F.A.Q.
Frequently Asked Questions — HVAC Load Calculations & Design Services
Frequently Asked Questions
Have questions about Manual J load calculations, duct design, permit requirements, or working with ProCalcs? Browse by topic below. For in-depth answers about a specific service, visit the relevant service page linked throughout.
About Our Services
A Manual J load calculation is the industry-standard method for sizing a residential HVAC system, developed by the Air Conditioning Contractors of America (ACCA). It calculates how much heating and cooling a home requires based on square footage, insulation, windows, local climate, and building orientation. Without it, systems are routinely oversized or undersized — causing higher energy bills and comfort problems. → Full details: procalcs.net/services/manual-j/
These are four separate ACCA standards that each cover a different part of HVAC design. Manual J calculates how much heating and cooling a home needs. Manual S uses those results to select the right equipment. Manual D designs the duct system to deliver conditioned air to each room. Manual N is the commercial equivalent of Manual J for non-residential buildings. Most permit offices require J, S, and D together for a complete residential submission. ProCalcs provides all four services nationwide.
Yes. In addition to ACCA Manual calculations, ProCalcs provides REScheck, COMcheck, California Title 24, and other state-specific energy compliance reports, often required alongside Manual J for permit submission.
Yes. Most permits require Manual J, Manual S, and Manual D together. ProCalcs delivers the complete package so you don't need to coordinate between multiple vendors. Energy compliance calculations are also available if required by your jurisdiction.
Turnaround Times & Process
Typical residential turnaround is 3–5 business days. Rush turnaround is also available. Commercial Manual N and full design packages (J ,S, D) vary by project complexity. Contact us with your deadline and we'll confirm what's possible.
To prepare an estimate, we typically need floor plans or a sketch with dimensions and the location and sizes of doors and windows. Once you're ready to move forward, we'll send you a Project Summary Form that captures all the details we need to deliver accurate calculations.
Yes. ProCalcs is fully remote and accepts digital file submissions in PDF, DWG, JPG, and most common formats. We serve all 50 states and there is no need to mail anything physical.
Fill out the quote request form on our website, email your plans directly to tom@procalcs.net, or use the chatbot to send them over. Make sure to include some project details and your deadline, and we'll respond with a quote — typically the same business day.
Pricing & Quotes
Pricing depends on project size and complexity. ProCalcs provides project-specific quotes, typically the same day you reach out. The quote you receive is the price you pay — no hidden fees.
Yes. Let us know which deliverables you need and we'll quote the full package together. Bundling is often more cost-effective and ensures all outputs are coordinated for permit approval.
Rush processing is available. Any rush fees are disclosed upfront in your quote before you commit.
Permits & Code Compliance
In most jurisdictions, yes. Manual J is required by the International Residential Code (IRC) and enforced by local building departments for new construction and many HVAC replacement projects. Requirements vary by state and county. → See also: procalcs.net/services/manual-j/
Many jurisdictions require it for replacement projects too, particularly when equipment size is changing. Some municipalities require it any time a permit is pulled for HVAC work. ProCalcs handles both new construction and replacement project documentation.
Rush processing is available. Any rush fees are disclosed upfront in your quote before you commit.
ProCalcs produces REScheck (residential IECC), COMcheck (commercial), California Title 24 compliance reports, and state-specific energy forms. Contact us with your jurisdiction and we'll confirm exactly what your project requires.
Who We Work With
Yes. HVAC contractors are among our most frequent clients. We provide permit-ready Manual J, S, and D calculations with fast turnaround so contractors can focus on installation without paperwork delays.
Absolutely. We regularly support builders and developers on production homes, custom builds, and multi-unit residential projects, including high-volume and multi-lot coordination.
