| 摘要 |
Various apparatus are disclosed for controlling the combustion air vent of fuel-fired furnaces. For a first embodiment of the invention, a furnace-controlled air valve is placed in the combustion air duct. When the furnace begins a heating cycle, the valve is opened. When the heating cycle ends, the valve is closed and remains closed until the beginning of the next heating cycle. For a second embodiment of the invention, a positive-displacement air pump is placed in the combustion air duct. The air pump pumps air from the exterior into the mechanical room at a controlled rate during each heating cycle of the furnace. The air valve or the air pump is controlled directly or indirectly by the furnace thermostat.
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