What is installed to keep moisture out of the uptakes and boiler firesides?

The correct answer is that stack covers are installed to keep moisture out of the uptakes and boiler firesides. Stack covers serve as protective barriers over the flue gas exhausts, helping to prevent rainwater or moisture from entering the system when the boiler is not in operation. This is crucial because the presence of moisture can lead to serious issues such as corrosion, reduced efficiency, and potential damage to the boiler and connected piping.

In contrast, steam traps are devices used to remove condensate and air from steam systems but do not specifically address moisture ingress from external sources. Heat exchangers function to transfer heat between fluids but are not designed to protect against moisture intrusion. Insulation blankets are used primarily to retain heat and improve thermal efficiency, but they do not prevent moisture from entering the uptakes and boiler firesides. Thus, stack covers are the appropriate solution for this specific issue.