Choosing the Right Fit For Your Facility
At Icon Boiler, we know that selecting the right boiler technology is a critical decision for any commercial facility. Firetube and watertube boilers are both proven options, but each is designed to support different operational needs. Understanding how they compare can help you make a more informed decision for your building.
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Firetube |
 Watertube |
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| Capacity Requirements | 1200 BoHP – 41,400 lb/hr – 40 MM Btu output Maximum: 2,500 HP (85,000 lb/hr) |
1,160 BoHP – 40,000 lb/hr – 40 MM Btu output Maximum: 300,000 lb/hr (8,700 BoHP) |
| Pressure Needs | Operating Pressure – 160 psig Design Pressure – 200 psig (Standard 150 psig, Maximum 300 psig) |
Operating Pressure – 180 psig Design Pressure – 250 psig (Standard 250 psig, Maximum 1,250) |
| Steam Requirements | Works for saturated steam only (heating water only) | For superheated (radiant or convective), watertube is required. Also works for saturated steam. |
| Steam Quality | 99.5% | 99.5% – 99.9% |
| Efficiency | 82–83% without economizer 83.5–86% with economizer |
78–79% without economizer 82–83% with economizer |
| Site Concerns – Space Limitations | Smaller models available to fit through doors. Generally longer than watertube. | Smaller footprint but generally taller than firetube. Can be customized for shorter length. |
| Weight Limits | 81,300 lb dry weight 180,000 lb flooded weight |
55,214 lb dry weight 77,025 lb flooded weight |
| Load Swing | Handles wide swings in process steam more easily due to larger volume of water. Longer initial startup. | Heats from cold to operating pressure more quickly (less water to heat). Typically has a shorter turndown. |
| Maintenance | Easier to maintain than watertube. Maintenance completed from outside of unit. | Tube bending offered for quicker replacements. More refractory areas of repair. |
| Fuel/NOx | Burner neutral. Can use a number of fuels (natural gas, No. 2 fuel oil, hydrogen, combined gas and oil, propane digester, solid fuel). < 9 ppm NOx < 30% FGR < 15% excess air |
Burner neutral. Can use a number of fuels (natural gas, No. 2 fuel oil, hydrogen, combined gas and oil, propane digester, solid fuel). < 9 ppm NOx < 30% FGR < 15% excess air |
| Financial – Lead Time | On average, costs 40–45% less than watertube (boiler only). 10–18 week lead time |
On average, costs 40–45% more than firetube. 26–32 week lead time |
| Longevity (depending on maintenance) | 18–20 years | 30–40 years |
Both boiler types can perform reliably when applied correctly. The right choice depends on your facility’s capacity needs, space constraints, maintenance resources, and long‑term operational goals.