What equipment is installed to prevent moisture from entering the uptakes and boiler firesides?

The correct answer is stack covers, which are specifically designed to prevent moisture from entering the uptakes and boiler firesides. Stack covers serve as protective barriers that go over the stack or chimney of a boiler system. By covering these components, stack covers help to keep rain, snow, and other forms of moisture from infiltrating the system, which could cause significant issues such as corrosion, reduced efficiency, and operational problems in the boiler.

Moisture can lead to various complications, including the potential for water to mix with fuel or other combustion materials, which can hinder combustion efficiency and increase the risk of equipment damage. Furthermore, excess moisture can create an environment conducive to rust and other forms of deterioration within the boiler system.

In contrast, the other options do not directly serve this purpose. Ventilation fans are primarily used to circulate air and may help in general airflow but do not prevent moisture from entering. Heat exchangers are designed for transferring heat between fluids and do not offer moisture protection. Graduated tubes are typically found in various applications for measuring liquid levels or flow rates but do not relate to moisture prevention in boiler systems.