By using of the hot exhaust gases for preheating the combustion air, the fuel consuption is rediced by appox. 30% as compared to conventional gas burners.
As the exhaust gas tempearture is reduced, the exhaust gases can be directly passed into a flue.
You can calculate the point when the additionals price is amortised in your company compared to the conventionally heated furnace with the following calculator.
This calculation is made for a gas-heated tiltable crucible furnace with a capacity of 1100kg aluminum .
Amortization calculations for other furnaces are available of course.