CaptiveAire Toolbox

Toolbox is an HVAC engineering app from CaptiveAire. It is built for design engineers, mechanical contractors, sales engineers, and service techs who size systems every day, and it puts the calculators and reference data they reach for most often in one place on the device they already carry.

What's inside:

Cooling: sensible and latent loads, evaporative cooling, condensation, RTU comparison, refrigeration tonnage.

Heating: BTU sizing, heat pump performance, reheat coils, gas pipe sizing.

Ventilation: outdoor air requirements, makeup air, fan energy index (FEI), motor frequency, duct velocity and CFM.

Electrical: MCA, MOCP, wire sizing, amperage and voltage drop.

Structural: pitched roof loads, pressure drop across ductwork.

Climate tools:

Psychrometric chart with full process plotting (mixing, heating, cooling, humidification, evaporative, sensible heating). Tap any state point to see properties, drag to adjust, layer multiple processes.

Weather station lookup with ASHRAE design conditions for any US ZIP code or city. Heating, cooling, dehumidification, and extreme design days, all from the official station data.

Designed for the field:

Works on phone or tablet.
No account, no signup, no paywall.
Dark mode for late nights and bright displays.
Results update instantly as you change inputs. No submit buttons, no waiting.

About CaptiveAire:
CaptiveAire Systems is a leading manufacturer of commercial kitchen ventilation and tempered makeup air equipment. Toolbox is offered free as a service to the HVAC engineering community.

Questions, feedback, or bug reports: support@captiveaire.com

Recent changes:
Bug fixes and improvements