A through-flow type narrow-clearance integral condensation hot-water boiler comprises a shell. An annular water outlet header is arranged on the upper portion of the shell, an annular water feeding header is arranged on the lower portion of the shell, a deep condensation heat exchange tube bundle and a V-shaped condensation collecting device with a condensate neutralizing treatment device are arranged below the annular water feeding header, an all-premixing
metal fiber combustor is arranged on a top plate of a boiler, a
metal fiber head of the all-premixing
metal fiber combustor penetrates into a
radiation heat exchange space so as to realize the characteristic of
high radiation heat exchange capacity of the
metal fiber head, the annular water outlet header is communicated with the annular water feeding header via inner and outer circles of annular
water cooling walls consisting of a plurality of vertical water tubes, a clearance with the size of 1-2mm is reserved between each two adjacent vertical water tubes and is used as a
smoke circulation channel,
smoke realizes
convection heat exchange and condensation heat exchange when flowing among the vertical water tubes, heat is transmitted to working medium water in the vertical water tubes, the deep condensation heat exchange tube bundle deeply cools the
smoke, and efficiency of the boiler is improved. In addition, the through-flow type narrow-clearance integral condensation hot-water boiler is simple in structure and convenient in manufacture, and can effectively avoid the harm that tubes are easy to be exploded due to uneven
heat load distribution of a traditional through-flow boiler.