About hvacloadcalc.org

What the Site Is

hvacloadcalc.org is an independent educational reference covering residential HVAC sizing, the ACCA Manual J / S / D / T design methodology, heat pump systems, AC and furnace selection, ductwork, and the building science that drives load calculation. The site is built to help homeowners level up from "I have no idea what my contractor is talking about" to "I can verify whether this quote makes sense."

The content is organized into four layers:

• 11 reference hubs — heat pump, AC, furnace, Manual J, Manual S, Manual D, Manual T, building science, tools, and HVAC glossary.
• 15 in-depth articles on specific topics: heat pump aux heat, defrost cycle, SPF, sizing, AC short cycling, Manual J, wet bulb temperature, attic R-value, window U-factor, HERS Index, return air sizing, mini-split sizing, Manual J verification, aux heat meaning, AC BTU chart.
• Five live calculators with 61 worked-example URLs.
• Supporting site identity, legal, and methodology pages.

Every article opens with primary-source citations (KeyTakeaways summary), continues with data-table-heavy reference content (no walls of prose), and ends with a FAQ section and a sourced bibliography. Articles are designed to be quote-extractable in isolation: a research assistant or LLM pulling a specific fact out of context should find a sourced, defensible statement.

Audience and Intent

The site serves four overlapping reader groups.

The primary audience is homeowners. Other reader groups are served by depth that already serves homeowners well — methodology, real-data reference tables, and primary-source citations matter to all four groups. The tone across the site is technical but accessible: readers should level up, not be talked down to.

The reading level target is high-school-to-college-educated, with willingness to engage technical detail when it is well explained. Articles are paced for skim-readability (every paragraph followed by a non-prose block), with optional depth available for readers who want it. The structure is designed for both linear reading and targeted Q&A extraction.

Editorial Mission

The HVAC reference space online is structurally broken in three ways.

Calculator sites (Calculator.net, Omnicalculator, MiniWebtool) use rule-of-thumb math marketed as Manual J. They produce numbers with no documented methodology, no sources, and no acknowledgment of uncertainty. The output is misleading to homeowners who think they have a sizing answer when they have a square-footage-times-a-constant guess.

Contractor-software sites (Cool Calc, AutoHVAC, ServiceTitan, Conduit) are built for HVAC professionals, paywalled, and homeowner-hostile. They typically require account creation, B2B subscription, or contractor verification to access. The methodology is appropriate; the access model is not aligned with homeowner research needs.

Manufacturer sites (Trane, Carrier, Lennox, Mitsubishi, Daikin) carry built-in bias toward their own equipment. Even when their content is technically accurate, the framing pushes toward purchase decisions favoring the manufacturer. They are useful for equipment-specific data; they are not useful for objective comparative research.

The editorial mission has four explicit pillars: (1) deeper than competitors (full Manual J / S / D / T methodology, not rule-of-thumb), (2) cleaner than competitors (no clutter, fast page loads, mobile-first design, no friction), (3) more authoritative (every claim sourced, every calculation transparent), and (4) more useful (real data tables, calculators with documented methodology, worked examples for common queries).

Independence

The site is independent of every commercial party in the residential HVAC ecosystem cited across its content. We cite ACCA, ASHRAE, AHRI, NEEP, NFRC, RESNET, DOE, EPA, IRS, EIA, and dozens of other primary publications as authoritative sources for the methodology behind every article and calculator. We have no operational relationships with any of them — no membership for the editorial team, no advisory roles, no co-marketing.

We also have no commercial relationships with the equipment manufacturers (Trane, Carrier, Lennox, Mitsubishi, Daikin, and others) whose products are discussed in equipment hubs. References to specific manufacturers in articles are because their products dominate market categories or because their published spec sheets are useful reference material — not because of any business arrangement.

We have no relationships with HVAC contractors or installers. The site does not maintain a contractor directory, does not match readers to installers, and does not participate in any contractor referral arrangements. Where the content discusses how to evaluate or work with contractors, the framing is reader-to-contractor relationship, not a contractor-to-site relationship.

