SEER2
HSPF2
Equipment is evaluated using OEM expanded performance data at design conditions, not nominal tonnage.
Step 1: Manual J Design Loads
Confirm the Manual J design conditions. These values drive equipment selection and airflow requirements.
No Manual J data?
Calculate BTU & Tonnage FirstCooling design load
Use the final Manual J design payload: total, sensible, latent, indoor design conditions, outdoor design dry bulb, and target airflow. Manual S should work from a normalized reference payload rather than ad hoc field labels.
Heating design load
Heating-side data must include the winter design heat loss, indoor design setpoint, outdoor winter dry bulb, and airflow target if the blower target differs from cooling mode.
▾
Reference handshake
Manual S works from a normalized reference payload, not raw Manual J field labels.
Step 2: Equipment Universe
Filter the equipment universe by brand, type, and nominal size. Storage uses flat point arrays; runtime builds indexed lookup maps for interpolation.
▾
▾
▾
▾
Step 3: Interpolated Performance Audit
The solver screens the equipment universe against total, sensible, latent, heating, and oversize limits, then prepares the selected blower/static bridge for Manual D.
✓
Step 3 resolution
Manual S Verification Passed
Calculated total
Calculated sensible
Calculated latent
Sizing deviation
Total ✓
Sensible ✓
Latent ✓
Oversize ✓
Step 3 resolution
No Passing Match Found
Closest candidate
Primary limiter
Design point
Manual J total
Manual J sensible
Manual J latent
Cooling cap
Interpolated total · sensible · latent
Oversize
SEER2
EER2
HSPF2
Limiter
Step 4: Results & Manual D Bridge
Selected equipment summary plus blower/static pressure data for the duct friction-rate workflow.
Final result locked
Live preview stays visible. Final selection unlocks after acknowledgement.
Use the desktop right-side snapshot to review the current load, net capacity, deviation, and governing limiter while you work. Final selection details, print, and Manual D handoff stay gated until the professional acknowledgement is checked in Step 3.
Selected equipment
This selection currently clears total, sensible, latent, and oversize checks inside the demo universe.
Selection schedule
Calculated total
Calculated sensible
Calculated latent
Heating output
SEER2
HSPF2
Manual D bridge
Manual D consumes the selected design airflow, blower profile, ESP point, and device pressure drops. Those values are exported here for the friction-rate solver: ASP = ESP − DPL, then FR = (ASP × 100) / TEL.
Design CFM
Blower profile
TESP point
Delivered CFM
Coil ΔP
Filter ΔP
No passing match yet
Run the selection, or refine the design load and equipment filters. When no candidate passes, the no-match engine should return actionable adjustment guidance.
TradeHub HVAC Workflow
Manual S connects load calculations to duct design
Manual J defines the design load. Manual S screens the equipment at the actual design point. Manual D carries the selected airflow, blower, and pressure assumptions into the duct workflow. This page is the selection layer in that connected system.
Workflow position
Residential → Manual J → Manual S → Manual D
Dependency
Start with Manual J
Manual S should read a finished load profile first so total, sensible, latent, and winter design targets are grounded before equipment screening begins.
← Back to Manual JCurrent page
Manual S Equipment Selection
This workflow compares OEM-expanded performance to the Manual J design point, then prepares the selected blower and pressure assumptions for the downstream airside workflow.
Selection Layer
OEM Screened
Manual D Ready
Next step
Carry the result into Manual D
Once equipment clears the screen, use the selected airflow, TESP point, and device pressure drops as the starting reference for friction-rate and pressure-budget work.
Continue to Manual D →Technical Review
Manual S Equipment Selection Reference Context
This workflow follows ACCA Manual S® equipment selection principles using Manual J® design loads and manufacturer expanded performance data. It supports structured screening of total, sensible, latent, and heating capacity against design conditions. Final equipment selection, AHRI matching, manufacturer data, and local code requirements should be verified prior to installation or permitting.
