This comes up quite frequently in retail fireplace shops. To thoroughly answer this question, it helps to understand the basic ways that heat can transfer from one object to another.
Three Types of Heat Transfer
There are three ways heat can transfer from a warmer object to a cooler object . . . through:
A typical forced air furnace will use convective heat to warm your home. A heat exchanger, normally made with steel or stainless steel, is warmed by burning a fuel, either gas, oil, wood or electricity. Once this heat exchanger is hot, a blower fan cycles to blow air through it and distribute the warm air throughout the house via the ductwork.
Radiant heat is how the sun heats. Have you ever been driving down the highway with the sun shining through one side of the car and not the other? The person sitting in the sun feels this radiant energy. The person sitting next to you does not. Another good example is dining outdoors in a restaurant during a cool evening. Radiant heaters from above or portable units keep customers cozy while dining. The heat is delivered directly from a hot object to a cooler object in the room through infrared radiation. Radiant heat, heats objects.
Conduction is probably the most common type of heat transfer and happens when you physically touch a hot object. Have you ever left a metal spoon in a pot of boiling water? It can get very hot. The temperature flow will always go from the hottest to the cooler object. Once the temperature is the same between the two objects, the transfer of heat stops.
How Does This Relate to a Blower Fan on My Fireplace or Stove?
Your fireplace or stove, whether it’s wood or gas, can be operated with or without a fan. Without a fan, you will get the radiant heat from the glass and the front of your fireplace. Without a fan, you will get radiant heat from the front, both sides, the top and even the back of your stove. But by adding a fan to your appliance, you will enjoy convective heat in addition to the radiant heat.
As air from the room moves through convective air chambers designed in the fireplace or stove, heat is transferred from the hot surfaces. The fan then circulates the warm air back into the room. Most fans on fireplaces and stoves use a rheostat to vary the amount of air the fan is moving. Turn the fan up and a higher volume of air is moving through the appliance. By turning the fan down, less air is picking up heat and blowing into the room. Fan adjustments can be done manually, or with many gas fireplaces today, can be done with a multi-function remote control. Fans will increase the heat transfer efficiency of your fireplace or stove.
Most blower fans on fireplaces and stoves will move air in the range of 75 – 250 cubic feet per minute. In the low end of this range, that’s roughly the amount of air a bathroom fan will exhaust. And keeping air moving in your house, even a small amount of air, will help maintain consistent temperatures throughout the house, minimizing cooler or warmer areas of the home.
Fans today are relatively quiet, especially on the lower settings. However, keep in mind whenever a fan is operating by moving air, there will be some noise. A calm day is much quieter than a day with the wind blowing 25 mph. Same with the air moving through your stove or fireplace. Noises from fans other than air moving (squeaks, squeals or hums) indicate a scenario that a dealer would likely want to get involved with. A problematic fan can normally be easily replaced.
Blower fans will not operate, of course, in the event of a power outage but you will still get the benefit of radiant heat. If reliability of power is a concern to you, or if you are off the grid, there are specific models of fireplaces and stoves designed to be strictly radiant heaters.
So, the question comes up again: Do I need a blower fan on my fireplace or stove? It’s all about comfort, based on your circumstances. But most dealers are big fans of fans!