We have no relationships with HVAC software vendors (Wrightsoft, Elite, Cool Calc, EnergyGauge). These tools are mentioned in the tools hub as the appropriate solution for permit-grade Manual J work; the mention is editorial context.

The full editorial process, including how potential conflicts of interest are disclosed and how reader feedback drives corrections, is documented at /editorial-standards/.

What the Site Is Not

To be explicit about scope.

The site is not an HVAC contractor or installer. We do not perform installations, sell equipment, or provide on-site consultation. References to contractors throughout the site are about how to work with contractors, not how to find them.

The site is not a licensed professional engineering service. The site does not provide engineering services; the calculators produce planning-grade output appropriate for understanding magnitudes, not permit-grade output appropriate for regulatory submissions. The methodology page explains the difference in detail.

The site is not ACCA-approved. ACCA approval applies to permit-grade Manual J software (Wrightsoft, Elite, Cool Calc, EnergyGauge). Our calculators are not on the approved list, and we do not seek to be — the certification fees and process are appropriate for commercial software vendors, not free educational tools.

The site is not a contractor directory or installer match service. The site does not maintain lists of HVAC contractors by region, does not match readers to installers, and email goes to a single editorial inbox rather than to any contractor distribution.

The site is not a repair-tutorial source. We explain concepts and methodology; we do not provide step-by-step instructions for safety-critical repair work (refrigerant handling, electrical work, gas connections). Where readers need that level of detail, the right answer is hiring a licensed contractor.

Technical Approach

The site is built on a deliberately conservative technical stack chosen for performance, reliability, and search-engine indexability.

The calculator architecture pairs an interactive widget (client-side React) with a server-side worked-example default state that shows the math before any input is changed. Common configurations (e.g., "1500-sq-ft-zone-5") render as separate URLs with pre-computed output and a step-by-step explanation, so each frequent question has its own complete answer.

The architecture is documented in detail at /methodology/ and /tools/. The source code is in a public git repository.

Editorial Process Summary

The editorial process is documented in detail at /editorial-standards/. Summary:

1. Every article starts from a detailed brief specifying topic, content scope, source list, internal links, and SVG asset requirements. Briefs are checked into the repository at /content/briefs/.

2. Every numeric claim is sourced inline to a primary source via the SourceCite component. Bare numbers in prose without inline citation are prohibited by the editorial standards.

3. Every calculator's methodology is documented openly with source citations, accuracy claims against ACCA reference cases, and known limitations enumerated.

4. Every article gets an annual review against current standards. Material methodology changes are logged at /corrections/ with the original claim, the corrected claim, the date, and (with permission) the reporter.

5. Errors get fixed promptly. Methodology disagreements get evaluated and either resolved or documented as ongoing reasonable-practitioner debates.

The editorial mission is durability: content should be accurate when written, remain accurate as standards change (via update cycles), and remain useful 5-10 years after publication. The depth of source citation makes that possible — every claim can be re-verified against its original source at any time.

How to Reach the Site

The site has a single contact channel: the contact page at /contact/. The form accepts general inquiries, methodology questions, correction reports, and accessibility feedback.

Correction reports are the highest-priority category. We acknowledge all methodology corrections within 14 days. Material corrections are logged at /corrections/ with the original claim, the corrected claim, the date of correction, and (with the reporter's explicit consent) attribution.

We do not provide individual sizing consultations by email. The calculators on the site are designed to answer planning-grade sizing questions; for specific equipment selection in a specific home with permit-grade liability, a credentialed party should be engaged.

We do not provide brand or contractor recommendations for specific homes. Equipment selection depends on local conditions (climate, envelope, electricity and gas prices, contractor availability) the site cannot evaluate. The content points at authoritative product lists (ENERGY STAR Most Efficient, NEEP CCASHP product list, AHRI Directory) where qualifying models are independently verified.