Stelter & Brinck
Since 1956
Direct Fired Vs Indirect Fired
Technical Differences

Stelter & Brinck
Since 1956
Direct Fired
• When the burner is fired directly into the process air
stream, this is what we call “Direct Fired”.
• Direct Fired is utilized when the end product will not
be affected by the by-products of combustion.
Indirect Air Heater

Stelter & Brinck
Since 1956
Direct Fired
• Direct fired are less expensive and more efficient than
indirect fired units.
• Direct Firing converts nearly 100% of the combustion
gases used to hot air.
Indirect Air Heater

Stelter & Brinck
Since 1956
Direct Fired Air Heater Diagram
Indirect Air Heater

Stelter & Brinck
Since 1956
Indirect Fired
Indirect Air Heater
• When the burner is fired into a heat exchanger, the air
is being heated indirectly.
• The by-products of combustion are left in the heat
exchanger during this process.

Stelter & Brinck
Since 1956
Indirect Fired Air Heater Diagram
Indirect Air Heater

Stelter & Brinck
Since 1956
Indirect Air Heater Check out this
infographic, for a visual
overview and some
direct vs indirect fired
air heater
applications!!

Stelter & Brinck
Since 1956
Thank you!
Website: www.stelterbrinck.com
Twitter: @stelterbrinck
Phone: 1-513-367-9300
Check out S&B’s Blog Post:
http://www.stelterbrinck.com/blog/direct-fired-vs-indirect-fired/