- Gas fired water boiler with cast aluminum heat exchanger

- Venturi mixing body mixes air and gas providing higher efficiency

- Designed to operate in low temperature condensing applications

- Outdoor reset and domestic hot water priority standard

- Negative regulated gas valve precisely delivers gas to the boiler

- U-Control gives you the power for easy set-up and maintenance

- Modulates with 5 to 1 turn-down ratio

- Variable speed motor matches combustion output to heating needs

- High grade stainless steel burner features quiet operation, high efficiency, and cleaner combustion for low NOx applications

- *Ultra 310 93.3% AFUE rating is a gross output and combustion efficiency.