Yes. Homeowners planning new construction, additions, or HVAC replacements are welcome to work with us directly. We'll explain what's needed and what to do with the deliverables. → See: procalcs.net/services/hvac-homeowners/
Yes. Architects and engineers use ProCalcs for the mechanical calculation component of their projects — Manual J, Manual N, and energy compliance — so they can focus on design while we handle load analysis. → See: procalcs.net/services/hvac-architects/
Yes. Energy raters, home performance consultants, and real estate professionals working on energy audits, green certifications, or compliance documentation use ProCalcs regularly. Reach out and describe your project if you're unsure whether it fits.
HVAC Glossary & Technical Terms
Frequently Asked Questions
Not sure what a technical term means? The glossary below defines common HVAC and energy calculation terminology found in Manual J reports, permit documents, and building science.
Measures the amount of fuel converted to space heat in proportion to the amount of fuel entering the furnace. This is commonly expressed as a percentage. A furnace with an AFUE of 90 could be said to be 90% efficient. AFUE includes any input energy required by the pilot light but does not include any electrical energy for fans or pumps.
Any material that restricts air flow. In wall assemblies, the exterior air barrier is often a combination of sheathing and either building paper, house wrap or board insulation. The interior air barrier is typically gypsum board.
Insulation that is typically manufactured out of fiberglass into ‘blankets’ sized for typical framing bays and manually fitted into place. They require extra diligence to ensure no gaps, voids, compression, or misalignment in framing bays that do not fit standard framing dimensions or include wiring and piping.
This diagnostic tool is designed to measure the airtightness of buildings and to help locate air leakage sites. The airtightness of a building is useful knowledge when trying to increase energy conservation or decrease indoor air pollution, or control building pressures.
Insulation typically made from fiberglass or cellulose that is blown into construction assemblies dry or wet that inherently fills the entire framed assembly to eliminate any gaps, voids, compression, or misalignment. Typically found in attics.
The outer shell, or the elements of a building, such as walls, floors, and ceilings, that enclose conditioned space. A vital piece in HVAC load calculations.
Insulation installation condition where the full thickness is reduced, resulting in increased density and reduced air pockets that drive thermal resistance. This undermines the effective R-value of the insulation.
The drawings (plans) and written specifications that describe construction requirements for a building. Our team works with contractors, designers, builders, engineers, and more to develop an ideal HVAC system for each project.
As used with thermal bypass, this refers to airflow that occurs in gaps between insulation and the air barrier due to temperature differences in and across the gap, resulting in a stack effect or driving forces from more to less heat.
A sealed ventilation system for combustion appliances that draws combustion air from outside the structure and vents combustion exhaust outside the structure. These systems may be combined with power vent exhausts. See Power Vent and Sealed Combustion.
Diagnostic tool designed to measure the airtightness of ductwork and to help locate air leakage sites. Duct leakage can increase heating and cooling costs over 30% and contribute to comfort, health, and safety problems. Our team specializes in Manual D duct designs.
A standardized measurement of the annual energy efficiency of water heating systems. It is the annual hot water energy delivered to a standard hot water load divided by the total annual purchased hot water energy input in consistent units. The resultant EF value is a percentage. EF is determined by a standardized U.S. Department of Energy (DOE) procedure.
The quantity of onsite electricity, gas, or other fuel required by the building equipment to satisfy the building’s heating, cooling, hot water, or other loads or any other service requirements (lighting, refrigeration, cooking, and so on).
A site inventory and descriptive record of features impacting the energy use in a building. This includes, but is not limited to: all building component descriptions (locations, areas, orientations, construction attributes, and energy transfer characteristics), all energy-using equipment and appliance descriptions (use, make, model, capacity, efficiency, and fuel type), and all energy features.
A home, certified by the U.S. Environmental Protection Agency (EPA), that is at least 30% more energy efficient than the minimum national standard for home energy efficiency as specified by the 1992 MEC, or as defined for specific states or regions. ENERGY STAR is a registered trademark of the EPA.
Ready to get started, or have questions? Contact us online to speak with our HVAC design team!