Code Audit Date: April 2026
Field Guide · Manual S Content Layer
How to Use This Manual S Workflow
This section is built for contractors and field users who need to understand what the engine screened, why a system passed or failed, and what should happen before the result is carried into Manual D or equipment ordering.
Content strategy
Most important section opens first. Everything else stays collapsed until needed.
What the engine reads
The workflow starts with a normalized Manual J payload, then compares each equipment candidate using OEM expanded performance data instead of nominal tonnage alone. Cooling is screened at design outdoor dry bulb, entering wet bulb, and target airflow. Heating is screened at the selected winter design dry bulb and airflow target.
What the engine decides
The solver verifies total capacity, sensible capacity, latent behavior, heating output, and oversize limits. It then carries the selected blower profile, delivered airflow point, and pressure-drop assumptions into the Manual D bridge so the airside design stays connected to the equipment choice.
Live solver linkage
Current candidate
Primary limiter
Cooling design point
Heating design point
Interpolation / audit
1. Manual J intake
Normalized bridge object, not loose form labels.
2. OEM interpolation
Expanded point grids at actual design conditions.
3. Capacity split
Total, sensible, and latent are checked separately.
4. Heating screen
Winter design output is compared against the heat loss target.
5. Manual D bridge
Selected airflow and pressure assumptions are exported forward.
Cooling capacity validation
The engine verifies that interpolated total cooling capacity meets the Manual J total load and that sensible capacity is strong enough to handle the sensible portion of the load. Latent is then reviewed as its own part of the split.
Heating capacity validation
Heating output is screened at winter design temperature and target airflow so the selected system is not accepted on rated nameplate claims alone.
Oversize limits
Passing a job is not only about being above the load. The engine also rejects candidates that exceed the allowed cooling oversize band for the selected mode.
Airflow and blower readiness
The chosen result carries blower profile, delivered CFM, TESP point, and device pressure-drop assumptions so the equipment result can still be defended once the airside workflow begins.
Current solver readout
Candidate
Limiter
Total capacity failure
A candidate fails when interpolated total cooling output stays below the Manual J total load at the actual design point.
Sensible capacity failure
This is often the deciding limiter in humid climates or higher sensible homes. A system can show acceptable total capacity and still fail because sensible output is not high enough.
Latent mismatch
Latent output is reviewed separately because a system can over-carry moisture removal, under-carry it, or simply split capacity in a way that does not match the home profile well.
Oversize rejection
A larger unit is not automatically the right answer. Once a candidate exceeds the acceptable oversize band, it should be treated as a problem to investigate, not a win.
Airflow and bridge constraints
Even a capacity pass still needs a believable blower path. The workflow carries the selected profile and pressure assumptions forward because airflow problems can invalidate an otherwise attractive equipment match.
1. Confirm loads
Start by verifying that the Manual J payload is final and not a rough draft.
2. Compare candidates
Look at the nearest passing option when one exists, or the closest failing candidate when no system clears the screen, instead of jumping to nominal tonnage.
3. Verify blower path
Check delivered airflow, TESP assumptions, and device pressure drops before locking the equipment.
4. Carry into Manual D
Use the bridge values as the starting point for friction-rate and pressure-budget work.
- OEM submittals, installation instructions, and match-specific notes still govern the final equipment decision.
- The result does not replace AHRI verification, final commissioning, or field airflow testing.
- Local code requirements and AHJ interpretations can still change the final path.
- The tool is a decision-support layer for qualified HVAC users, not a substitute for professional judgment.
Why did a 2.5 ton system fail?
Because nominal size does not guarantee design-point capacity. The result can fail on total, sensible, latent split, heating output, or oversize rules once actual conditions are applied.
Why does sensible capacity matter so much?
Because many homes are limited by sensible load, not just total load. A system can look close on total and still fail the job if sensible output comes in short.
Why does airflow change the result?
Airflow shifts the capacity split and changes the point being evaluated. That is why Manual S should use OEM expanded data instead of fixed tonnage assumptions.
Why does the result feed Manual D?
Because airflow target, blower profile, and pressure-drop assumptions all affect duct design. The equipment choice and the airside design should stay connected.