Fired Heaters

Hello Dr. Lieberman. I am Pabu from India. We blew steam up our stack to get more draft. Does this not waste steam? Our heater is small and our stack is short. The structure may not support a taller stack, which is costly. Be kind and advise us.

--Pabu, India


Pabu. My cost effective method to develop more draft is certainly not to use steam. That produces more draft because the molecular weight of steam is 18, and the molecular weight of flue is 30. Best approach is to locate tramp air leaks in the convective box and ducts. Seal them with aluminum duct tape. Eliminating cool air will increase the temperature of the stack, reduce the flue gas density, and thus increase the draft. I have increased draft by as much as 0.1” H₂O by sealing off such leaks. This also may increase heat recovery in the convective section and save energy.

--Regards, Norm