January 15, 2026
How to Handle Oversizing Without Getting Rejected
A contractor’s guide to calculating safe HVAC oversizing margins, justifying equipment selection, and maintaining AHJ approval using Load Calc Guru.
Load Calc Guru Blog
Manual J, HVAC Load Calculations, and Real-World Design
Deep dives on Manual J, HVAC load calculation software, heat pump sizing, duct design, and practical workflows for residential HVAC contractors.
January 8, 2026
Using Online HVAC Software to Speed Up Permit Approvals
A guide for contractors on using online HVAC software like Load Calc Guru to streamline Manual J, D, and S workflows and generate AHJ-ready reports.
December 30, 2025
Manual J and Manual S: Why They Must Be Done Together
Manual J determines the load, but Manual S verifies equipment performance. Learn why you need both for a compliant, comfortable design.
December 30, 2025
We Just Released Manual S — What That Means for Your HVAC Designs
Load Calc Guru now includes full ACCA Manual S equipment selection. Here’s what changed, why it matters, and how it protects your jobs from inspection failures.
December 28, 2025
Manual J for Remodels and Additions: Avoiding Common Mistakes
A guide for HVAC contractors on performing Manual J load calculations for remodels and additions using Load Calc Guru, while keeping AHJs satisfied.
December 22, 2025
White-Glove Load Calculation Service
Busy contractors or homeowners can rely on Load Calc Guru's white-glove service for accurate Manual J and Manual S reports.
December 20, 2025
Avoiding Load Calculation Errors in Residential HVAC Projects
A guide for contractors on common Manual J calculation mistakes and how to prevent them using Load Calc Guru for accurate, AHJ-ready reports.
December 20, 2025
Room-by-Room Load Calculations: Why AHJs Care
A detailed guide for HVAC contractors on why room-by-room load calculations are critical for Manual J compliance and AHJ approval, with Load Calc Guru tips.
December 18, 2025
Don't Oversize! 3 Mistakes HVAC Contractors Make
Oversizing HVAC equipment is a common mistake. Learn the three most frequent errors and how Load Calc Guru helps you avoid them.
December 12, 2025
Energy Code Compliance Without the Headache: A Contractor’s Guide
Tips for HVAC contractors to meet IECC and state energy code requirements during Manual J load calculations using Load Calc Guru.
December 10, 2025
One-Page Load Summary: The Secret to Faster AHJ Approval
How HVAC contractors can create a concise, scannable one-page load summary from Manual J calculations to streamline permit approvals using Load Calc Guru.
December 10, 2025
Why the Pro Plan is Worth It
Discover the features unlocked by Load Calc Guru's Pro plan, including full control over Manual J inputs, verified Manual S selection, and advanced reporting.
December 5, 2025
How to Document Your Blower Door Tests for Permits
Step-by-step guide for HVAC contractors to record, integrate, and report blower door test results for Manual J load calculations and AHJ approval.
November 25, 2025
Manual J for Permit Applications: A Contractor’s Guide to Passing AHJ Review
Learn how to prepare Manual J load calculations and reports that building departments and code officials actually approve.
November 18, 2025
How to Get the Inspector’s Approval (Without Rework)
What inspectors actually look for in Manual J and Manual S reports—and how to avoid failed inspections and last-minute revisions.
November 18, 2025
How to Get the Thumbs Up from the Inspector (Without Revisions)
What inspectors actually look for in Manual J and Manual S submittals—and how to avoid the most common reasons HVAC designs get rejected.
November 17, 2025
Free Manual J Calculators: What They Get Right (and Where They Fall Short)
A practical comparison of free Manual J calculators and why professional HVAC contractors still need dedicated load calculation software.
November 11, 2025
How to Use an Online Manual J Calculator for Residential HVAC Design
Step-by-step guide to using an online Manual J calculator to run residential heating and cooling load calculations, produce room-by-room BTU/hr loads, and generate HVAC load reports.
October 28, 2025
HVAC Load Calculation Software Buyer’s Guide for Small Contractors
What to look for when choosing HVAC load calculation software for Manual J, Manual S, and Manual D in a small residential HVAC business.
October 27, 2025
How to Run Your First Load Calculation (Without Overthinking It)
A practical walkthrough for running your first Manual J in Load Calc Guru—what to enter, what to ignore at first, and what actually matters.
October 26, 2025
Manual J, Manual S, and Manual D: How They Work Together for Residential HVAC Design
Understand how Manual J, Manual S, and Manual D connect to create a complete, code-compliant residential HVAC design workflow.
October 15, 2025
The basics of Manual J
A practical, no-nonsense guide to Manual J residential load calculations for HVAC contractors, designers, and homeowners.
October 7, 2025
How Load Calc Guru Works: The Methodology Behind the Numbers
A transparent look at how Load Calc Guru performs Manual J and Manual S calculations—and why the process matters more than the final number.
October 2, 2025
Manual J Calculator vs Rule-of-Thumb Sizing: Why Tons per Square Foot Fails
Compare a real Manual J calculator to rule-of-thumb HVAC sizing like 1 ton per 500 square feet, and see why proper load calculations matter for comfort, efficiency, and equipment life.
September 24, 2025
Room-by-Room Manual J: Why It Matters for Comfort, Zoning, and Duct Design
See why room-by-room Manual J load calculations are critical for residential HVAC comfort, zoning, duct design, and ductless head placement.
September 23, 2025
What Data You Actually Need for a Manual J Load Calculation
A practical checklist of the data you need to run a reliable Manual J load calculation, including plans, windows, insulation, blower door results, and design temperatures.
September 18, 2025
Common HVAC Permit Pitfalls and How to Avoid Them
A practical guide for HVAC contractors to avoid common mistakes in permit submissions and ensure AHJ approval using Load Calc Guru.