Main characteristics: 1. Vertical fire tube prevents scale deposition. 2. Flanging and butt-welding ensure maximum fatigue tolerance. 3. High-efficiency heat transfer performance, reduced heat loss. 4. Programmable combustion control. 5. Three pressure controllers installed to avoid overpressure. 6. Auto water feeding, low alarm float switch. 7. Easy maintenance. 8. Compact design, easy to install and operate.