The chimney was blocked after heavy snow and power failure.

The chimney is blocked after the power failure due to heavy snow for the following reasons:

1. Chimney blockage: Heavy snow will cause the chimney to be blocked, the chimney mouth will be covered with snow, and the flue will also be blocked by snow or ice, resulting in the smoke can not be discharged.

2. Chimney collapse: Heavy snow will lead to chimney collapse. Too much snow will increase the load on the chimney, which will be overwhelmed and collapse.

3. Chimney icing: Heavy snow will cause the chimney to freeze, and the water vapor in the flue gas will form ice after cooling in the chimney, leading to chimney blockage.