What is cowl in firetube boiler?

In a firetube boiler, a cowl refers to a type of vent or chimney cap designed to improve the efficiency of exhaust gas flow. It helps to direct the flue gases upwards and enhances the draft, which can improve combustion efficiency and reduce the likelihood of backdrafts. Properly designed cowls can also help prevent rain and debris from entering the flue system, ensuring safer operation.