Enter Boiler Sizing Inputs
Example Data Table
| Project | Area (m²) | Load (W/m²) | DHW (kW) | Process (kW) | Efficiency (%) | Suggested Output (kW) |
|---|---|---|---|---|---|---|
| Office Block A | 1500 | 85 | 35 | 20 | 88 | 201.66 |
| School Wing B | 2200 | 78 | 25 | 0 | 90 | 211.91 |
| Hotel Tower C | 3400 | 95 | 90 | 30 | 86 | 462.18 |
Formula Used
1. Envelope heating load
Envelope Load (kW) = Area × Design Load × Climate Factor × Occupancy Factor × Diversity Factor ÷ 1000
2. Flow based heating load
Flow Load (kW) = Flow (L/min) × 4.186 × Temperature Difference ÷ 60
3. Base heating demand
Base Load = Greater of Envelope Load or Flow Load
4. Total connected load
Subtotal Load = Base Load + DHW Load + Process Load + Future Load
5. Pickup and distribution adjustment
Adjusted Load = Subtotal Load × Pickup Factor × (1 + Distribution Loss%)
6. Recommended boiler output
Boiler Output = Adjusted Load × (1 + Reserve Margin%)
7. Required boiler input
Boiler Input = Boiler Output ÷ Efficiency
8. Steam conversion
Steam kg/hr = Boiler Output × 3600 ÷ Steam Latent Heat
How to Use This Calculator
- Enter the project name and choose boiler mode.
- Add the heated floor area and design heat load.
- Adjust climate, occupancy, diversity, and pickup factors.
- Enter distribution loss, reserve margin, and boiler efficiency.
- Add domestic hot water, process, and future expansion loads.
- For hot water systems, enter supply and return temperatures.
- Enter flow if you want a flow based load check.
- Set latent heat and operating hours for steam review.
- Select boiler count for modular plant sizing.
- Press calculate to show results above the form.
Frequently Asked Questions
1. What does this boiler sizing calculator estimate?
It estimates recommended boiler output, fuel input, capacity per unit, steam equivalent, and related design checks using area, load, losses, margins, and efficiency.
2. Why are pickup and reserve margin included?
Pickup accounts for warmup demand and startup effects. Reserve margin supports resilience, future uncertainty, and practical plant selection without undersizing the equipment.
3. Should I use area load or flow load?
This tool compares both and uses the greater value as the base load. That helps prevent underestimation when the system flow implies a larger demand.
4. Can this calculator size steam boilers?
Yes. It converts calculated output into estimated steam production using latent heat. That gives a quick kg/hr and lb/hr reference.
5. What efficiency value should I enter?
Use the expected seasonal or design efficiency from manufacturer data or project standards. Conservative efficiency values usually produce safer input estimates.
6. Does this replace a full mechanical design?
No. It is a planning and checking tool. Final sizing should consider codes, altitude, controls, redundancy philosophy, and detailed heat loss calculations.
7. Why divide capacity across multiple boilers?
Multiple boilers can improve turndown, redundancy, maintenance flexibility, and seasonal efficiency. The calculator shows approximate capacity per boiler for planning.
8. What units are provided in the results?
Results include kW, BTU/hr, MBH, tons, boiler horsepower, steam kg/hr, steam lb/hr, and daily energy for broader engineering review.