We can find direct gas and direct fuel heaters.
Direct fired heater carbon monoxide.
As a result carbon monoxide and hydrogen go to atmosphere or worse mix with tramp air outside the combustion chamber and burn where it is not desirable.
In addition since the air is emissions free operators can use duct systems to transfer warm air from an indirect fired unit to other nearby spaces.
These fumes are generated from a variety of sources including direct fired open flame salamander type heaters and other equipment operating within the building envelope.
A direct fired heating system is typically a device that uses the lower heating value of the fuel to heat the air photos 1 and 2 examples of horizontal rooftop and vertical ground mounted direct fired units.
Figures 1 and 2 show diagrams of non recirculating direct gas fired ahus and figure 3 illustrates a recirculating direct gas.
The products of combustion carbon dioxide co 2 carbon monoxide co nitrogen dioxide no 2 aliphatic aldehydes and water vapor are discharged into the makeup air stream and supplied to the building or process.
Combustion by products depending on a building s intended use direct fired.
Direct fired heaters applications.
Table 1 upper limits for combustion gas emissions from direct fired units and result ing space concentrations 2 3 4.
A direct fired heater works similary to an oven.
On the contrary indirect heaters provide 100 dry and clean air and can operate in closed spaces.
The heat is transferred directly to the product in process.
Direct fired heaters are both more efficient and less expensive than indirect fired heaters.
In addition to the combustion adding humidity and carbon monoxide to the environment.
Carbon monoxide poisoning occurs from exposure to these gases in enclosed spaces creating extreme hazards for all tradespeople.
However there are some cases where an indirect fired heater is the better choice.
Direct fired heaters are both more efficient and less expensive than indirect fired heaters.
Generally direct fired heaters are used on construction sites outdoor applications or warehouses.
Indirect fired heaters do not produce carbon monoxide carbon dioxide or nitrogen dioxide so they are safe to use in tight spaces although they still need an exhaust outlet.
However there are some cases where an indirect fired heater is the better choice.
Proper ventilation is required to avoid buildup of gases such as carbon monoxide.
Having a thorough understanding of all of the differences between these two heater types will ensure you choose the optimal solution for each project.
In either case fuel is wasted and emissions increase.
