# Flue Gas Combustion Calc — Excess Air & Efficiency Tool

> Excess Air & Efficiency Tool (iPhone/iPad app by Shanghai Sheyuan Network Technology Co., Ltd..)

- Source: https://appshunter.io/ios/app/flue-gas-combustion-calc/id6761745722 (this page in markdown: same URL + `.md`)
- Developer: [Shanghai Sheyuan Network Technology Co., Ltd.](https://appshunter.io/developer/1560626858)
- Category: Utilities
- Price: $4.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: English
- Released: 2026-04-07
- Data updated: 2026-07-08
- User reviews in markdown: https://appshunter.io/ios/app/flue-gas-combustion-calc/id6761745722/reviews.md

## What is Flue Gas Combustion Calc?

Tuning a boiler or furnace and need to verify combustion efficiency on the spot? Enter fuel type, flue oxygen percentage, flue temperature, ambient temperature, and CO level in ppm. Get instant readings for excess air percentage, combustion efficiency, stack loss, and CO safety status with color-coded alerts.

Supports Natural Gas, Propane, Oil, and Coal fuel types.

WHAT IT CALCULATES:
- Excess air percentage from flue O2 reading
- Net stack temperature (flue minus ambient)
- Stack loss percentage
- Combustion efficiency percentage
- CO safety status: Good (green), Marginal (yellow), Dangerous (red)

KEY FEATURES:
- Four fuel types built in
- Color-coded CO safety alert
- Instant results as you adjust inputs
- Clean, field-friendly interface
- Works completely offline
- No account or login required

Built for boiler technicians, HVAC service professionals, and combustion engineers who need quick efficiency checks during tuning and commissioning.


## Version history (last 3 releases)

### 1.0.2 — 2026-06-27

Added a More Pro Tools section to discover related field calculators.

### 1.0.1 — 2026-04-12

Bug fixes and performance improvements.

### 1.0 — 2026-04-07

No release notes.

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All apps by Shanghai Sheyuan Network Technology Co., Ltd.: https://appshunter.io/developer/1560626858

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-08.*