Are used to heat fluid to preheat the combustion improving fuel burners, to transport heat to recirculating the liquid radiator,
and in all places where you require a temperature increase.

They are constructed of a cylindrical body with mineral wool insulation within which housed the heating elements are subject to standard ASA flange 150 L with its respective box.

The elements are armored steel for oil and fuel oil, and copper or stainless steel for water, being in this case the internal cylindrical body dip galvanizing.