Navien NFB-C commercial condensing fire tube boilers have all key components designed and manufactured in-house, and offer a 97.5% thermal efficiency, 15:1 turndown ratio, intuitive 7” color touch screen with advanced controls and easy intuitive navigation for setup, troubleshooting and operation, extremely low NOx levels, BMS communications, and 3” venting up to 60’ or 4” up to 150’ with PVC/CPVC/PP/SS approved materials, the company says.