RX 18÷3 S/E ULN

The gas burners in the Riello RX S/E ULN range have been designed and developed by Riello with premix combustion technology. They represent the best solutions for low polluting emissions and develop high modulation ratios.

In the RX S/PV ULN burners, the perfect mixture of air and gas is created inside the pipe coupling, upstream of the combustion head. The air/gas mixture is distributed in the combustion head or “support”. It consists of a metal cylinder with dedicated surface holes for mixture outlet.

Thanks to this premix technology, combustion occurs close to the metal mesh and the support, resulting in a very compact flame. It also reduces the probability of contact between the flame and the walls of the combustion chamber. The result is that this head type can be combined with a variety of combustion chambers and is highly flexible when matching equipment.

RX S/E ULN burners offer electronic cam modulating operation (model REC 27.1) for high-precision fuel and combustion air adjustment, thanks to the use of dedicated servo motors.

Maximum air-gas mixture efficiency and output control, guaranteed by the RXS/ ULN burners, combined with the premix combustion head, guarantees low polluting emissions, high combustion efficiency, and high turn-down ratios (on average 7:1). Furthermore, the burner is fired by pilot flame to guarantee regular start up even under conditions with excess air.

The combustion heads of all RX S/E ULN models are equipped with the RRD (Resonance Reduction Device) that minimizes all possible resonance phenomena. The output hole shape has been specifically designed to optimize the air/gas mixture speed to avoid any potential hazard due to flame return across the entire modulating range.


During the installation of a Riello premix burner in the RX S/E ULN range, a number of parameters must be taken into consideration. These include the boiler type the burner will be installed on, the boiler door thickness, the type of gas used, the frequence of maintenance and service interventions, the stack pressure, etc.

Any order that includes the Riello RX S/E ULN range of burners is the product an in-depth preliminary study of the future of the installation. It is accompanied by a detailed quotation prepared by Riello sales offices and/or technicians.

  • Premix gas burners
  • Ultra Low NOx emissions (NOx ≤ 3 mg/Nm3)
  • Compact flame (Riello patented combustion head with metal fiber mesh)
  • Electronic cam modulation
  • Three models from 3 to 321 kW
  • Average turn-down ratio 1:7
  • Firing with pilot flame
  • Natural gas and LPG operation
RX 18÷3 S/E ULN




RX 1800 S/E ULN 3/400/50-60 230/50-60
Type Language
BIM model English Download
RX 2500 S/E ULN 3/400/50-60 230/50-60
Type Language
BIM model English Download
RX 3000 S/E ULN 3/400/50-60 230/50-60
Type Language
BIM model English Download