Diathermic oil boiler with three flue passes


Diathermic oil boilers featuring a helical tube bundle with one or more turns and three effective flue passes.

Designed to operate in combination with jet burners on liquid (including high density) or gas fuel.

Range consisting of 15 models with useful heat outputs from 117 to 5814 kW and steam production, in combination with EVA series evaporator, from 166 to 8300 kg/h.

  • Technical Data

    Standard design pressure 10 bars

    Operating temperature up to 300°C for mineral oils and 350°C for synthetic oils, with a temperature difference between oil inlet and outlet of around 40°C.

    Upon request boilers can be developed with different temperature values and differences from those indicated above.

    Construction with two concentric rings inside in a cylindrical sheet metal body that’s tight to the flue gas. The first “ring” represents the furnace that the flame extends along; the second “ring” is the start of a three flue pass circuit that optimises use of the entire heat exchange surface, making it advantageous to use low NOx burners.

    Tube bundle made from carbon steel without welding.

    Access to the furnace is available through a burner door hinged to the boiler that can be opened from the right or the left; the door is lined on the inside with a suitably thick layer of refractory concrete and features a flame inspection opening and burner anchor plate.

    The rear smokebox is bolted to the boiler, and lined on the inside with insulating concrete, and is fitted with cleanout door and attachment for the flue connection.

    These modern-concept and high-efficiency generators have been designed and developed in compliance with European directive 2014/68/UE (PED) and the most recent national and European standards on pressurised recipients.

    The boiler body is lined by a suitable layer of high density rock wool, protected by stainless steel plate (AISI 430); this reduces heat loss and improves overall efficiency.

    Vertical version on request.



    • CE mark in accordance with the following directives
    • Pressure Equipment (2014/68/UE)
    • Low Voltage (2014/35/UE)
    • Electromagnetic Compatibility (2014/30/UE)



    Air preheater: a flue gas/air heat exchanger to be installed in the flue gas circuit between the boiler and the chimney. This increases thermal efficiency by around 4%. This solution requires an industrial burner with separate fan to be installed upstream of the preheater.

    Burner: brand and type chosen based on customer specifications.

    Perforated burner plate based on customer specifications.

    Oil circulating pump assembly with 1 or 2 pumps, complete with valves, filters, compensators and pressure gauge.

    Instrument panel complete with operating and safety temperature controllers.

    System electrical control panel (boiler, circulating pump, expansion vessel etc.).

    Oil filling pump.

    Oil degasser: degasser tank for optimum air removal when filling the heater and during operation.

    Oil collection tank.

    Open expansion vessel.

    Pressurised expansion vessel.

    B.E.C.S. (Boiler Electronic Configurable System): the B.E.C.S. control system consists of a PLC fitted with high performance Touch Panel colour operator interface. The interface can be used to manage operation of the Boiler-Burner-Central Heating System.

    Pneumatic temperature control with on-off valves.


    If an evaporator is connected the following are available on request:

    Hydraulic connection between ELICOIL NO and Evaporator.

  • Depliant

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