The four pages every contractor should review before installation: project assumptions, room loads, system summary, and infiltration.
A finished Manual J runs 8–20 pages. Most of it is the model output. There are four pages that actually matter on a jobsite, and once you know what to look for you can sanity-check any report in five minutes.
1. The project assumptions page
Check the design temperatures (winter and summer outdoor design temp, indoor setpoint), the climate zone, and the construction assumptions — wall R-value, window U-value and SHGC, infiltration rate. If any of those don't match the plan or the spec, the loads downstream are wrong.
2. The room-by-room load table
Every conditioned room should appear with sensible cooling, latent cooling, heating, and CFM. Rooms missing from the table are rooms that will be underserved. Rooms with surprisingly high loads usually point to a window or orientation issue worth raising with the designer.
3. The system summary
Total sensible + latent cooling and total heating, plus the design CFM. This is the number that feeds Manual S equipment selection. If the system total is wildly different from what was bid, stop and call the designer before ordering equipment.
4. The infiltration / ventilation page
Did the calc use a measured blower-door number, or the ACCA default? In a tight new-construction home, using the loose default can oversize the system by 20%+. In a leaky retrofit, using a tight assumption underestimates the latent load.
Five minutes on these four pages catches 90% of the problems before they're installed problems.
When to ask for a revision
- The design temps don't match your climate file
- A conditioned room is missing from the room-load table
- Window U-value or SHGC doesn't match the actual order
- Infiltration default looks wrong for the envelope
Revisions on our reports are included when the inputs change. Send us the updated plan or spec and we re-run.