Rhvac is a Windows desktop application for residential and small commercial HVAC design that performs ACCA-compliant Manual J load calculations, Manual D duct sizing with system loss and fan static pressure, and Manual S equipment selection with performance interpolation from any manufacturer. It computes room-by-room, zone, system, and whole-building loads; determines room CFM and building tonnage; and supports complex projects with many rooms, zones, and systems using drag-and-drop zoning. The software produces filled ACCA Form 310, HVAC design review, and Energy Star HVAC Design reports, and links with third-party compliance and rating tools such as REScheck, EnergyGauge, and REM/Rate, as well as Elite’s Ductsize and Energy Audit. Built-in weather data, HTM/U-value lookups from Manual J with user overrides, exterior shading inputs, hydronic radiant floor tubing length, and visualization aids (psychrometric chart, graphs, and color charts) help engineers design accurately and document results.

Key Features

Manual J load calculations ACCA-approved heating/cooling load calcs at room, zone, system, and building levels.

• Follows ACCA Manual J Eighth Edition; computes block and room-by-room loads.
• Built-in HTM/U-values with overrides; weather data for 1500+ cities, editable by user.

Manual D duct sizing and system losses Designs duct systems with performance data.

• Calculates duct sizes, system losses, and fan static pressure per Manual D.
• Enter full duct systems or individual ducts; previews rotation impacts on duct sizes (desktop).

Manual S equipment selection Selects equipment with performance interpolation.

• Generates ACCA Manual S Equipment Selection Report.
• Performs full Manual S interpolation using any manufacturer’s data.

Extensive project scale and zoning Handles large residential/light commercial models.

• Virtually unlimited rooms, 100 zones per system, and up to 100 systems.
• Drag-and-drop zoning; multiple sensible/latent loads per room.

Interoperability and compliance links Connects to energy and design tools.

• Links to REScheck, EnergyGauge, REM/Rate for compliance and ratings.
• Integrates with Elite Ductsize and Energy Audit; imports from Drawing Board floor plans (desktop).

Documentation and visualization Produces standard forms and visuals.

• Auto-fills ACCA Form 310, HVAC design review, and Energy Star HVAC Design reports.
• Psychrometric chart; color pie charts and bar graphs; custom proposals.

Benefits

Code-compliant, defensible designs Meets ACCA standards with traceable reports.

• Manual J/D/S compliance with ACCA approvals and auto-generated forms.
• Manufacturer-neutral performance interpolation supports accurate selection.

Faster, lower-error workflows Reduce rework with guided inputs and integrations.

• One-click help and drag-and-drop zoning accelerate setup.
• Links to REScheck/EnergyGauge/REM/Rate and Elite tools streamline compliance and sizing.

Scales from homes to small commercial Model complex projects without fragmentation.

• Large limits on rooms, zones, and systems support multifamily and light commercial.
• Rotation and shading tools capture real-world variability.