SetsubiWorks HVAC Sizing Calc

No more squinting at a calculator on site.

SetsubiWorks puts nine calculations that HVAC and plumbing engineers reach for every day - design, site supervision, cost estimation - into a single app on your phone. The calculation logic is a native iOS port of an internal Django tool that has been used on real projects.

WHAT IT DOES
- Unit Conversion - primary energy conversion for electricity, city gas and COP
- Air State Calculation - moist air properties from dry-bulb temperature and any humidity index (relative humidity, wet-bulb, dew point, absolute humidity)
- AHU Psychrometric Chart - cooling and heating processes, capacity and water flow, with a natively drawn psychrometric chart
- Air Conditioning Equipment Calculations - supply airflow, sensible heat load, coil water flow and required humidification
- Duct Size Selection - spiral and rectangular duct sizes from airflow
- Louver / Grille Size Selection - louver and grille sizes from airflow
- Water Supply Pipe Selection - nominal pipe size from flow rate
- Drainage Pipe Size Selection - drainage pipe sizing using the Manning and Kutter formulas
- Equipment Combined Noise Calculation - combines the SPL of multiple units with distance attenuation

BUILT-IN CALCULATOR ON IPAD
On iPad, Duct Size Selection and Louver / Grille Size Selection come with a calculator panel. Enter several airflows as a formula, such as 1200+800+650x2, and the app adds them up and goes straight to sizing. With the calculator on the left and the results on the right, the large screen makes design reviews and drawing checks faster.

WHO IT IS FOR
A quick check on site, a rough figure during a meeting, some groundwork before an estimate - the moments where opening a laptop is overkill but a pocket calculator is tedious. Useful for design engineers, site supervisors and estimators, and for students checking their own answers while studying for professional qualifications.

PRICING
All features are free for 14 days after installation. After that, a single one-time purchase keeps every feature unlocked. There is no subscription and no monthly fee.

DETAILS
- Requires iOS 16.0 or later
- No network communication, no data collection. Every calculation runs on your device
- Available in Japanese, English, Simplified Chinese and Vietnamese
- Results are reference values. Always have a qualified engineer verify them before applying them to actual design or construction

Feedback and bug reports are welcome from the in-app settings screen or via the support link below.