Most failed HVAC inspections aren’t caused by bad math.
They’re caused by missing proof.
Inspectors are not trying to redesign your system. They are checking whether your design follows a defensible process and whether the documentation supports the decisions you made. If your reports don’t clearly show that process, expect questions—or rejection.
Here’s what inspectors actually care about, and how to avoid rework.
What Inspectors Are Verifying (Not Guessing)
At a minimum, inspectors want to confirm three things:
- A Manual J load calculation exists
- Design conditions are clearly stated
- Selected equipment is appropriate for those conditions
If any of those are unclear, they don’t assume you did it correctly—they assume you didn’t.
Manual J: Clarity Beats Complexity
Inspectors don’t audit every wall assembly. They scan for red flags.
They want to see:
- Room-by-room or zone-level loads
- Explicit indoor and outdoor design temperatures
- Transparent assumptions for infiltration and construction
Problems arise when:
- Design conditions are buried or omitted
- Loads appear suspiciously round
- Inputs look copy-pasted across projects
Load Calc Guru surfaces design conditions and assumptions directly in the report so inspectors don’t have to hunt for them.
The Biggest Red Flag: “3-Ton System” With No Manual S
This is where most projects fail modern inspections.
Saying:
“The load is 34,000 BTUs, so we installed a 3-ton unit”
is no longer sufficient.
Inspectors increasingly expect:
- Equipment model numbers
- Capacity verification at design conditions
- Sensible and latent capacity confirmation (for cooling)
- Low-ambient performance (for heat pumps)
That’s Manual S. Without it, you’re asking the inspector to trust marketing brochures instead of performance data.
They won’t.
Design Conditions Must Match Reality
One of the fastest ways to lose credibility is mismatched design data.
Common mistakes:
- Using default outdoor temperatures that don’t match the jurisdiction
- Changing indoor setpoints without documenting why
- Ignoring humidity assumptions in cooling climates
Inspectors don’t object to overrides. They object to undocumented overrides.
When values are customized, they should be clearly labeled and justified in the report.
Duct Losses Are No Longer Optional
Even if ducts are “inside conditioned space,” inspectors want to see that you accounted for them.
Ignoring duct losses entirely:
- Inflates delivered capacity
- Undermines Manual S verification
- Signals an incomplete design
Load Calc Guru allows duct losses to be modeled explicitly or conservatively assumed, and reports them clearly—no hand-waving required.
Read Your Report Like an Inspector Would
Before submitting, ask yourself:
- Can someone unfamiliar with this project understand the logic?
- Are assumptions obvious?
- Is there a clear trail from load → equipment → capacity verification?
If the answer is no, expect a correction request.
Passing Inspection Is About Defensibility
Inspectors don’t need perfection.
They need confidence that:
- You followed ACCA methodology
- You didn’t guess
- You can explain your decisions
Clear Manual J inputs and verified Manual S outputs do exactly that.
When your reports tell the full story, inspections stop being stressful—and start being routine.