Some regions in the USA have recently experienced prolonged freezing conditions with ice due to changes in weather and climate change . This caused widespread power outages in Texas ERCOT and PA/NY. NERC now requires many sites to have a cold weather operation plan to ensure they can stay online when needed in such weather. Blow in doors (or Inlet Heating) can satisfy part of that requirement regarding the inlet filter house.

Adding ‘blow in’ or ‘bypass’ doors, allows some partial combustion air to keep flowing to the turbine compressor even if the filters are completely clogged with snow or ice. Doors are passive devices, that open only when the pressure down stream of the filters reaches a low set point. The weighted doors open automatically. The system allows for operators to respond to the filter freeze-over while allowing the turbine to run briefly until the filters are cleared or replaced.

Doors are hinged and counterweighted with proper weight to just start opening when the negative pressure acts on the door.