Open hearth fireplaces, while offering a traditional aesthetic, are notoriously inefficient. Let's break down their efficiency and compare it to other options.

Efficiency of Open Hearth Fireplaces

Several factors contribute to the inefficiency of open-hearth fireplaces:

Factors Affecting Efficiency

Open hearth fireplaces are known for their low efficiency. The primary reason for this is the open design, which allows a significant amount of heat to escape directly up the chimney. The efficiency of an open-hearth fireplace is typically quite low, with ratings ranging from 5-15% [1] [2] [6]. This means that a large portion of the heat generated by the fire is lost, making them a less effective heating source. The United States EPA even advises against using open-hearth fireplaces as a primary heating source [1].

While open-hearth fireplaces are inherently inefficient, there are ways to improve their performance:

Improving Efficiency

• Heat Loss: A significant amount of heat escapes through the chimney [2]. It's estimated that up to 90% of the heat produced can be lost this way [2].
• Drafts and Air Infiltration: Open fireplaces draw in air from the room to fuel the fire, creating drafts and increasing heat loss [2].
• Fuel Consumption: Open fireplaces require larger amounts of wood to sustain a fire and produce heat, which can be costly and environmentally impactful [2].

Comparison to Other Fireplace Types

• Glass Doors: Installing glass doors can reduce heat loss by limiting the amount of room air that escapes up the chimney [6]. However, even with doors, radiant heat can be reduced by half [6].
• Heat Exchangers: Some fireplaces include built-in heat exchangers to capture some of the heat [6].
• Fireplace Inserts: Fireplace inserts are metal boxes with glass doors that fit inside the firebox and use a heat exchange chamber to absorb heat [6]. Inserts can put out up to five times as much heat as an open fireplace [6].

Compared to other fireplace types, open-hearth fireplaces fall short in terms of efficiency. High-efficiency wood burner fireplaces can have efficiency ratings of 70% or more [1]. Enclosed fireplace inserts can also significantly improve efficiency [2]. Pellet stoves and EPA-certified wood stoves are also designed for higher efficiency [2] [5].