FCX Boiler Features

FCX Boiler 92-97% AFUE Rating

Thousands of installations worldwide have proven the FCX boiler to be most reliable and efficient.


  • A steel, primary non-condensing heat exchanger coupled to a condensing, stainless secondary heat exchanger
  • A built-in three-way mixing valve permits all-season comfort at maximum efficiency
  • Dual-temperature circuit capability, which makes combining low and high-temperature applications in the same structure quick and easy
  • Ideal for year-round DHW service and is so silent, clean and nicely finished that it can be installed almost anywhere within most buildings
  • Approved as a sealed-combustion device taking its combustion air from outside via a concentric vent or it can use room air for combustion
  • Riello RDB Burners

RIELLO Light Oil Burners Instruction Manual

FCX Plumbing

FCX Plumbing Energy Star

A Burner
B Sight glass
C Primary, Non-Condensing
Heat Exchanger
D Secondary, Non-Condensing
Heat Exchanger
E Mixing Valve and Circulating Pump
F System Drain
G Combustion-AirTube
H Return from Optional High-Temp Circuit
I Return from Low-Temp Circuit
J High-Temp Supply Circuit
K Low-Temp Supply Circuit
L Combustion-Air In
M Flue-Gas Out
N Condensation Outlet