The case of strong radiating influence of low-temperature surfaces of a power aggregate on the process of ignition of air-coal-dust mixture is considered. The experimental researches have carried out on model installation (the fire stand of ASU) with a scale 1:8. In quality of full-scale an aggregate was taken boiler unit КВ-ТК-100-150 Ulyanovsk heat electropower station -2 (station number five) production of a Barnaul boiler factory.

Is shown, that the stability of a coal-dust torch essentially depends on temperature of secondary air and raises from it by increase, the above temperature of air, the above temperature of a torch and the below can be temperature of a radiating surface. With increase of a scale of installation the effect of stability of a torch with rise of temperature of secondary air increases.