Heating unit with a high emissivity, porous ceramic flame holder

A heating unit, comprising:

• (a) a flame holder having a plurality of randomly distributed pores, wherein the flame holder comprises at least about 50 wt % ceramic particles that have an emissivity of at least about 0.7 bonded together with a ceramic bonding phase selected from the group consisting of mullite, cordierite, lithium aluminosilicate, titanium silicates, borosilicates, yttrium aluminosilicates, barium osumilite, lithium aluminosilicate glass, magnesium aluminosilicate glass, aluminosilicate glass, titanium silicate glass, borosilicate glass, yttrium aluminosilicate glass, and mixtures thereof,
• (b) means for conveying a fuel/air mixture to the flame holder,
• (c) means for igniting the fuel/air mixture so it forms a flame in proximity to the flame holder,
• (d) means for transferring heat from the flame to a heat transfer medium, and
• (e) means for exhausting combustion products from the heating unit.