Forced-draft pre-mix burner device

A forced-draft pre-mix burner device comprising:

• a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet;
• a heat exchanger that warms the air prior to discharge via the warm air outlet;
• a gas burner that burns an air-gas mixture to thereby warm the heat exchanger;
• and
• a fan that mixes the air-gas mixture and forces the air-gas mixture into the gas burner, wherein the fan comprises
• a plurality of blades having sinusoidal-modulated blade spacing and configured to rotate about an axis of rotation, wherein the plurality of blades radially extends relative to the axis of rotation,
• an end cap having an end wall that faces the plurality of blades,
• an air-gas mixture inlet formed through the end wall radially between the radial center and the radial outer end and through which the air-gas mixture is conveyed to the plurality of blades,
• an air-gas mixture outlet formed through the end wall radially between the radial center and the radial outer end and through which the air-gas mixture is conveyed to the gas burner, and
• a channel formed in the end wall and axially facing the plurality of blades, the channel having a length extending around the radial center from the air-gas mixture inlet to the air-gas mixture outlet, wherein the channel gradually becomes shallower along an entirety of the length from the air-gas mixture inlet to the air-gas mixture outlet, so as to gradually introduce the air-gas mixture axially into the plurality of blades.

A forced-draft pre-mix burner device comprising:

• a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet;
• a heat exchanger that warms the air prior to discharge via the warm air outlet;
• a gas burner that burns an air-gas mixture to thereby warm the heat exchanger;
• and
• a fan that mixes the air-gas mixture and forces the air-gas mixture into the gas burner, wherein the fan comprises
• a plurality of blades having sinusoidal-modulated blade spacing, wherein the plurality of blades rotates about an axis of rotation extending in an axial direction, and further wherein the plurality of blades extends radially relative to the axial direction,
• an end cap having an end wall that faces the plurality of blades, and
• an air-gas mixture inlet through which the air-gas mixture is conveyed to the plurality of blades and an air-gas mixture outlet through which the air-gas mixture is conveyed to the gas burner, wherein the air-gas mixture inlet is connected to the air-gas mixture outlet via a channel formed in the end wall, the channel facing the plurality of blades in the axial direction, and further wherein between the air-gas mixture inlet and the air-gas mixture outlet the channel gradually becomes shallower so as to gradually introduce the air-gas mixture into the plurality of blades in the axial direction as the air-gas mixture is conveyed along the channel.