What is the advantage of indirect oil-fired heaters in enclosed areas?

What is the advantage of indirect oil-fired heaters in enclosed areas?

Indirect oil-fired heaters use a heat exchanger to separate combustion gases from the airflow, delivering clean, dry warm air. This makes them safe for use in enclosed or poorly ventilated spaces such as marquees, workshops, or storage facilities. They are highly efficient and can be ducted for even heat distribution.