I got into an argument with someone who thinks that blowing air across a fireplace will make the room heat more slowly, but based upon the principles computer heat sinks use to get heat away the room would get warmer quicker because you're getting the heat away from the area faster. Which way is true for heating up the room with the fireplace in it along with the rest of the house?
It all depends on the fireplace. If the fireplace is in the center of the room, and you blow on the back side of it, you will increase convection currents , and yes, heat will be distributed faster. If you blow across the front of the fireplace, or you have a fireplace in the wall, you will be increasing the rate by which the air goes up the chimney, and thus most probably it will take more time to heat the room because half of the warm air circulates in the room and half goes up the chimney, in excess of the usual loss of heat in fireplaces. Fireplaces are very inefficient in heating, most of the heat goes to the wall and up the chimney.
There are special fans that can be installed in a fireplace that blow air towards the room, not allowing so much of the heat to go up the chimney and to the walls. So the answer depends on the geometry of how the fan is used.