Abstract: A heat exchanger for boilers, in particular for condensing boilers. The heat exchanger having a set of heat exchanging plates inside which the water to be heated flows and outside which the combustion products coming from a burner pass. The heat exchanger has plates coupled to diaphragms for closing openings present on the plates; each plate having at least two levels of respective channels for the water flow to be heated. Hydraulic connections in series between the channels can be provided on the layer closest to a burner.

Abstract: An apparatus for adjusting and controlling the combustion in a fuel gas burner. The apparatus comprises the following mutually integrated components: a comburent gas/fuel gas mixing pipe provided with a Venturi mixer in correspondence of which a fuel gas supply duct opens; means for adjusting the flow rate of fuel gas; a fan, at least partially housed in said mixing pipe; a burner arranged downstream of said fan; a safety system based upon the detection of the flame present in said burner; and an electronic control unit of devices belonging to the apparatus. The apparatus is characterized in that it further comprises: a temperature probe arranged on the inner surface of the burner; a valve for adjusting the fuel gas flow rate in the duct; said valve belonging to said control means and being mechanically controlled by an actuator; and an electronic card, electronically connected to said probe, to said fan and to said actuator.

Abstract: An embodiment of a boiler comprises a fan, an air-gas premixing burner, a combustion chamber faced by a combustion head of the burner and a heat exchanger comprising a plurality of tubes in which the water of a heating system runs. The heat exchanger comprises cooling tubes arranged in contact either directly or with the interposition of an element formed by high heat conducting material, with a diffuser of the burner.