview of what we needed. From minute one, he took an academic approach to our needs the original contractor SHOULD have... calculating the proper loads room by room, studying the layout/functionality of our existing system, and ultimately, reconfiguring/designing a system that worked efficiently. That last point is the most important... for having gone through a full remodel of our house, we've learned that designing a NEW system that works well (any type... HVAC, plumbing, etc.) is hard enough. Reconfiguring an EXISTING system to maximize its potential with the lowest additional cost... that's truly a step above. Because you're working with something that, oftentimes, is less-than-perfect to begin with. And, in our case... far from it. So, to wrap up what, at this point, has become a novel... we can't recommend David and ConsultAir highly enough. He saw us through a difficult situation in a way we've rarely encountered elsewhere, and if you're considering any sort of HVAC install... TALK TO HIM FIRST. You won't regret it.

    Gavin M. – Kingston Springs, Tennessee

HVAC Design Services for Homeowners – Sized Right From the Start

Choosing the right heating and air conditioning system for your home starts long before installation day. ConsultAir provides independent residential HVAC design services for homeowners nationwide, with particular depth in custom new-construction projects, built on ACCA’s Manual J, Manual S, and Manual D standards, the same calculations most current building codes require. Getting this right in advance is the best way to reliably meet your comfort, performance, and investment expectations for years to come.

ConsultAir has spent over a decade focused exclusively on independent residential HVAC design, backed by decades of hands-on field experience. Learn more about ConsultAir’s background on the About Us page.

Is bigger always better when it comes to a heating and air conditioning system?

Bright, comfortable living room in a custom home with a properly sized HVAC system

Most of the problems with an oversized system trace back to one root cause: “short cycling,” when the system turns on and off too frequently without completing a full cooling or heating cycle. A properly sized system typically needs to run for a minimum of 15 to 20 minutes to reach its correct refrigerant operating pressures and condition your home evenly. An oversized system shuts down after just a few minutes instead, only to turn back on again shortly after. This typically leads to:

  • Poor humidity control, leaving the home feeling cool but clammy
  • Noticeable temperature differentials from one room to another
  • Shortened equipment lifespan from excess wear due to repeated starting and stopping
  • Higher energy bills
  • Increased maintenance and repairs over time
  • Increased noise
  • Higher upfront installation cost
  • Reduced peace of mind, knowing your system isn’t performing as well as it should

Modern variable-speed compressors can modulate their output instead of cycling fully on and off, which meaningfully reduces many of these issues.

Proper HVAC design for homeowners starts with knowing your system is sized correctly. Thousands of homeowners each year specifically request, or unknowingly pay, to have an oversized HVAC system installed in their home. A Manual J load calculation, along with Manual S equipment sizing, determines what size heating and air conditioning system is needed to provide you with maximum comfort and energy efficiency.

What’s Included in a ConsultAir HVAC Design

  • A room-by-room Manual J load calculation report
  • Manual S equipment sizing recommendations
  • A to-scale Manual D duct design drawing showing duct routes and sizes
  • One block of up to an hour for revisions before your duct system is installed

See a complete example in the Sample HVAC Design Package.

Frequently Asked Questions About HVAC Design for Homeowners

  • Won't a larger heating and air conditioning system run less and therefore reduce my utility bills?

    Here’s a simple way to understand how an oversized system can result in higher monthly utility bills. Consider your HVAC system’s operating efficiency the same way you’d think about a car’s miles per gallon (MPG).

    Your car may get 35 MPG on the highway, but in city driving, it might only get 28 MPG, because constantly stopping and accelerating takes far more fuel than maintaining a steady speed. Your air conditioner or heat pump works similarly: its SEER rating (now called SEER2 on new equipment) reflects peak, steady-state efficiency, but there’s no “city MPG” rating for HVAC equipment. An oversized system may never reach its advertised SEER in practice, because it shuts off before completing a full cycle. A properly sized system typically needs to run for a minimum of 15 to 20 minutes to reach its correct operating pressures, so a unit rated at 15 SEER that only runs for a few minutes at a time before cycling off may perform closer to 10 SEER in real-world use.

    This same short-cycling penalty applies to gas furnaces, though the consequences are generally less significant than with an oversized air conditioner or heat pump. A furnace’s efficiency is measured by AFUE rather than SEER, and since heating doesn’t carry the added job of removing humidity from the air, an oversized furnace mainly costs you in wasted fuel and added wear rather than the comfort and humidity problems associated with an oversized cooling system.

    Just as compressors come in single-stage, two-stage, and variable-speed configurations, gas furnaces use single-stage, two-stage, or fully modulating gas valves. Two-stage and modulating equipment, on either the cooling or heating side, can meaningfully reduce short-cycling penalties by running at a lower output for longer periods instead of cycling fully on and off.

