Heat exchanger

A heat exchanger comprising:

• a front wall;
• and
• a back wall forming a flue gas space together with the front wall such that a fluid flowing through a channel formed in the front wall and back wall can exchange heat with flue gas in the flue gas space, in use,
• an entirety of the back wall extending along a first plane, and the back wall being provided with a back fin,
• the front wall including
• a lower portion extending upwardly along the back wall, and
• an upper portion extending upwardly from an upper end of the lower portion and outwardly away from the back wall to form a combustion space of a flammable gas between the upper portion and the back wall, and the upper portion being provided with a front fin,
• the front fin and the back fin being arranged symmetrically with respect to a virtual line along which the flammable gas is to be injected into the combustion space, the virtual line intersecting with the first plane,
• a distance between the upper portion of the front wall and the back wall continuously increasing in the upward direction,
• the front wall and the back wall being asymmetric relative to a center line of the heat exchanger that extends substantially parallel to the first plane,
• the front wall being provided with front pins, the front pins extending backwardly from an inner surface of the front wall,
• some of the front pins being arranged at the upper portion of the front wall below the front fin,
• a remainder of the front pins being arranged at the lower portion of the front wall,
• the back wall being provided with back pins extending forwardly from an inner surface of the back wall, and
• the front pins arranged at the lower portion being connected to the back pins disposed at corresponding locations.