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FTB Heavy Duty Steel Boiler


The range of AIRATHERM FTB Hot Water Boilers are constructed to conform to AS1210 with only certified materials used in the vessel construction. The boiler safety and control interlock systems feature the highest quality components ensuring a safe operating boiler.

The AIRATHERM Heavy Duty FTB series boilers are all completely assembled and factory tested before delivery minimizing costly commissioning down time.


  • Low Maintenance

  • Easy Access

  • Durable

  • 82% plus efficiency

  • Modern 3-Pass Wetback design 

  • 500 kPa standard operating pressure

  • Australian Made



  • Gas - ON/OFF, HI/LO or Modulating

  • Oil - HI/LO - ON/OFF

  • Weatherproof option

  • Low Maintenance 

  • Special Operating Pressures up to 1100 kPa

The AIRA FTB has a generous heating surface area proportioned in the boiler for maximum operating efficiency and boiler life. The boilers cylindrical combustion chamber is completely wetted due to the boilers reverse flame design. The large diameter furnace makes use of the most efficient section for heat transfer, the radiant zone. Resulting in high efficiency heat transfer and lower convection tube entry temperatures maximizing tube and tube plate life. Due to the reverse flame design, the first two passes take place in the furnace. The advantage of this is that the second gas pass causes a blanket of hot gasses protecting the furnace from flame impingement and giving more even heat transfer and extendes furnace life. This design also minimises the quantity of unburned gases passing to the fire tube pass, resulting greater operating efficiency. The fire tube pass consists of a crown of straight tubes totally encircling the combustion chamber. The tube velocity is such that complete turbulence is achieved in the vicinity of the tube entrance to ensure maximum even heat transfer. As well as this, a turbulator is installed into each tube to maximize the limit exchange heat transfer with an even gas scrubbing effect on the inside tube surface. This process ensures that an even temperature distribution on the tube circumference providing excellent gas distribution mixing ratios giving an even heat transfer to the water.

Each turbulator is removable to enable boiler cleaning and maintenance.

The boilers wet back design also minimizes the need for refractory lining and therefore minimizing possible expensive repairs. External heat loss is minimized due to the boiler shell being wrapped in heavy-duty insulation material and lagged in an attractive enamel painted casing.

The water enters the boiler via the front flanged connection, passing over a system of internal baffles to ensure an even flow across the boilers heating surface. As well as ensuring the maximum possible heat transfer, this also keeps any parts in contact with the combustion gasses at a safe working temperature. The water then exits boiler via the rear-flanged connection.

The AIRA Heavy Duty FTB boilers hinged front door can be either right or left-hand opening due to the hinge design. Once the front door is open the furnace and smoke tubes are completely accessible for cleaning and any maintenance work which may need to be carried out.

The only refractory used in the boiler construction is in the front door and as only the finest quality materials are used, maximum insulation properties and long life (under normal operating conditions) can be assured.


  • Designed in accordance with AS1210

  • Manufactured to AS4458 Pressure equipment manufacture

  • Welders Qualified to AS3992. Weld procedures formulated by a qualified welding engineer.

  • Non destructive testing to AS4037

  • Boiler shell, furnace and tube plates = AS1548/7/460 boilerplate & AS3678 GR250.

  • All boiler tubes used = BS 3059 ERW 320 & astm a 106 Gr. “B”

  • Inlet, Outlet, connections and vent pipe = ASTM A 106 Gr. “B”

  • Flanges = AS2129 table “E”

  • Boiler insulation = 50mm Tontine fibre

  • External Panels = 1mm galvanized sheet

  • Refractory = pearlite and cement fondue

  • Pressure and temperature gauges

  • On/Off thermostat

  • HI/LO thermostat 

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