About this app
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.
Latest release
What’s New
Added a More Pro Tools section to discover related field calculators.
Audience growth
Ratings growth
Baseline captured. Growth appears after the crawler observes a changed rating count.
Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.
Price tracking
Price intelligence
First snapshot captured. The trend line starts after the next crawler price observation.
- First observed Oct 2, 2026 · 7:51 PM $4.99
Screenshots
