Heat output depends on the design of your fire…
There are three main firebox styles — across the range of available brands and designs of outdoor fireplaces — each generating different heat profiles.
1. Steel Firebox
2. Block, Brick or Stone Firebox
3. Masonry (Concrete) Firebox – as used by Flare Fires
Steel fireboxes are common, as mentioned in our post on Flare vs Custom Outdoor Fires, steel fireboxes are often used in custom built fires, and certain brands only provide steel firebox options. There is nothing wrong with steel fireboxes, they get the job done. Flare’s Martello Outdoor Fireplace is our only fire with a steel firebox. Steel can act as a good reflective shield meaning that most steel fireboxes will heat the surrounding outdoor area quickly. However, because of its low thermal mass, compared to stone or concrete, the heat will dissipate quickly, meaning as the wood in the fire burns down, the fire will quickly lose its warmth. A lot of outdoor fireplaces using a steel firebox don’t have any firebricks which add extra heat reflection and thermal mass.
Heat Output: Excellent
Problems to be aware of: Include use of a steel firebox in an outdoor space that will get damp or wet — promoting rust, and the length of the manufacturers warranty.
Block, Brick or Stone Firebox
Many custom build outdoor fireplaces can have no steel firebox, and instead of using refractory firebricks they instead rely on the block or brick which the fire is built with. This can create a good thermal mass that will eventually warm up and then heat the surrounding area, but this will take time. We recommend the use of refractory bricks in the firebox of a custom built fire, to ensure it generates enough heat.
Heat Output: Good to poor
Problems to be aware of: Fires built without a refractory firebrick, and the quality of the materials used to build the fire.
Masonry (Concrete) Firebox
A masonry (concrete) outdoor fireplace has great thermal mass, combined with the use of a high quality refractory firebrick in the firebox area, and you get the best of both worlds — instant heat, and stored heat. You also lose the restrictions of a steel firebox enabling all sorts of cooking options to be added to your fire. The other benefit over a steel or brick or stone fire — at least in Flare’s case, is they come with a Lifetime Limited Warranty.
Heat Output: Excellent
Problems to be aware of: Perhaps the only problem to consider is the masonry can get some hairline cracking from the heat. These hairline cracks open and close with the heat and don’t affect the performance or lifetime of the fire.