  • Can a remote HVAC design handle the extreme weather where I live?

    Yes. ConsultAir’s residential HVAC designs are based on recorded weather and climate data for your specific location, not assumptions or regional guesswork. Manual J sizes your system for your area’s design conditions, the hottest and coldest temperatures your location reaches or exceeds only about 1% of the hours in a year, along with local humidity and elevation. In other words, your design is built for the full range of conditions your climate normally sees, not just its averages.

  • Shouldn't I use a local HVAC designer, or one closer to my project site?

    Not necessarily. HVAC design work is created based on the specific recorded climate data where your project is located and directly from architectural and structural/framing plans, not from standing on site. Even if your home construction project has already been fully framed, designing the system from the plans is by far the most practical approach, since the design process itself relies on a desktop computer and specialized software, not a physical walkthrough.

    The exception is retrofitting ductwork into an existing home’s framing, since these projects rarely come with accurate as-built plans to design from. In these cases, working with a competent local HVAC contractor who implements proper design methods before installation is typically more feasible. Full renovations with adequate architectural and structural plans are a different story, and are handled the same way as new construction.

    ConsultAir works with homeowners, home builders, and HVAC contractors nationwide for exactly this reason: plans and project information are shared digitally, so your project gets a properly designed Manual J, S, and D package regardless of where you or your project are located.

  • Does my duct system need to be designed too?

    A perfectly sized heating and air conditioning system is only as good as the duct system that it is connected to. This is why the Air Conditioning Contractors of America (ACCA) created Manual D.

    A duct system that is designed to Manual D standards is going to quietly distribute the correct amount of air to each room. ConsultAir’s Manual D duct design includes a to-scale drawing of the duct routes and sizes to be installed.

  • Why can't I do my own Manual J load calculation?

    You can try, but a load calculation is only as accurate as its inputs. Free calculators and spreadsheets range from old-school rules of thumb, like 500 square feet per ton, to full Manual J tools, and even the best software gives the wrong answer when window ratings, insulation, orientation, or duct locations are entered incorrectly. Building departments, along with many energy efficiency rebates and incentives, expect a load calculation that follows ACCA’s Manual J standard, and the results feed directly into Manual S equipment sizing and Manual D duct design. ConsultAir uses only ACCA-approved Wrightsoft HVAC design software, backed by decades of hands-on field experience in knowing which inputs matter most.

    Current editions of the International Residential Code, which most states have adopted, require heating and cooling equipment to be sized using ACCA Manual J and Manual S.

  • How do I place my order to have my HVAC system designed?

    Getting started with your residential HVAC design is easier than you might think. See the “How It Works” box on this page for exactly what we’ll need from you, our turnaround options, and what you’ll receive.

  • What if something changes after my HVAC design is delivered?

    Ideally, your architectural and structural/framing plans are finalized, and your preliminary specifications, like window performance ratings and insulation types, are decided before your HVAC design begins. Whether you’re building the home yourself or making those decisions alongside your builder, plans and choices sometimes change along the way. That’s why every ConsultAir design includes one block of up to an hour for revisions after your design is delivered, at no extra cost. Simply keep a list of any changes as they come up, and send it along with a marked-up duct plan (if needed) a few weeks before your duct system is scheduled to be installed. ConsultAir will revise the design and deliver a complete, updated set of as-built plans and reports.

  • Should I keep a copy of my HVAC design after installation?

    Yes, and it’s worth filing away with your other important home documents. Beyond helping with future remodels or duct work, it’s a genuine selling point at resale: being able to tell a buyer your system was professionally sized and documented, not installed by rule of thumb, adds real peace of mind. And if a buyer’s inspector or contractor wants to look closer, your Manual J, S & D package is there as actual proof, not just a claim.

Free HVAC Design Consultation for Homeowners

How It Works

“By allowing ConsultAir design my new system, I was able to give the local air conditioning contractors all of the information they needed, including ‘to scale’ duct drawings, which allowed me to compare ‘apples to apples’ as I reviewed the different proposals that I received. Since then, my electric bills are lower and the ‘hot spots’ in my house are gone.”

Richard P Malinis – Jacksonville, Florida

A properly designed HVAC system, backed by Manual J, Manual S, and Manual D, protects more than your comfort. It also protects your energy bills, your equipment’s lifespan, and your home’s value when it’s time to sell.

Get a heating and cooling system that’s sized right from the start. Order your Manual J, S & D HVAC design today for lasting comfort, efficiency, and fewer surprises down the road.

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HVAC Rebates, Codes & Industry Resources

Rebates, tax credits, and trusted resources to help you plan your next HVAC project with confidence.

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